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From a769e6c48a4c615cc6a2935b4babd4e6021bf2ab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <ppisar@redhat.com>
Date: Tue, 27 Jun 2023 11:29:42 +0200
Subject: [PATCH] Rebase COLAMD to 3.0.4
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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This version comes with a different, BSD-3-clause, license. The new
license seems to be more liberal because it does not require
propagating it in a documentation of lp_solve.

Copied from COLAMD directory at
<https://github.com/DrTimothyAldenDavis/SuiteSparse.git>.

Petr Písař <ppisar@redhat.com>: Addapted to repackaged sources without
colamd/colamd.{c,h} files.

Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 colamd/License.txt          |   30 +
 colamd/SuiteSparse_config.h |    8 +
 colamd/colamd.c             | 3582 +++++++++++++++++++++++++++++++++++
 colamd/colamd.h             |  236 +++
 4 files changed, 3856 insertions(+)
 create mode 100644 colamd/License.txt
 create mode 100644 colamd/SuiteSparse_config.h
 create mode 100644 colamd/colamd.c
 create mode 100644 colamd/colamd.h

diff --git a/colamd/License.txt b/colamd/License.txt
new file mode 100644
index 0000000..6abd8a4
--- /dev/null
+++ b/colamd/License.txt
@@ -0,0 +1,30 @@
+COLAMD, Copyright 1998-2022, Timothy A. Davis.  http://www.suitesparse.com
+http://www.suitesparse.com
+
+--------------------------------------------------------------------------------
+
+COLAMD License: BSD 3-clause
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions are met:
+        * Redistributions of source code must retain the above copyright
+          notice, this list of conditions and the following disclaimer.
+        * Redistributions in binary form must reproduce the above copyright
+          notice, this list of conditions and the following disclaimer in the
+          documentation and/or other materials provided with the distribution.
+        * Neither the name of the organizations to which the authors are
+          affiliated, nor the names of its contributors may be used to endorse
+          or promote products derived from this software without specific prior
+          written permission.
+
+    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+    AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+    ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+    DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+    (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+    SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+    OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+    DAMAGE.
diff --git a/colamd/SuiteSparse_config.h b/colamd/SuiteSparse_config.h
new file mode 100644
index 0000000..9516457
--- /dev/null
+++ b/colamd/SuiteSparse_config.h
@@ -0,0 +1,8 @@
+/* The following includes should be in colamd.h, but upstream places them to
+ * separate SuiteSparse_config.h. */
+#include <limits.h> /* for INT_MAX */
+#include <math.h>   /* for sqrt() */
+#include <stddef.h> /* for size_t */
+#include <stdint.h> /* for int32_t, int64_t */
+#include <stdio.h>  /* for printf() */
+#define SUITESPARSE_PRINTF(args) { (void)printf args; }
diff --git a/colamd/colamd.c b/colamd/colamd.c
new file mode 100644
index 0000000..af5b27f
--- /dev/null
+++ b/colamd/colamd.c
@@ -0,0 +1,3582 @@
+//------------------------------------------------------------------------------
+// COLAMD/Source/colamd.c: column approximate minimum degree ordering
+//------------------------------------------------------------------------------
+
+// COLAMD, Copyright (c) 1998-2022, Timothy A. Davis and Stefan Larimore,
+// All Rights Reserved.
+// SPDX-License-Identifier: BSD-3-clause
+
+//------------------------------------------------------------------------------
+
+/* COLAMD / SYMAMD
+
+    colamd:  an approximate minimum degree column ordering algorithm,
+    	for LU factorization of symmetric or unsymmetric matrices,
+	QR factorization, least squares, interior point methods for
+	linear programming problems, and other related problems.
+
+    symamd:  an approximate minimum degree ordering algorithm for Cholesky
+    	factorization of symmetric matrices.
+
+    Purpose:
+
+	Colamd computes a permutation Q such that the Cholesky factorization of
+	(AQ)'(AQ) has less fill-in and requires fewer floating point operations
+	than A'A.  This also provides a good ordering for sparse partial
+	pivoting methods, P(AQ) = LU, where Q is computed prior to numerical
+	factorization, and P is computed during numerical factorization via
+	conventional partial pivoting with row interchanges.  Colamd is the
+	column ordering method used in SuperLU, part of the ScaLAPACK library.
+	It is also available as built-in function in MATLAB Version 6,
+	available from MathWorks, Inc. (http://www.mathworks.com).  This
+	routine can be used in place of colmmd in MATLAB.
+
+    	Symamd computes a permutation P of a symmetric matrix A such that the
+	Cholesky factorization of PAP' has less fill-in and requires fewer
+	floating point operations than A.  Symamd constructs a matrix M such
+	that M'M has the same nonzero pattern of A, and then orders the columns
+	of M using colmmd.  The column ordering of M is then returned as the
+	row and column ordering P of A. 
+
+    Authors:
+
+	The authors of the code itself are Stefan I. Larimore and Timothy A.
+	Davis (DrTimothyAldenDavis@gmail.com).  The algorithm was
+	developed in collaboration with John Gilbert, Xerox PARC, and Esmond
+	Ng, Oak Ridge National Laboratory.
+
+    Acknowledgements:
+
+	This work was supported by the National Science Foundation, under
+	grants DMS-9504974 and DMS-9803599.
+
+    Copyright and License:
+
+	Copyright (c) 1998-2022, Timothy A. Davis, All Rights Reserved.
+	COLAMD is also available under alternate licenses, contact T. Davis
+	for details.
+
+        See COLAMD/Doc/License.txt for the license.
+
+    Availability:
+
+	The colamd/symamd library is available at http://www.suitesparse.com
+	Appears as ACM Algorithm 836.
+
+    See the ChangeLog file for changes since Version 1.0.
+
+    References:
+
+	T. A. Davis, J. R. Gilbert, S. Larimore, E. Ng, An approximate column
+	minimum degree ordering algorithm, ACM Transactions on Mathematical
+	Software, vol. 30, no. 3., pp. 353-376, 2004.
+
+	T. A. Davis, J. R. Gilbert, S. Larimore, E. Ng, Algorithm 836: COLAMD,
+	an approximate column minimum degree ordering algorithm, ACM
+	Transactions on Mathematical Software, vol. 30, no. 3., pp. 377-380,
+	2004.
+
+*/
+
+/* ========================================================================== */
+/* === Description of user-callable routines ================================ */
+/* ========================================================================== */
+
+/* COLAMD includes both int32_t and int64_t versions of all its routines.
+    The description below is for the int32_t version.  For int64_t, all
+    int32_t arguments become int64_t.
+
+    ----------------------------------------------------------------------------
+    colamd_recommended:
+    ----------------------------------------------------------------------------
+
+	C syntax:
+
+	    #include "colamd.h"
+	    size_t colamd_recommended (int32_t nnz, int32_t n_row, int32_t n_col) ;
+	    size_t colamd_l_recommended (int64_t nnz,
+                int64_t n_row, int64_t n_col) ;
+
+	Purpose:
+
+	    Returns recommended value of Alen for use by colamd.  Returns 0
+	    if any input argument is negative.  The use of this routine
+	    is optional.  Not needed for symamd, which dynamically allocates
+	    its own memory.
+
+	Arguments (all input arguments):
+
+	    int32_t nnz ;	Number of nonzeros in the matrix A.  This must
+				be the same value as p [n_col] in the call to
+				colamd - otherwise you will get a wrong value
+				of the recommended memory to use.
+
+	    int32_t n_row ;	Number of rows in the matrix A.
+
+	    int32_t n_col ;	Number of columns in the matrix A.
+
+    ----------------------------------------------------------------------------
+    colamd_set_defaults:
+    ----------------------------------------------------------------------------
+
+	C syntax:
+
+	    #include "colamd.h"
+	    colamd_set_defaults (double knobs [COLAMD_KNOBS]) ;
+	    colamd_l_set_defaults (double knobs [COLAMD_KNOBS]) ;
+
+	Purpose:
+
+	    Sets the default parameters.  The use of this routine is optional.
+
+	Arguments:
+
+	    double knobs [COLAMD_KNOBS] ;	Output only.
+
+		NOTE: the meaning of the dense row/col knobs has changed in v2.4
+
+		knobs [0] and knobs [1] control dense row and col detection:
+
+		Colamd: rows with more than
+		max (16, knobs [COLAMD_DENSE_ROW] * sqrt (n_col))
+		entries are removed prior to ordering.  Columns with more than
+		max (16, knobs [COLAMD_DENSE_COL] * sqrt (MIN (n_row,n_col)))
+		entries are removed prior to
+		ordering, and placed last in the output column ordering. 
+
+		Symamd: uses only knobs [COLAMD_DENSE_ROW], which is knobs [0].
+		Rows and columns with more than
+		max (16, knobs [COLAMD_DENSE_ROW] * sqrt (n))
+		entries are removed prior to ordering, and placed last in the
+		output ordering.
+
+		COLAMD_DENSE_ROW and COLAMD_DENSE_COL are defined as 0 and 1,
+		respectively, in colamd.h.  Default values of these two knobs
+		are both 10.  Currently, only knobs [0] and knobs [1] are
+		used, but future versions may use more knobs.  If so, they will
+		be properly set to their defaults by the future version of
+		colamd_set_defaults, so that the code that calls colamd will
+		not need to change, assuming that you either use
+		colamd_set_defaults, or pass a (double *) NULL pointer as the
+		knobs array to colamd or symamd.
+
+	    knobs [2]: aggressive absorption
+
+	        knobs [COLAMD_AGGRESSIVE] controls whether or not to do
+	        aggressive absorption during the ordering.  Default is TRUE.
+
+
+    ----------------------------------------------------------------------------
+    colamd:
+    ----------------------------------------------------------------------------
+
+	C syntax:
+
+	    #include "colamd.h"
+	    int colamd (int32_t n_row, int32_t n_col, int32_t Alen, int32_t *A, int32_t *p,
+	    	double knobs [COLAMD_KNOBS], int32_t stats [COLAMD_STATS]) ;
+	    int colamd_l (int64_t n_row,
+                int64_t n_col, int64_t Alen,
+                int64_t *A, int64_t *p, double knobs
+                [COLAMD_KNOBS], int64_t stats [COLAMD_STATS]) ;
+
+	Purpose:
+
+	    Computes a column ordering (Q) of A such that P(AQ)=LU or
+	    (AQ)'AQ=LL' have less fill-in and require fewer floating point
+	    operations than factorizing the unpermuted matrix A or A'A,
+	    respectively.
+	    
+	Returns:
+
+	    TRUE (1) if successful, FALSE (0) otherwise.
+
+	Arguments:
+
+	    int32_t n_row ;		Input argument.
+
+		Number of rows in the matrix A.
+		Restriction:  n_row >= 0.
+		Colamd returns FALSE if n_row is negative.
+
+	    int32_t n_col ;		Input argument.
+
+		Number of columns in the matrix A.
+		Restriction:  n_col >= 0.
+		Colamd returns FALSE if n_col is negative.
+
+	    int32_t Alen ;		Input argument.
+
+		Restriction (see note):
+		Alen >= 2*nnz + 6*(n_col+1) + 4*(n_row+1) + n_col
+		Colamd returns FALSE if these conditions are not met.
+
+		Note:  this restriction makes an modest assumption regarding
+		the size of the two typedef's structures in colamd.h.
+		We do, however, guarantee that
+
+			Alen >= colamd_recommended (nnz, n_row, n_col)
+
+		will be sufficient.  Note: the macro version does not check
+		for integer overflow, and thus is not recommended.  Use
+		the colamd_recommended routine instead.
+
+	    int32_t A [Alen] ;	Input argument, undefined on output.
+
+		A is an integer array of size Alen.  Alen must be at least as
+		large as the bare minimum value given above, but this is very
+		low, and can result in excessive run time.  For best
+		performance, we recommend that Alen be greater than or equal to
+		colamd_recommended (nnz, n_row, n_col), which adds
+		nnz/5 to the bare minimum value given above.
+
+		On input, the row indices of the entries in column c of the
+		matrix are held in A [(p [c]) ... (p [c+1]-1)].  The row indices
+		in a given column c need not be in ascending order, and
+		duplicate row indices may be be present.  However, colamd will
+		work a little faster if both of these conditions are met
+		(Colamd puts the matrix into this format, if it finds that the
+		the conditions are not met).
+
+		The matrix is 0-based.  That is, rows are in the range 0 to
+		n_row-1, and columns are in the range 0 to n_col-1.  Colamd
+		returns FALSE if any row index is out of range.
+
+		The contents of A are modified during ordering, and are
+		undefined on output.
+
+	    int32_t p [n_col+1] ;	Both input and output argument.
+
+		p is an integer array of size n_col+1.  On input, it holds the
+		"pointers" for the column form of the matrix A.  Column c of
+		the matrix A is held in A [(p [c]) ... (p [c+1]-1)].  The first
+		entry, p [0], must be zero, and p [c] <= p [c+1] must hold
+		for all c in the range 0 to n_col-1.  The value p [n_col] is
+		thus the total number of entries in the pattern of the matrix A.
+		Colamd returns FALSE if these conditions are not met.
+
+		On output, if colamd returns TRUE, the array p holds the column
+		permutation (Q, for P(AQ)=LU or (AQ)'(AQ)=LL'), where p [0] is
+		the first column index in the new ordering, and p [n_col-1] is
+		the last.  That is, p [k] = j means that column j of A is the
+		kth pivot column, in AQ, where k is in the range 0 to n_col-1
+		(p [0] = j means that column j of A is the first column in AQ).
+
+		If colamd returns FALSE, then no permutation is returned, and
+		p is undefined on output.
+
+	    double knobs [COLAMD_KNOBS] ;	Input argument.
+
+		See colamd_set_defaults for a description.
+
+	    int32_t stats [COLAMD_STATS] ;		Output argument.
+
+		Statistics on the ordering, and error status.
+		See colamd.h for related definitions.
+		Colamd returns FALSE if stats is not present.
+
+		stats [0]:  number of dense or empty rows ignored.
+
+		stats [1]:  number of dense or empty columns ignored (and
+				ordered last in the output permutation p)
+				Note that a row can become "empty" if it
+				contains only "dense" and/or "empty" columns,
+				and similarly a column can become "empty" if it
+				only contains "dense" and/or "empty" rows.
+
+		stats [2]:  number of garbage collections performed.
+				This can be excessively high if Alen is close
+				to the minimum required value.
+
+		stats [3]:  status code.  < 0 is an error code.
+			    > 1 is a warning or notice.
+
+			0	OK.  Each column of the input matrix contained
+				row indices in increasing order, with no
+				duplicates.
+
+			1	OK, but columns of input matrix were jumbled
+				(unsorted columns or duplicate entries).  Colamd
+				had to do some extra work to sort the matrix
+				first and remove duplicate entries, but it
+				still was able to return a valid permutation
+				(return value of colamd was TRUE).
+
+					stats [4]: highest numbered column that
+						is unsorted or has duplicate
+						entries.
+					stats [5]: last seen duplicate or
+						unsorted row index.
+					stats [6]: number of duplicate or
+						unsorted row indices.
+
+			-1	A is a null pointer
+
+			-2	p is a null pointer
+
+			-3 	n_row is negative
+
+					stats [4]: n_row
+
+			-4	n_col is negative
+
+					stats [4]: n_col
+
+			-5	number of nonzeros in matrix is negative
+
+					stats [4]: number of nonzeros, p [n_col]
+
+			-6	p [0] is nonzero
+
+					stats [4]: p [0]
+
+			-7	A is too small
+
+					stats [4]: required size
+					stats [5]: actual size (Alen)
+
+			-8	a column has a negative number of entries
+
+					stats [4]: column with < 0 entries
+					stats [5]: number of entries in col
+
+			-9	a row index is out of bounds
+
+					stats [4]: column with bad row index
+					stats [5]: bad row index
+					stats [6]: n_row, # of rows of matrx
+
+			-10	(unused; see symamd.c)
+
+			-999	(unused; see symamd.c)
+
+		Future versions may return more statistics in the stats array.
+
+	Example:
+	
+	    See colamd_example.c for a complete example.
+
+	    To order the columns of a 5-by-4 matrix with 11 nonzero entries in
+	    the following nonzero pattern
+
+	    	x 0 x 0
+		x 0 x x
+		0 x x 0
+		0 0 x x
+		x x 0 0
+
+	    with default knobs and no output statistics, do the following:
+
+		#include "colamd.h"
+		#define ALEN 100
+		int32_t A [ALEN] = {0, 1, 4, 2, 4, 0, 1, 2, 3, 1, 3} ;
+		int32_t p [ ] = {0, 3, 5, 9, 11} ;
+		int32_t stats [COLAMD_STATS] ;
+		colamd (5, 4, ALEN, A, p, (double *) NULL, stats) ;
+
+	    The permutation is returned in the array p, and A is destroyed.
+
+    ----------------------------------------------------------------------------
+    symamd:
+    ----------------------------------------------------------------------------
+
+	C syntax:
+
+	    #include "colamd.h"
+	    int symamd (int32_t n, int32_t *A, int32_t *p, int32_t *perm,
+	    	double knobs [COLAMD_KNOBS], int32_t stats [COLAMD_STATS],
+		void (*allocate) (size_t, size_t), void (*release) (void *)) ;
+	    int symamd_l (int64_t n, int64_t *A,
+                int64_t *p, int64_t *perm, double knobs
+                [COLAMD_KNOBS], int64_t stats [COLAMD_STATS], void
+                (*allocate) (size_t, size_t), void (*release) (void *)) ;
+
+	Purpose:
+
+    	    The symamd routine computes an ordering P of a symmetric sparse
+	    matrix A such that the Cholesky factorization PAP' = LL' remains
+	    sparse.  It is based on a column ordering of a matrix M constructed
+	    so that the nonzero pattern of M'M is the same as A.  The matrix A
+	    is assumed to be symmetric; only the strictly lower triangular part
+	    is accessed.  You must pass your selected memory allocator (usually
+	    calloc/free or mxCalloc/mxFree) to symamd, for it to allocate
+	    memory for the temporary matrix M.
+
+	Returns:
+
+	    TRUE (1) if successful, FALSE (0) otherwise.
+
+	Arguments:
+
+	    int32_t n ;		Input argument.
+
+	    	Number of rows and columns in the symmetrix matrix A.
+		Restriction:  n >= 0.
+		Symamd returns FALSE if n is negative.
+
+	    int32_t A [nnz] ;	Input argument.
+
+	    	A is an integer array of size nnz, where nnz = p [n].
+		
+		The row indices of the entries in column c of the matrix are
+		held in A [(p [c]) ... (p [c+1]-1)].  The row indices in a
+		given column c need not be in ascending order, and duplicate
+		row indices may be present.  However, symamd will run faster
+		if the columns are in sorted order with no duplicate entries. 
+
+		The matrix is 0-based.  That is, rows are in the range 0 to
+		n-1, and columns are in the range 0 to n-1.  Symamd
+		returns FALSE if any row index is out of range.
+
+		The contents of A are not modified.
+
+	    int32_t p [n+1] ;   	Input argument.
+
+		p is an integer array of size n+1.  On input, it holds the
+		"pointers" for the column form of the matrix A.  Column c of
+		the matrix A is held in A [(p [c]) ... (p [c+1]-1)].  The first
+		entry, p [0], must be zero, and p [c] <= p [c+1] must hold
+		for all c in the range 0 to n-1.  The value p [n] is
+		thus the total number of entries in the pattern of the matrix A.
+		Symamd returns FALSE if these conditions are not met.
+
+		The contents of p are not modified.
+
+	    int32_t perm [n+1] ;   	Output argument.
+
+		On output, if symamd returns TRUE, the array perm holds the
+		permutation P, where perm [0] is the first index in the new
+		ordering, and perm [n-1] is the last.  That is, perm [k] = j
+		means that row and column j of A is the kth column in PAP',
+		where k is in the range 0 to n-1 (perm [0] = j means
+		that row and column j of A are the first row and column in
+		PAP').  The array is used as a workspace during the ordering,
+		which is why it must be of length n+1, not just n.
+
+	    double knobs [COLAMD_KNOBS] ;	Input argument.
+
+		See colamd_set_defaults for a description.
+
+	    int32_t stats [COLAMD_STATS] ;		Output argument.
+
+		Statistics on the ordering, and error status.
+		See colamd.h for related definitions.
+		Symamd returns FALSE if stats is not present.
+
+		stats [0]:  number of dense or empty row and columns ignored
+				(and ordered last in the output permutation 
+				perm).  Note that a row/column can become
+				"empty" if it contains only "dense" and/or
+				"empty" columns/rows.
+
+		stats [1]:  (same as stats [0])
+
+		stats [2]:  number of garbage collections performed.
+
+		stats [3]:  status code.  < 0 is an error code.
+			    > 1 is a warning or notice.
+
+			0	OK.  Each column of the input matrix contained
+				row indices in increasing order, with no
+				duplicates.
+
+			1	OK, but columns of input matrix were jumbled
+				(unsorted columns or duplicate entries).  Symamd
+				had to do some extra work to sort the matrix
+				first and remove duplicate entries, but it
+				still was able to return a valid permutation
+				(return value of symamd was TRUE).
+
+					stats [4]: highest numbered column that
+						is unsorted or has duplicate
+						entries.
+					stats [5]: last seen duplicate or
+						unsorted row index.
+					stats [6]: number of duplicate or
+						unsorted row indices.
+
+			-1	A is a null pointer
+
+			-2	p is a null pointer
+
+			-3	(unused, see colamd.c)
+
+			-4 	n is negative
+
+					stats [4]: n
+
+			-5	number of nonzeros in matrix is negative
+
+					stats [4]: # of nonzeros (p [n]).
+
+			-6	p [0] is nonzero
+
+					stats [4]: p [0]
+
+			-7	(unused)
+
+			-8	a column has a negative number of entries
+
+					stats [4]: column with < 0 entries
+					stats [5]: number of entries in col
+
+			-9	a row index is out of bounds
+
+					stats [4]: column with bad row index
+					stats [5]: bad row index
+					stats [6]: n_row, # of rows of matrx
+
+			-10	out of memory (unable to allocate temporary
+				workspace for M or count arrays using the
+				"allocate" routine passed into symamd).
+
+		Future versions may return more statistics in the stats array.
+
+	    void * (*allocate) (size_t, size_t)
+
+	    	A pointer to a function providing memory allocation.  The
+		allocated memory must be returned initialized to zero.  For a
+		C application, this argument should normally be a pointer to
+		calloc.  For a MATLAB mexFunction, the routine mxCalloc is
+		passed instead.
+
+	    void (*release) (size_t, size_t)
+
+	    	A pointer to a function that frees memory allocated by the
+		memory allocation routine above.  For a C application, this
+		argument should normally be a pointer to free.  For a MATLAB
+		mexFunction, the routine mxFree is passed instead.
+
+
+    ----------------------------------------------------------------------------
+    colamd_report:
+    ----------------------------------------------------------------------------
+
+	C syntax:
+
+	    #include "colamd.h"
+	    colamd_report (int32_t stats [COLAMD_STATS]) ;
+	    colamd_l_report (int64_t stats [COLAMD_STATS]) ;
+
+	Purpose:
+
+	    Prints the error status and statistics recorded in the stats
+	    array on the standard error output (for a standard C routine)
+	    or on the MATLAB output (for a mexFunction).
+
+	Arguments:
+
+	    int32_t stats [COLAMD_STATS] ;	Input only.  Statistics from colamd.
+
+
+    ----------------------------------------------------------------------------
+    symamd_report:
+    ----------------------------------------------------------------------------
+
+	C syntax:
+
+	    #include "colamd.h"
+	    symamd_report (int32_t stats [COLAMD_STATS]) ;
+	    symamd_l_report (int64_t stats [COLAMD_STATS]) ;
+
+	Purpose:
+
+	    Prints the error status and statistics recorded in the stats
+	    array on the standard error output (for a standard C routine)
+	    or on the MATLAB output (for a mexFunction).
+
+	Arguments:
+
+	    int32_t stats [COLAMD_STATS] ;	Input only.  Statistics from symamd.
+
+
+*/
+
+/* ========================================================================== */
+/* === Scaffolding code definitions  ======================================== */
+/* ========================================================================== */
+
+/* Ensure that debugging is turned off: */
+#ifndef NDEBUG
+#define NDEBUG
+#endif
+
+/* turn on debugging by uncommenting the following line
+ #undef NDEBUG
+*/
+
+/*
+   Our "scaffolding code" philosophy:  In our opinion, well-written library
+   code should keep its "debugging" code, and just normally have it turned off
+   by the compiler so as not to interfere with performance.  This serves
+   several purposes:
+
+   (1) assertions act as comments to the reader, telling you what the code
+	expects at that point.  All assertions will always be true (unless
+	there really is a bug, of course).
+
+   (2) leaving in the scaffolding code assists anyone who would like to modify
+	the code, or understand the algorithm (by reading the debugging output,
+	one can get a glimpse into what the code is doing).
+
+   (3) (gasp!) for actually finding bugs.  This code has been heavily tested
+	and "should" be fully functional and bug-free ... but you never know...
+
+    The code will become outrageously slow when debugging is
+    enabled.  To control the level of debugging output, set an environment
+    variable D to 0 (little), 1 (some), 2, 3, or 4 (lots).  When debugging,
+    you should see the following message on the standard output:
+
+    	colamd: debug version, D = 1 (THIS WILL BE SLOW!)
+
+    or a similar message for symamd.  If you don't, then debugging has not
+    been enabled.
+
+*/
+
+/* ========================================================================== */
+/* === Include files ======================================================== */
+/* ========================================================================== */
+
+#include "colamd.h"
+
+#ifndef NULL
+#define NULL ((void *) 0)
+#endif
+
+/* ========================================================================== */
+/* === int32_t or int64_t ============================================== */
+/* ========================================================================== */
+
+#ifdef DLONG
+
+#define Int int64_t
+#define UInt uint64_t
+#define ID  "%" PRId64
+#define Int_MAX INT64_MAX
+
+#define COLAMD_recommended colamd_l_recommended
+#define COLAMD_set_defaults colamd_l_set_defaults
+#define COLAMD_MAIN colamd_l
+#define SYMAMD_MAIN symamd_l
+#define COLAMD_report colamd_l_report
+#define SYMAMD_report symamd_l_report
+
+#else
+
+#define Int int32_t
+#define UInt uint32_t
+#define ID "%d"
+#define Int_MAX INT32_MAX
+
+#define COLAMD_recommended colamd_recommended
+#define COLAMD_set_defaults colamd_set_defaults
+#define COLAMD_MAIN colamd
+#define SYMAMD_MAIN symamd
+#define COLAMD_report colamd_report
+#define SYMAMD_report symamd_report
+
+#endif
+
+/* ========================================================================== */
+/* === Row and Column structures ============================================ */
+/* ========================================================================== */
+
+/* User code that makes use of the colamd/symamd routines need not directly */
+/* reference these structures.  They are used only for colamd_recommended. */
+
+typedef struct Colamd_Col_struct
+{
+    Int start ;		/* index for A of first row in this column, or DEAD */
+			/* if column is dead */
+    Int length ;	/* number of rows in this column */
+    union
+    {
+	Int thickness ;	/* number of original columns represented by this */
+			/* col, if the column is alive */
+	Int parent ;	/* parent in parent tree super-column structure, if */
+			/* the column is dead */
+    } shared1 ;
+    union
+    {
+	Int score ;	/* the score used to maintain heap, if col is alive */
+	Int order ;	/* pivot ordering of this column, if col is dead */
+    } shared2 ;
+    union
+    {
+	Int headhash ;	/* head of a hash bucket, if col is at the head of */
+			/* a degree list */
+	Int hash ;	/* hash value, if col is not in a degree list */
+	Int prev ;	/* previous column in degree list, if col is in a */
+			/* degree list (but not at the head of a degree list) */
+    } shared3 ;
+    union
+    {
+	Int degree_next ;	/* next column, if col is in a degree list */
+	Int hash_next ;		/* next column, if col is in a hash list */
+    } shared4 ;
+
+} Colamd_Col ;
+
+typedef struct Colamd_Row_struct
+{
+    Int start ;		/* index for A of first col in this row */
+    Int length ;	/* number of principal columns in this row */
+    union
+    {
+	Int degree ;	/* number of principal & non-principal columns in row */
+	Int p ;		/* used as a row pointer in init_rows_cols () */
+    } shared1 ;
+    union
+    {
+	Int mark ;	/* for computing set differences and marking dead rows*/
+	Int first_column ;/* first column in row (used in garbage collection) */
+    } shared2 ;
+
+} Colamd_Row ;
+
+/* ========================================================================== */
+/* === Definitions ========================================================== */
+/* ========================================================================== */
+
+/* Routines are either user-callable or PRIVATE (not user-callable) */
+#define PRIVATE static 
+
+#define DENSE_DEGREE(alpha,n) \
+    ((Int) MAX (16.0, (alpha) * sqrt ((double) (n))))
+
+#define MAX(a,b) (((a) > (b)) ? (a) : (b))
+#define MIN(a,b) (((a) < (b)) ? (a) : (b))
+
+#define ONES_COMPLEMENT(r) (-(r)-1)
+
+/* -------------------------------------------------------------------------- */
+/* Change for version 2.1:  define TRUE and FALSE only if not yet defined */  
+/* -------------------------------------------------------------------------- */
+
+#ifndef TRUE
+#define TRUE (1)
+#endif
+
+#ifndef FALSE
+#define FALSE (0)
+#endif
+
+/* -------------------------------------------------------------------------- */
+
+#define EMPTY	(-1)
+
+/* Row and column status */
+#define ALIVE	(0)
+#define DEAD	(-1)
+
+/* Column status */
+#define DEAD_PRINCIPAL		(-1)
+#define DEAD_NON_PRINCIPAL	(-2)
+
+/* Macros for row and column status update and checking. */
+#define ROW_IS_DEAD(r)			ROW_IS_MARKED_DEAD (Row[r].shared2.mark)
+#define ROW_IS_MARKED_DEAD(row_mark)	(row_mark < ALIVE)
+#define ROW_IS_ALIVE(r)			(Row [r].shared2.mark >= ALIVE)
+#define COL_IS_DEAD(c)			(Col [c].start < ALIVE)
+#define COL_IS_ALIVE(c)			(Col [c].start >= ALIVE)
+#define COL_IS_DEAD_PRINCIPAL(c)	(Col [c].start == DEAD_PRINCIPAL)
+#define KILL_ROW(r)			{ Row [r].shared2.mark = DEAD ; }
+#define KILL_PRINCIPAL_COL(c)		{ Col [c].start = DEAD_PRINCIPAL ; }
+#define KILL_NON_PRINCIPAL_COL(c)	{ Col [c].start = DEAD_NON_PRINCIPAL ; }
+
+/* ========================================================================== */
+/* === Colamd reporting mechanism =========================================== */
+/* ========================================================================== */
+
+#if defined (MATLAB_MEX_FILE) || defined (MATHWORKS)
+/* In MATLAB, matrices are 1-based to the user, but 0-based internally */
+#define INDEX(i) ((i)+1)
+#else
+/* In C, matrices are 0-based and indices are reported as such in *_report */
+#define INDEX(i) (i)
+#endif
+
+/* ========================================================================== */
+/* === Prototypes of PRIVATE routines ======================================= */
+/* ========================================================================== */
+
+PRIVATE Int init_rows_cols
+(
+    Int n_row,
+    Int n_col,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int A [],
+    Int p [],
+    Int stats [COLAMD_STATS]
+) ;
+
+PRIVATE void init_scoring
+(
+    Int n_row,
+    Int n_col,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int A [],
+    Int head [],
+    double knobs [COLAMD_KNOBS],
+    Int *p_n_row2,
+    Int *p_n_col2,
+    Int *p_max_deg
+) ;
+
+PRIVATE Int find_ordering
+(
+    Int n_row,
+    Int n_col,
+    Int Alen,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int A [],
+    Int head [],
+    Int n_col2,
+    Int max_deg,
+    Int pfree,
+    Int aggressive
+) ;
+
+PRIVATE void order_children
+(
+    Int n_col,
+    Colamd_Col Col [],
+    Int p []
+) ;
+
+PRIVATE void detect_super_cols
+(
+
+#ifndef NDEBUG
+    Int n_col,
+    Colamd_Row Row [],
+#endif /* NDEBUG */
+
+    Colamd_Col Col [],
+    Int A [],
+    Int head [],
+    Int row_start,
+    Int row_length
+) ;
+
+PRIVATE Int garbage_collection
+(
+    Int n_row,
+    Int n_col,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int A [],
+    Int *pfree
+) ;
+
+PRIVATE Int clear_mark
+(
+    Int tag_mark,
+    Int max_mark,
+    Int n_row,
+    Colamd_Row Row []
+) ;
+
+PRIVATE void print_report
+(
+    char *method,
+    Int stats [COLAMD_STATS]
+) ;
+
+/* ========================================================================== */
+/* === Debugging prototypes and definitions ================================= */
+/* ========================================================================== */
+
+#ifndef NDEBUG
+
+#include <assert.h>
+
+/* colamd_debug is the *ONLY* global variable, and is only */
+/* present when debugging */
+
+PRIVATE Int colamd_debug = 0 ;	/* debug print level */
+
+#define DEBUG0(params) { SUITESPARSE_PRINTF (params) ; }
+#define DEBUG1(params) { if (colamd_debug >= 1) SUITESPARSE_PRINTF (params) ; }
+#define DEBUG2(params) { if (colamd_debug >= 2) SUITESPARSE_PRINTF (params) ; }
+#define DEBUG3(params) { if (colamd_debug >= 3) SUITESPARSE_PRINTF (params) ; }
+#define DEBUG4(params) { if (colamd_debug >= 4) SUITESPARSE_PRINTF (params) ; }
+
+#ifdef MATLAB_MEX_FILE
+#define ASSERT(expression) (mxAssert ((expression), ""))
+#else
+#define ASSERT(expression) (assert (expression))
+#endif /* MATLAB_MEX_FILE */
+
+PRIVATE void colamd_get_debug	/* gets the debug print level from getenv */
+(
+    char *method
+) ;
+
+PRIVATE void debug_deg_lists
+(
+    Int n_row,
+    Int n_col,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int head [],
+    Int min_score,
+    Int should,
+    Int max_deg
+) ;
+
+PRIVATE void debug_mark
+(
+    Int n_row,
+    Colamd_Row Row [],
+    Int tag_mark,
+    Int max_mark
+) ;
+
+PRIVATE void debug_matrix
+(
+    Int n_row,
+    Int n_col,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int A []
+) ;
+
+PRIVATE void debug_structures
+(
+    Int n_row,
+    Int n_col,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int A [],
+    Int n_col2
+) ;
+
+#else /* NDEBUG */
+
+/* === No debugging ========================================================= */
+
+#define DEBUG0(params) ;
+#define DEBUG1(params) ;
+#define DEBUG2(params) ;
+#define DEBUG3(params) ;
+#define DEBUG4(params) ;
+
+#define ASSERT(expression)
+
+#endif /* NDEBUG */
+
+/* ========================================================================== */
+/* === USER-CALLABLE ROUTINES: ============================================== */
+/* ========================================================================== */
+
+/* ========================================================================== */
+/* === colamd_recommended =================================================== */
+/* ========================================================================== */
+
+/*
+    The colamd_recommended routine returns the suggested size for Alen.  This
+    value has been determined to provide good balance between the number of
+    garbage collections and the memory requirements for colamd.  If any
+    argument is negative, or if integer overflow occurs, a 0 is returned as an
+    error condition.  2*nnz space is required for the row and column
+    indices of the matrix. COLAMD_C (n_col) + COLAMD_R (n_row) space is
+    required for the Col and Row arrays, respectively, which are internal to
+    colamd (roughly 6*n_col + 4*n_row).  An additional n_col space is the
+    minimal amount of "elbow room", and nnz/5 more space is recommended for
+    run time efficiency.
+
+    Alen is approximately 2.2*nnz + 7*n_col + 4*n_row + 10.
+
+    This function is not needed when using symamd.
+*/
+
+/* add two values of type size_t, and check for integer overflow */
+static size_t t_add (size_t a, size_t b, int *ok)
+{
+    (*ok) = (*ok) && ((a + b) >= MAX (a,b)) ;
+    return ((*ok) ? (a + b) : 0) ;
+}
+
+/* compute a*k where k is a small integer, and check for integer overflow */
+static size_t t_mult (size_t a, size_t k, int *ok)
+{
+    size_t i, s = 0 ;
+    for (i = 0 ; i < k ; i++)
+    {
+	s = t_add (s, a, ok) ;
+    }
+    return (s) ;
+}
+
+/* size of the Col and Row structures */
+#define COLAMD_C(n_col,ok) \
+    ((t_mult (t_add (n_col, 1, ok), sizeof (Colamd_Col), ok) / sizeof (Int)))
+
+#define COLAMD_R(n_row,ok) \
+    ((t_mult (t_add (n_row, 1, ok), sizeof (Colamd_Row), ok) / sizeof (Int)))
+
+
+size_t COLAMD_recommended	/* returns recommended value of Alen. */
+(
+    /* === Parameters ======================================================= */
+
+    Int nnz,			/* number of nonzeros in A */
+    Int n_row,			/* number of rows in A */
+    Int n_col			/* number of columns in A */
+)
+{
+    size_t s, c, r ;
+    int ok = TRUE ;
+    if (nnz < 0 || n_row < 0 || n_col < 0)
+    {
+	return (0) ;
+    }
+    s = t_mult (nnz, 2, &ok) ;	    /* 2*nnz */
+    c = COLAMD_C (n_col, &ok) ;	    /* size of column structures */
+    r = COLAMD_R (n_row, &ok) ;	    /* size of row structures */
+    s = t_add (s, c, &ok) ;
+    s = t_add (s, r, &ok) ;
+    s = t_add (s, n_col, &ok) ;	    /* elbow room */
+    s = t_add (s, nnz/5, &ok) ;	    /* elbow room */
+    return (ok ? s : 0) ;
+}
+
+
+/* ========================================================================== */
+/* === colamd_set_defaults ================================================== */
+/* ========================================================================== */
+
+/*
+    The colamd_set_defaults routine sets the default values of the user-
+    controllable parameters for colamd and symamd:
+
+	Colamd: rows with more than max (16, knobs [0] * sqrt (n_col))
+	entries are removed prior to ordering.  Columns with more than
+	max (16, knobs [1] * sqrt (MIN (n_row,n_col))) entries are removed
+	prior to ordering, and placed last in the output column ordering. 
+
+	Symamd: Rows and columns with more than max (16, knobs [0] * sqrt (n))
+	entries are removed prior to ordering, and placed last in the
+	output ordering.
+
+	knobs [0]	dense row control
+
+	knobs [1]	dense column control
+
+	knobs [2]	if nonzero, do aggresive absorption
+
+	knobs [3..19]	unused, but future versions might use this
+
+*/
+
+void COLAMD_set_defaults
+(
+    /* === Parameters ======================================================= */
+
+    double knobs [COLAMD_KNOBS]		/* knob array */
+)
+{
+    /* === Local variables ================================================== */
+
+    Int i ;
+
+    if (!knobs)
+    {
+	return ;			/* no knobs to initialize */
+    }
+    for (i = 0 ; i < COLAMD_KNOBS ; i++)
+    {
+	knobs [i] = 0 ;
+    }
+    knobs [COLAMD_DENSE_ROW] = 10 ;
+    knobs [COLAMD_DENSE_COL] = 10 ;
+    knobs [COLAMD_AGGRESSIVE] = TRUE ;	/* default: do aggressive absorption*/
+}
+
+
+/* ========================================================================== */
+/* === symamd =============================================================== */
+/* ========================================================================== */
+
+int SYMAMD_MAIN			/* return TRUE if OK, FALSE otherwise */
+(
+    /* === Parameters ======================================================= */
+
+    Int n,				/* number of rows and columns of A */
+    Int A [],				/* row indices of A */
+    Int p [],				/* column pointers of A */
+    Int perm [],			/* output permutation, size n+1 */
+    double knobs [COLAMD_KNOBS],	/* parameters (uses defaults if NULL) */
+    Int stats [COLAMD_STATS],		/* output statistics and error codes */
+    void * (*allocate) (size_t, size_t),
+    					/* pointer to calloc (ANSI C) or */
+					/* mxCalloc (for MATLAB mexFunction) */
+    void (*release) (void *)
+    					/* pointer to free (ANSI C) or */
+    					/* mxFree (for MATLAB mexFunction) */
+)
+{
+    /* === Local variables ================================================== */
+
+    Int *count ;		/* length of each column of M, and col pointer*/
+    Int *mark ;			/* mark array for finding duplicate entries */
+    Int *M ;			/* row indices of matrix M */
+    size_t Mlen ;		/* length of M */
+    Int n_row ;			/* number of rows in M */
+    Int nnz ;			/* number of entries in A */
+    Int i ;			/* row index of A */
+    Int j ;			/* column index of A */
+    Int k ;			/* row index of M */ 
+    Int mnz ;			/* number of nonzeros in M */
+    Int pp ;			/* index into a column of A */
+    Int last_row ;		/* last row seen in the current column */
+    Int length ;		/* number of nonzeros in a column */
+
+    double cknobs [COLAMD_KNOBS] ;		/* knobs for colamd */
+    double default_knobs [COLAMD_KNOBS] ;	/* default knobs for colamd */
+
+#ifndef NDEBUG
+    colamd_get_debug ("symamd") ;
+#endif /* NDEBUG */
+
+    /* === Check the input arguments ======================================== */
+
+    if (!stats)
+    {
+	DEBUG0 (("symamd: stats not present\n")) ;
+	return (FALSE) ;
+    }
+    for (i = 0 ; i < COLAMD_STATS ; i++)
+    {
+	stats [i] = 0 ;
+    }
+    stats [COLAMD_STATUS] = COLAMD_OK ;
+    stats [COLAMD_INFO1] = -1 ;
+    stats [COLAMD_INFO2] = -1 ;
+
+    if (!A)
+    {
+    	stats [COLAMD_STATUS] = COLAMD_ERROR_A_not_present ;
+	DEBUG0 (("symamd: A not present\n")) ;
+	return (FALSE) ;
+    }
+
+    if (!p)		/* p is not present */
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_p_not_present ;
+	DEBUG0 (("symamd: p not present\n")) ;
+    	return (FALSE) ;
+    }
+
+    if (n < 0)		/* n must be >= 0 */
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_ncol_negative ;
+	stats [COLAMD_INFO1] = n ;
+	DEBUG0 (("symamd: n negative %d\n", n)) ;
+    	return (FALSE) ;
+    }
+
+    nnz = p [n] ;
+    if (nnz < 0)	/* nnz must be >= 0 */
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_nnz_negative ;
+	stats [COLAMD_INFO1] = nnz ;
+	DEBUG0 (("symamd: number of entries negative %d\n", nnz)) ;
+	return (FALSE) ;
+    }
+
+    if (p [0] != 0)
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_p0_nonzero ;
+	stats [COLAMD_INFO1] = p [0] ;
+	DEBUG0 (("symamd: p[0] not zero %d\n", p [0])) ;
+	return (FALSE) ;
+    }
+
+    /* === If no knobs, set default knobs =================================== */
+
+    if (!knobs)
+    {
+	COLAMD_set_defaults (default_knobs) ;
+	knobs = default_knobs ;
+    }
+
+    /* === Allocate count and mark ========================================== */
+
+    count = (Int *) ((*allocate) (n+1, sizeof (Int))) ;
+    if (!count)
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_out_of_memory ;
+	DEBUG0 (("symamd: allocate count (size %d) failed\n", n+1)) ;
+	return (FALSE) ;
+    }
+
+    mark = (Int *) ((*allocate) (n+1, sizeof (Int))) ;
+    if (!mark)
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_out_of_memory ;
+	(*release) ((void *) count) ;
+	DEBUG0 (("symamd: allocate mark (size %d) failed\n", n+1)) ;
+	return (FALSE) ;
+    }
+
+    /* === Compute column counts of M, check if A is valid ================== */
+
+    stats [COLAMD_INFO3] = 0 ;  /* number of duplicate or unsorted row indices*/
+
+    for (i = 0 ; i < n ; i++)
+    {
+    	mark [i] = -1 ;
+    }
+
+    for (j = 0 ; j < n ; j++)
+    {
+	last_row = -1 ;
+
+	length = p [j+1] - p [j] ;
+	if (length < 0)
+	{
+	    /* column pointers must be non-decreasing */
+	    stats [COLAMD_STATUS] = COLAMD_ERROR_col_length_negative ;
+	    stats [COLAMD_INFO1] = j ;
+	    stats [COLAMD_INFO2] = length ;
+	    (*release) ((void *) count) ;
+	    (*release) ((void *) mark) ;
+	    DEBUG0 (("symamd: col %d negative length %d\n", j, length)) ;
+	    return (FALSE) ;
+	}
+
+	for (pp = p [j] ; pp < p [j+1] ; pp++)
+	{
+	    i = A [pp] ;
+	    if (i < 0 || i >= n)
+	    {
+		/* row index i, in column j, is out of bounds */
+		stats [COLAMD_STATUS] = COLAMD_ERROR_row_index_out_of_bounds ;
+		stats [COLAMD_INFO1] = j ;
+		stats [COLAMD_INFO2] = i ;
+		stats [COLAMD_INFO3] = n ;
+		(*release) ((void *) count) ;
+		(*release) ((void *) mark) ;
+		DEBUG0 (("symamd: row %d col %d out of bounds\n", i, j)) ;
+		return (FALSE) ;
+	    }
+
+	    if (i <= last_row || mark [i] == j)
+	    {
+		/* row index is unsorted or repeated (or both), thus col */
+		/* is jumbled.  This is a notice, not an error condition. */
+		stats [COLAMD_STATUS] = COLAMD_OK_BUT_JUMBLED ;
+		stats [COLAMD_INFO1] = j ;
+		stats [COLAMD_INFO2] = i ;
+		(stats [COLAMD_INFO3]) ++ ;
+		DEBUG1 (("symamd: row %d col %d unsorted/duplicate\n", i, j)) ;
+	    }
+
+	    if (i > j && mark [i] != j)
+	    {
+		/* row k of M will contain column indices i and j */
+		count [i]++ ;
+		count [j]++ ;
+	    }
+
+	    /* mark the row as having been seen in this column */
+	    mark [i] = j ;
+
+	    last_row = i ;
+	}
+    }
+
+    /* v2.4: removed free(mark) */
+
+    /* === Compute column pointers of M ===================================== */
+
+    /* use output permutation, perm, for column pointers of M */
+    perm [0] = 0 ;
+    for (j = 1 ; j <= n ; j++)
+    {
+	perm [j] = perm [j-1] + count [j-1] ;
+    }
+    for (j = 0 ; j < n ; j++)
+    {
+	count [j] = perm [j] ;
+    }
+
+    /* === Construct M ====================================================== */
+
+    mnz = perm [n] ;
+    n_row = mnz / 2 ;
+    Mlen = COLAMD_recommended (mnz, n_row, n) ;
+    M = (Int *) ((*allocate) (Mlen, sizeof (Int))) ;
+    DEBUG0 (("symamd: M is %d-by-%d with %d entries, Mlen = %g\n",
+    	n_row, n, mnz, (double) Mlen)) ;
+
+    if (!M)
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_out_of_memory ;
+	(*release) ((void *) count) ;
+	(*release) ((void *) mark) ;
+	DEBUG0 (("symamd: allocate M (size %g) failed\n", (double) Mlen)) ;
+	return (FALSE) ;
+    }
+
+    k = 0 ;
+
+    if (stats [COLAMD_STATUS] == COLAMD_OK)
+    {
+	/* Matrix is OK */
+	for (j = 0 ; j < n ; j++)
+	{
+	    ASSERT (p [j+1] - p [j] >= 0) ;
+	    for (pp = p [j] ; pp < p [j+1] ; pp++)
+	    {
+		i = A [pp] ;
+		ASSERT (i >= 0 && i < n) ;
+		if (i > j)
+		{
+		    /* row k of M contains column indices i and j */
+		    M [count [i]++] = k ;
+		    M [count [j]++] = k ;
+		    k++ ;
+		}
+	    }
+	}
+    }
+    else
+    {
+	/* Matrix is jumbled.  Do not add duplicates to M.  Unsorted cols OK. */
+	DEBUG0 (("symamd: Duplicates in A.\n")) ;
+	for (i = 0 ; i < n ; i++)
+	{
+	    mark [i] = -1 ;
+	}
+	for (j = 0 ; j < n ; j++)
+	{
+	    ASSERT (p [j+1] - p [j] >= 0) ;
+	    for (pp = p [j] ; pp < p [j+1] ; pp++)
+	    {
+		i = A [pp] ;
+		ASSERT (i >= 0 && i < n) ;
+		if (i > j && mark [i] != j)
+		{
+		    /* row k of M contains column indices i and j */
+		    M [count [i]++] = k ;
+		    M [count [j]++] = k ;
+		    k++ ;
+		    mark [i] = j ;
+		}
+	    }
+	}
+	/* v2.4: free(mark) moved below */
+    }
+
+    /* count and mark no longer needed */
+    (*release) ((void *) count) ;
+    (*release) ((void *) mark) ;	/* v2.4: free (mark) moved here */
+    ASSERT (k == n_row) ;
+
+    /* === Adjust the knobs for M =========================================== */
+
+    for (i = 0 ; i < COLAMD_KNOBS ; i++)
+    {
+	cknobs [i] = knobs [i] ;
+    }
+
+    /* there are no dense rows in M */
+    cknobs [COLAMD_DENSE_ROW] = -1 ;
+    cknobs [COLAMD_DENSE_COL] = knobs [COLAMD_DENSE_ROW] ;
+
+    /* === Order the columns of M =========================================== */
+
+    /* v2.4: colamd cannot fail here, so the error check is removed */
+    (void) COLAMD_MAIN (n_row, n, (Int) Mlen, M, perm, cknobs, stats) ;
+
+    /* Note that the output permutation is now in perm */
+
+    /* === get the statistics for symamd from colamd ======================== */
+
+    /* a dense column in colamd means a dense row and col in symamd */
+    stats [COLAMD_DENSE_ROW] = stats [COLAMD_DENSE_COL] ;
+
+    /* === Free M =========================================================== */
+
+    (*release) ((void *) M) ;
+    DEBUG0 (("symamd: done.\n")) ;
+    return (TRUE) ;
+
+}
+
+/* ========================================================================== */
+/* === colamd =============================================================== */
+/* ========================================================================== */
+
+/*
+    The colamd routine computes a column ordering Q of a sparse matrix
+    A such that the LU factorization P(AQ) = LU remains sparse, where P is
+    selected via partial pivoting.   The routine can also be viewed as
+    providing a permutation Q such that the Cholesky factorization
+    (AQ)'(AQ) = LL' remains sparse.
+*/
+
+int COLAMD_MAIN		/* returns TRUE if successful, FALSE otherwise*/
+(
+    /* === Parameters ======================================================= */
+
+    Int n_row,			/* number of rows in A */
+    Int n_col,			/* number of columns in A */
+    Int Alen,			/* length of A */
+    Int A [],			/* row indices of A */
+    Int p [],			/* pointers to columns in A */
+    double knobs [COLAMD_KNOBS],/* parameters (uses defaults if NULL) */
+    Int stats [COLAMD_STATS]	/* output statistics and error codes */
+)
+{
+    /* === Local variables ================================================== */
+
+    Int i ;			/* loop index */
+    Int nnz ;			/* nonzeros in A */
+    size_t Row_size ;		/* size of Row [], in integers */
+    size_t Col_size ;		/* size of Col [], in integers */
+    size_t need ;		/* minimum required length of A */
+    Colamd_Row *Row ;		/* pointer into A of Row [0..n_row] array */
+    Colamd_Col *Col ;		/* pointer into A of Col [0..n_col] array */
+    Int n_col2 ;		/* number of non-dense, non-empty columns */
+    Int n_row2 ;		/* number of non-dense, non-empty rows */
+    Int ngarbage ;		/* number of garbage collections performed */
+    Int max_deg ;		/* maximum row degree */
+    double default_knobs [COLAMD_KNOBS] ;	/* default knobs array */
+    Int aggressive ;		/* do aggressive absorption */
+    int ok ;
+
+#ifndef NDEBUG
+    colamd_get_debug ("colamd") ;
+#endif /* NDEBUG */
+
+    /* === Check the input arguments ======================================== */
+
+    if (!stats)
+    {
+	DEBUG0 (("colamd: stats not present\n")) ;
+	return (FALSE) ;
+    }
+    for (i = 0 ; i < COLAMD_STATS ; i++)
+    {
+	stats [i] = 0 ;
+    }
+    stats [COLAMD_STATUS] = COLAMD_OK ;
+    stats [COLAMD_INFO1] = -1 ;
+    stats [COLAMD_INFO2] = -1 ;
+
+    if (!A)		/* A is not present */
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_A_not_present ;
+	DEBUG0 (("colamd: A not present\n")) ;
+	return (FALSE) ;
+    }
+
+    if (!p)		/* p is not present */
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_p_not_present ;
+	DEBUG0 (("colamd: p not present\n")) ;
+    	return (FALSE) ;
+    }
+
+    if (n_row < 0)	/* n_row must be >= 0 */
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_nrow_negative ;
+	stats [COLAMD_INFO1] = n_row ;
+	DEBUG0 (("colamd: nrow negative %d\n", n_row)) ;
+    	return (FALSE) ;
+    }
+
+    if (n_col < 0)	/* n_col must be >= 0 */
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_ncol_negative ;
+	stats [COLAMD_INFO1] = n_col ;
+	DEBUG0 (("colamd: ncol negative %d\n", n_col)) ;
+    	return (FALSE) ;
+    }
+
+    nnz = p [n_col] ;
+    if (nnz < 0)	/* nnz must be >= 0 */
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_nnz_negative ;
+	stats [COLAMD_INFO1] = nnz ;
+	DEBUG0 (("colamd: number of entries negative %d\n", nnz)) ;
+	return (FALSE) ;
+    }
+
+    if (p [0] != 0)
+    {
+	stats [COLAMD_STATUS] = COLAMD_ERROR_p0_nonzero	;
+	stats [COLAMD_INFO1] = p [0] ;
+	DEBUG0 (("colamd: p[0] not zero %d\n", p [0])) ;
+	return (FALSE) ;
+    }
+
+    /* === If no knobs, set default knobs =================================== */
+
+    if (!knobs)
+    {
+	COLAMD_set_defaults (default_knobs) ;
+	knobs = default_knobs ;
+    }
+
+    aggressive = (knobs [COLAMD_AGGRESSIVE] != FALSE) ;
+
+    /* === Allocate the Row and Col arrays from array A ===================== */
+
+    ok = TRUE ;
+    Col_size = COLAMD_C (n_col, &ok) ;	    /* size of Col array of structs */
+    Row_size = COLAMD_R (n_row, &ok) ;	    /* size of Row array of structs */
+
+    /* need = 2*nnz + n_col + Col_size + Row_size ; */
+    need = t_mult (nnz, 2, &ok) ;
+    need = t_add (need, n_col, &ok) ;
+    need = t_add (need, Col_size, &ok) ;
+    need = t_add (need, Row_size, &ok) ;
+
+    if (!ok || need > (size_t) Alen)
+    {
+	/* not enough space in array A to perform the ordering */
+	stats [COLAMD_STATUS] = COLAMD_ERROR_A_too_small ;
+	stats [COLAMD_INFO1] = need ;
+	stats [COLAMD_INFO2] = Alen ;
+	DEBUG0 (("colamd: Need Alen >= %d, given only Alen = %d\n", need,Alen));
+	return (FALSE) ;
+    }
+
+    Alen -= Col_size + Row_size ;
+    Col = (Colamd_Col *) &A [Alen] ;
+    Row = (Colamd_Row *) &A [Alen + Col_size] ;
+
+    /* === Construct the row and column data structures ===================== */
+
+    if (!init_rows_cols (n_row, n_col, Row, Col, A, p, stats))
+    {
+	/* input matrix is invalid */
+	DEBUG0 (("colamd: Matrix invalid\n")) ;
+	return (FALSE) ;
+    }
+
+    /* === Initialize scores, kill dense rows/columns ======================= */
+
+    init_scoring (n_row, n_col, Row, Col, A, p, knobs,
+	&n_row2, &n_col2, &max_deg) ;
+
+    /* === Order the supercolumns =========================================== */
+
+    ngarbage = find_ordering (n_row, n_col, Alen, Row, Col, A, p,
+	n_col2, max_deg, 2*nnz, aggressive) ;
+
+    /* === Order the non-principal columns ================================== */
+
+    order_children (n_col, Col, p) ;
+
+    /* === Return statistics in stats ======================================= */
+
+    stats [COLAMD_DENSE_ROW] = n_row - n_row2 ;
+    stats [COLAMD_DENSE_COL] = n_col - n_col2 ;
+    stats [COLAMD_DEFRAG_COUNT] = ngarbage ;
+    DEBUG0 (("colamd: done.\n")) ; 
+    return (TRUE) ;
+}
+
+
+/* ========================================================================== */
+/* === colamd_report ======================================================== */
+/* ========================================================================== */
+
+void COLAMD_report
+(
+    Int stats [COLAMD_STATS]
+)
+{
+    print_report ("colamd", stats) ;
+}
+
+
+/* ========================================================================== */
+/* === symamd_report ======================================================== */
+/* ========================================================================== */
+
+void SYMAMD_report
+(
+    Int stats [COLAMD_STATS]
+)
+{
+    print_report ("symamd", stats) ;
+}
+
+
+
+/* ========================================================================== */
+/* === NON-USER-CALLABLE ROUTINES: ========================================== */
+/* ========================================================================== */
+
+/* There are no user-callable routines beyond this point in the file */
+
+
+/* ========================================================================== */
+/* === init_rows_cols ======================================================= */
+/* ========================================================================== */
+
+/*
+    Takes the column form of the matrix in A and creates the row form of the
+    matrix.  Also, row and column attributes are stored in the Col and Row
+    structs.  If the columns are un-sorted or contain duplicate row indices,
+    this routine will also sort and remove duplicate row indices from the
+    column form of the matrix.  Returns FALSE if the matrix is invalid,
+    TRUE otherwise.  Not user-callable.
+*/
+
+PRIVATE Int init_rows_cols	/* returns TRUE if OK, or FALSE otherwise */
+(
+    /* === Parameters ======================================================= */
+
+    Int n_row,			/* number of rows of A */
+    Int n_col,			/* number of columns of A */
+    Colamd_Row Row [],		/* of size n_row+1 */
+    Colamd_Col Col [],		/* of size n_col+1 */
+    Int A [],			/* row indices of A, of size Alen */
+    Int p [],			/* pointers to columns in A, of size n_col+1 */
+    Int stats [COLAMD_STATS]	/* colamd statistics */ 
+)
+{
+    /* === Local variables ================================================== */
+
+    Int col ;			/* a column index */
+    Int row ;			/* a row index */
+    Int *cp ;			/* a column pointer */
+    Int *cp_end ;		/* a pointer to the end of a column */
+    Int *rp ;			/* a row pointer */
+    Int *rp_end ;		/* a pointer to the end of a row */
+    Int last_row ;		/* previous row */
+
+    /* === Initialize columns, and check column pointers ==================== */
+
+    for (col = 0 ; col < n_col ; col++)
+    {
+	Col [col].start = p [col] ;
+	Col [col].length = p [col+1] - p [col] ;
+
+	if (Col [col].length < 0)
+	{
+	    /* column pointers must be non-decreasing */
+	    stats [COLAMD_STATUS] = COLAMD_ERROR_col_length_negative ;
+	    stats [COLAMD_INFO1] = col ;
+	    stats [COLAMD_INFO2] = Col [col].length ;
+	    DEBUG0 (("colamd: col %d length %d < 0\n", col, Col [col].length)) ;
+	    return (FALSE) ;
+	}
+
+	Col [col].shared1.thickness = 1 ;
+	Col [col].shared2.score = 0 ;
+	Col [col].shared3.prev = EMPTY ;
+	Col [col].shared4.degree_next = EMPTY ;
+    }
+
+    /* p [0..n_col] no longer needed, used as "head" in subsequent routines */
+
+    /* === Scan columns, compute row degrees, and check row indices ========= */
+
+    stats [COLAMD_INFO3] = 0 ;	/* number of duplicate or unsorted row indices*/
+
+    for (row = 0 ; row < n_row ; row++)
+    {
+	Row [row].length = 0 ;
+	Row [row].shared2.mark = -1 ;
+    }
+
+    for (col = 0 ; col < n_col ; col++)
+    {
+	last_row = -1 ;
+
+	cp = &A [p [col]] ;
+	cp_end = &A [p [col+1]] ;
+
+	while (cp < cp_end)
+	{
+	    row = *cp++ ;
+
+	    /* make sure row indices within range */
+	    if (row < 0 || row >= n_row)
+	    {
+		stats [COLAMD_STATUS] = COLAMD_ERROR_row_index_out_of_bounds ;
+		stats [COLAMD_INFO1] = col ;
+		stats [COLAMD_INFO2] = row ;
+		stats [COLAMD_INFO3] = n_row ;
+		DEBUG0 (("colamd: row %d col %d out of bounds\n", row, col)) ;
+		return (FALSE) ;
+	    }
+
+	    if (row <= last_row || Row [row].shared2.mark == col)
+	    {
+		/* row index are unsorted or repeated (or both), thus col */
+		/* is jumbled.  This is a notice, not an error condition. */
+		stats [COLAMD_STATUS] = COLAMD_OK_BUT_JUMBLED ;
+		stats [COLAMD_INFO1] = col ;
+		stats [COLAMD_INFO2] = row ;
+		(stats [COLAMD_INFO3]) ++ ;
+		DEBUG1 (("colamd: row %d col %d unsorted/duplicate\n",row,col));
+	    }
+
+	    if (Row [row].shared2.mark != col)
+	    {
+		Row [row].length++ ;
+	    }
+	    else
+	    {
+		/* this is a repeated entry in the column, */
+		/* it will be removed */
+		Col [col].length-- ;
+	    }
+
+	    /* mark the row as having been seen in this column */
+	    Row [row].shared2.mark = col ;
+
+	    last_row = row ;
+	}
+    }
+
+    /* === Compute row pointers ============================================= */
+
+    /* row form of the matrix starts directly after the column */
+    /* form of matrix in A */
+    Row [0].start = p [n_col] ;
+    Row [0].shared1.p = Row [0].start ;
+    Row [0].shared2.mark = -1 ;
+    for (row = 1 ; row < n_row ; row++)
+    {
+	Row [row].start = Row [row-1].start + Row [row-1].length ;
+	Row [row].shared1.p = Row [row].start ;
+	Row [row].shared2.mark = -1 ;
+    }
+
+    /* === Create row form ================================================== */
+
+    if (stats [COLAMD_STATUS] == COLAMD_OK_BUT_JUMBLED)
+    {
+	/* if cols jumbled, watch for repeated row indices */
+	for (col = 0 ; col < n_col ; col++)
+	{
+	    cp = &A [p [col]] ;
+	    cp_end = &A [p [col+1]] ;
+	    while (cp < cp_end)
+	    {
+		row = *cp++ ;
+		if (Row [row].shared2.mark != col)
+		{
+		    A [(Row [row].shared1.p)++] = col ;
+		    Row [row].shared2.mark = col ;
+		}
+	    }
+	}
+    }
+    else
+    {
+	/* if cols not jumbled, we don't need the mark (this is faster) */
+	for (col = 0 ; col < n_col ; col++)
+	{
+	    cp = &A [p [col]] ;
+	    cp_end = &A [p [col+1]] ;
+	    while (cp < cp_end)
+	    {
+		A [(Row [*cp++].shared1.p)++] = col ;
+	    }
+	}
+    }
+
+    /* === Clear the row marks and set row degrees ========================== */
+
+    for (row = 0 ; row < n_row ; row++)
+    {
+	Row [row].shared2.mark = 0 ;
+	Row [row].shared1.degree = Row [row].length ;
+    }
+
+    /* === See if we need to re-create columns ============================== */
+
+    if (stats [COLAMD_STATUS] == COLAMD_OK_BUT_JUMBLED)
+    {
+    	DEBUG0 (("colamd: reconstructing column form, matrix jumbled\n")) ;
+
+#ifndef NDEBUG
+	/* make sure column lengths are correct */
+	for (col = 0 ; col < n_col ; col++)
+	{
+	    p [col] = Col [col].length ;
+	}
+	for (row = 0 ; row < n_row ; row++)
+	{
+	    rp = &A [Row [row].start] ;
+	    rp_end = rp + Row [row].length ;
+	    while (rp < rp_end)
+	    {
+		p [*rp++]-- ;
+	    }
+	}
+	for (col = 0 ; col < n_col ; col++)
+	{
+	    ASSERT (p [col] == 0) ;
+	}
+	/* now p is all zero (different than when debugging is turned off) */
+#endif /* NDEBUG */
+
+	/* === Compute col pointers ========================================= */
+
+	/* col form of the matrix starts at A [0]. */
+	/* Note, we may have a gap between the col form and the row */
+	/* form if there were duplicate entries, if so, it will be */
+	/* removed upon the first garbage collection */
+	Col [0].start = 0 ;
+	p [0] = Col [0].start ;
+	for (col = 1 ; col < n_col ; col++)
+	{
+	    /* note that the lengths here are for pruned columns, i.e. */
+	    /* no duplicate row indices will exist for these columns */
+	    Col [col].start = Col [col-1].start + Col [col-1].length ;
+	    p [col] = Col [col].start ;
+	}
+
+	/* === Re-create col form =========================================== */
+
+	for (row = 0 ; row < n_row ; row++)
+	{
+	    rp = &A [Row [row].start] ;
+	    rp_end = rp + Row [row].length ;
+	    while (rp < rp_end)
+	    {
+		A [(p [*rp++])++] = row ;
+	    }
+	}
+    }
+
+    /* === Done.  Matrix is not (or no longer) jumbled ====================== */
+
+    return (TRUE) ;
+}
+
+
+/* ========================================================================== */
+/* === init_scoring ========================================================= */
+/* ========================================================================== */
+
+/*
+    Kills dense or empty columns and rows, calculates an initial score for
+    each column, and places all columns in the degree lists.  Not user-callable.
+*/
+
+PRIVATE void init_scoring
+(
+    /* === Parameters ======================================================= */
+
+    Int n_row,			/* number of rows of A */
+    Int n_col,			/* number of columns of A */
+    Colamd_Row Row [],		/* of size n_row+1 */
+    Colamd_Col Col [],		/* of size n_col+1 */
+    Int A [],			/* column form and row form of A */
+    Int head [],		/* of size n_col+1 */
+    double knobs [COLAMD_KNOBS],/* parameters */
+    Int *p_n_row2,		/* number of non-dense, non-empty rows */
+    Int *p_n_col2,		/* number of non-dense, non-empty columns */
+    Int *p_max_deg		/* maximum row degree */
+)
+{
+    /* === Local variables ================================================== */
+
+    Int c ;			/* a column index */
+    Int r, row ;		/* a row index */
+    Int *cp ;			/* a column pointer */
+    Int deg ;			/* degree of a row or column */
+    Int *cp_end ;		/* a pointer to the end of a column */
+    Int *new_cp ;		/* new column pointer */
+    Int col_length ;		/* length of pruned column */
+    Int score ;			/* current column score */
+    Int n_col2 ;		/* number of non-dense, non-empty columns */
+    Int n_row2 ;		/* number of non-dense, non-empty rows */
+    Int dense_row_count ;	/* remove rows with more entries than this */
+    Int dense_col_count ;	/* remove cols with more entries than this */
+    Int min_score ;		/* smallest column score */
+    Int max_deg ;		/* maximum row degree */
+    Int next_col ;		/* Used to add to degree list.*/
+
+#ifndef NDEBUG
+    Int debug_count ;		/* debug only. */
+#endif /* NDEBUG */
+
+    /* === Extract knobs ==================================================== */
+
+    /* Note: if knobs contains a NaN, this is undefined: */
+    if (knobs [COLAMD_DENSE_ROW] < 0)
+    {
+	/* only remove completely dense rows */
+	dense_row_count = n_col-1 ;
+    }
+    else
+    {
+	dense_row_count = DENSE_DEGREE (knobs [COLAMD_DENSE_ROW], n_col) ;
+    }
+    if (knobs [COLAMD_DENSE_COL] < 0)
+    {
+	/* only remove completely dense columns */
+	dense_col_count = n_row-1 ;
+    }
+    else
+    {
+	dense_col_count =
+	    DENSE_DEGREE (knobs [COLAMD_DENSE_COL], MIN (n_row, n_col)) ;
+    }
+
+    DEBUG1 (("colamd: densecount: %d %d\n", dense_row_count, dense_col_count)) ;
+    max_deg = 0 ;
+    n_col2 = n_col ;
+    n_row2 = n_row ;
+
+    /* === Kill empty columns =============================================== */
+
+    /* Put the empty columns at the end in their natural order, so that LU */
+    /* factorization can proceed as far as possible. */
+    for (c = n_col-1 ; c >= 0 ; c--)
+    {
+	deg = Col [c].length ;
+	if (deg == 0)
+	{
+	    /* this is a empty column, kill and order it last */
+	    Col [c].shared2.order = --n_col2 ;
+	    KILL_PRINCIPAL_COL (c) ;
+	}
+    }
+    DEBUG1 (("colamd: null columns killed: %d\n", n_col - n_col2)) ;
+
+    /* === Kill dense columns =============================================== */
+
+    /* Put the dense columns at the end, in their natural order */
+    for (c = n_col-1 ; c >= 0 ; c--)
+    {
+	/* skip any dead columns */
+	if (COL_IS_DEAD (c))
+	{
+	    continue ;
+	}
+	deg = Col [c].length ;
+	if (deg > dense_col_count)
+	{
+	    /* this is a dense column, kill and order it last */
+	    Col [c].shared2.order = --n_col2 ;
+	    /* decrement the row degrees */
+	    cp = &A [Col [c].start] ;
+	    cp_end = cp + Col [c].length ;
+	    while (cp < cp_end)
+	    {
+		Row [*cp++].shared1.degree-- ;
+	    }
+	    KILL_PRINCIPAL_COL (c) ;
+	}
+    }
+    DEBUG1 (("colamd: Dense and null columns killed: %d\n", n_col - n_col2)) ;
+
+    /* === Kill dense and empty rows ======================================== */
+
+    for (r = 0 ; r < n_row ; r++)
+    {
+	deg = Row [r].shared1.degree ;
+	ASSERT (deg >= 0 && deg <= n_col) ;
+	if (deg > dense_row_count || deg == 0)
+	{
+	    /* kill a dense or empty row */
+	    KILL_ROW (r) ;
+	    --n_row2 ;
+	}
+	else
+	{
+	    /* keep track of max degree of remaining rows */
+	    max_deg = MAX (max_deg, deg) ;
+	}
+    }
+    DEBUG1 (("colamd: Dense and null rows killed: %d\n", n_row - n_row2)) ;
+
+    /* === Compute initial column scores ==================================== */
+
+    /* At this point the row degrees are accurate.  They reflect the number */
+    /* of "live" (non-dense) columns in each row.  No empty rows exist. */
+    /* Some "live" columns may contain only dead rows, however.  These are */
+    /* pruned in the code below. */
+
+    /* now find the initial matlab score for each column */
+    for (c = n_col-1 ; c >= 0 ; c--)
+    {
+	/* skip dead column */
+	if (COL_IS_DEAD (c))
+	{
+	    continue ;
+	}
+	score = 0 ;
+	cp = &A [Col [c].start] ;
+	new_cp = cp ;
+	cp_end = cp + Col [c].length ;
+	while (cp < cp_end)
+	{
+	    /* get a row */
+	    row = *cp++ ;
+	    /* skip if dead */
+	    if (ROW_IS_DEAD (row))
+	    {
+		continue ;
+	    }
+	    /* compact the column */
+	    *new_cp++ = row ;
+	    /* add row's external degree */
+	    score += Row [row].shared1.degree - 1 ;
+	    /* guard against integer overflow */
+	    score = MIN (score, n_col) ;
+	}
+	/* determine pruned column length */
+	col_length = (Int) (new_cp - &A [Col [c].start]) ;
+	if (col_length == 0)
+	{
+	    /* a newly-made null column (all rows in this col are "dense" */
+	    /* and have already been killed) */
+	    DEBUG2 (("Newly null killed: %d\n", c)) ;
+	    Col [c].shared2.order = --n_col2 ;
+	    KILL_PRINCIPAL_COL (c) ;
+	}
+	else
+	{
+	    /* set column length and set score */
+	    ASSERT (score >= 0) ;
+	    ASSERT (score <= n_col) ;
+	    Col [c].length = col_length ;
+	    Col [c].shared2.score = score ;
+	}
+    }
+    DEBUG1 (("colamd: Dense, null, and newly-null columns killed: %d\n",
+    	n_col-n_col2)) ;
+
+    /* At this point, all empty rows and columns are dead.  All live columns */
+    /* are "clean" (containing no dead rows) and simplicial (no supercolumns */
+    /* yet).  Rows may contain dead columns, but all live rows contain at */
+    /* least one live column. */
+
+#ifndef NDEBUG
+    debug_structures (n_row, n_col, Row, Col, A, n_col2) ;
+#endif /* NDEBUG */
+
+    /* === Initialize degree lists ========================================== */
+
+#ifndef NDEBUG
+    debug_count = 0 ;
+#endif /* NDEBUG */
+
+    /* clear the hash buckets */
+    for (c = 0 ; c <= n_col ; c++)
+    {
+	head [c] = EMPTY ;
+    }
+    min_score = n_col ;
+    /* place in reverse order, so low column indices are at the front */
+    /* of the lists.  This is to encourage natural tie-breaking */
+    for (c = n_col-1 ; c >= 0 ; c--)
+    {
+	/* only add principal columns to degree lists */
+	if (COL_IS_ALIVE (c))
+	{
+	    DEBUG4 (("place %d score %d minscore %d ncol %d\n",
+		c, Col [c].shared2.score, min_score, n_col)) ;
+
+	    /* === Add columns score to DList =============================== */
+
+	    score = Col [c].shared2.score ;
+
+	    ASSERT (min_score >= 0) ;
+	    ASSERT (min_score <= n_col) ;
+	    ASSERT (score >= 0) ;
+	    ASSERT (score <= n_col) ;
+	    ASSERT (head [score] >= EMPTY) ;
+
+	    /* now add this column to dList at proper score location */
+	    next_col = head [score] ;
+	    Col [c].shared3.prev = EMPTY ;
+	    Col [c].shared4.degree_next = next_col ;
+
+	    /* if there already was a column with the same score, set its */
+	    /* previous pointer to this new column */
+	    if (next_col != EMPTY)
+	    {
+		Col [next_col].shared3.prev = c ;
+	    }
+	    head [score] = c ;
+
+	    /* see if this score is less than current min */
+	    min_score = MIN (min_score, score) ;
+
+#ifndef NDEBUG
+	    debug_count++ ;
+#endif /* NDEBUG */
+
+	}
+    }
+
+#ifndef NDEBUG
+    DEBUG1 (("colamd: Live cols %d out of %d, non-princ: %d\n",
+	debug_count, n_col, n_col-debug_count)) ;
+    ASSERT (debug_count == n_col2) ;
+    debug_deg_lists (n_row, n_col, Row, Col, head, min_score, n_col2, max_deg) ;
+#endif /* NDEBUG */
+
+    /* === Return number of remaining columns, and max row degree =========== */
+
+    *p_n_col2 = n_col2 ;
+    *p_n_row2 = n_row2 ;
+    *p_max_deg = max_deg ;
+}
+
+
+/* ========================================================================== */
+/* === find_ordering ======================================================== */
+/* ========================================================================== */
+
+/*
+    Order the principal columns of the supercolumn form of the matrix
+    (no supercolumns on input).  Uses a minimum approximate column minimum
+    degree ordering method.  Not user-callable.
+*/
+
+PRIVATE Int find_ordering	/* return the number of garbage collections */
+(
+    /* === Parameters ======================================================= */
+
+    Int n_row,			/* number of rows of A */
+    Int n_col,			/* number of columns of A */
+    Int Alen,			/* size of A, 2*nnz + n_col or larger */
+    Colamd_Row Row [],		/* of size n_row+1 */
+    Colamd_Col Col [],		/* of size n_col+1 */
+    Int A [],			/* column form and row form of A */
+    Int head [],		/* of size n_col+1 */
+    Int n_col2,			/* Remaining columns to order */
+    Int max_deg,		/* Maximum row degree */
+    Int pfree,			/* index of first free slot (2*nnz on entry) */
+    Int aggressive
+)
+{
+    /* === Local variables ================================================== */
+
+    Int k ;			/* current pivot ordering step */
+    Int pivot_col ;		/* current pivot column */
+    Int *cp ;			/* a column pointer */
+    Int *rp ;			/* a row pointer */
+    Int pivot_row ;		/* current pivot row */
+    Int *new_cp ;		/* modified column pointer */
+    Int *new_rp ;		/* modified row pointer */
+    Int pivot_row_start ;	/* pointer to start of pivot row */
+    Int pivot_row_degree ;	/* number of columns in pivot row */
+    Int pivot_row_length ;	/* number of supercolumns in pivot row */
+    Int pivot_col_score ;	/* score of pivot column */
+    Int needed_memory ;		/* free space needed for pivot row */
+    Int *cp_end ;		/* pointer to the end of a column */
+    Int *rp_end ;		/* pointer to the end of a row */
+    Int row ;			/* a row index */
+    Int col ;			/* a column index */
+    Int max_score ;		/* maximum possible score */
+    Int cur_score ;		/* score of current column */
+    UInt hash ;		/* hash value for supernode detection */
+    Int head_column ;		/* head of hash bucket */
+    Int first_col ;		/* first column in hash bucket */
+    Int tag_mark ;		/* marker value for mark array */
+    Int row_mark ;		/* Row [row].shared2.mark */
+    Int set_difference ;	/* set difference size of row with pivot row */
+    Int min_score ;		/* smallest column score */
+    Int col_thickness ;		/* "thickness" (no. of columns in a supercol) */
+    Int max_mark ;		/* maximum value of tag_mark */
+    Int pivot_col_thickness ;	/* number of columns represented by pivot col */
+    Int prev_col ;		/* Used by Dlist operations. */
+    Int next_col ;		/* Used by Dlist operations. */
+    Int ngarbage ;		/* number of garbage collections performed */
+
+#ifndef NDEBUG
+    Int debug_d ;		/* debug loop counter */
+    Int debug_step = 0 ;	/* debug loop counter */
+#endif /* NDEBUG */
+
+    /* === Initialization and clear mark ==================================== */
+
+    max_mark = INT_MAX - n_col ;	/* INT_MAX defined in <limits.h> */
+    tag_mark = clear_mark (0, max_mark, n_row, Row) ;
+    min_score = 0 ;
+    ngarbage = 0 ;
+    DEBUG1 (("colamd: Ordering, n_col2=%d\n", n_col2)) ;
+
+    /* === Order the columns ================================================ */
+
+    for (k = 0 ; k < n_col2 ; /* 'k' is incremented below */)
+    {
+
+#ifndef NDEBUG
+	if (debug_step % 100 == 0)
+	{
+	    DEBUG2 (("\n...       Step k: %d out of n_col2: %d\n", k, n_col2)) ;
+	}
+	else
+	{
+	    DEBUG3 (("\n----------Step k: %d out of n_col2: %d\n", k, n_col2)) ;
+	}
+	debug_step++ ;
+	debug_deg_lists (n_row, n_col, Row, Col, head,
+		min_score, n_col2-k, max_deg) ;
+	debug_matrix (n_row, n_col, Row, Col, A) ;
+#endif /* NDEBUG */
+
+	/* === Select pivot column, and order it ============================ */
+
+	/* make sure degree list isn't empty */
+	ASSERT (min_score >= 0) ;
+	ASSERT (min_score <= n_col) ;
+	ASSERT (head [min_score] >= EMPTY) ;
+
+#ifndef NDEBUG
+	for (debug_d = 0 ; debug_d < min_score ; debug_d++)
+	{
+	    ASSERT (head [debug_d] == EMPTY) ;
+	}
+#endif /* NDEBUG */
+
+	/* get pivot column from head of minimum degree list */
+	while (head [min_score] == EMPTY && min_score < n_col)
+	{
+	    min_score++ ;
+	}
+	pivot_col = head [min_score] ;
+	ASSERT (pivot_col >= 0 && pivot_col <= n_col) ;
+	next_col = Col [pivot_col].shared4.degree_next ;
+	head [min_score] = next_col ;
+	if (next_col != EMPTY)
+	{
+	    Col [next_col].shared3.prev = EMPTY ;
+	}
+
+	ASSERT (COL_IS_ALIVE (pivot_col)) ;
+
+	/* remember score for defrag check */
+	pivot_col_score = Col [pivot_col].shared2.score ;
+
+	/* the pivot column is the kth column in the pivot order */
+	Col [pivot_col].shared2.order = k ;
+
+	/* increment order count by column thickness */
+	pivot_col_thickness = Col [pivot_col].shared1.thickness ;
+	k += pivot_col_thickness ;
+	ASSERT (pivot_col_thickness > 0) ;
+	DEBUG3 (("Pivot col: %d thick %d\n", pivot_col, pivot_col_thickness)) ;
+
+	/* === Garbage_collection, if necessary ============================= */
+
+	needed_memory = MIN (pivot_col_score, n_col - k) ;
+	if (pfree + needed_memory >= Alen)
+	{
+	    pfree = garbage_collection (n_row, n_col, Row, Col, A, &A [pfree]) ;
+	    ngarbage++ ;
+	    /* after garbage collection we will have enough */
+	    ASSERT (pfree + needed_memory < Alen) ;
+	    /* garbage collection has wiped out the Row[].shared2.mark array */
+	    tag_mark = clear_mark (0, max_mark, n_row, Row) ;
+
+#ifndef NDEBUG
+	    debug_matrix (n_row, n_col, Row, Col, A) ;
+#endif /* NDEBUG */
+	}
+
+	/* === Compute pivot row pattern ==================================== */
+
+	/* get starting location for this new merged row */
+	pivot_row_start = pfree ;
+
+	/* initialize new row counts to zero */
+	pivot_row_degree = 0 ;
+
+	/* tag pivot column as having been visited so it isn't included */
+	/* in merged pivot row */
+	Col [pivot_col].shared1.thickness = -pivot_col_thickness ;
+
+	/* pivot row is the union of all rows in the pivot column pattern */
+	cp = &A [Col [pivot_col].start] ;
+	cp_end = cp + Col [pivot_col].length ;
+	while (cp < cp_end)
+	{
+	    /* get a row */
+	    row = *cp++ ;
+	    DEBUG4 (("Pivot col pattern %d %d\n", ROW_IS_ALIVE (row), row)) ;
+	    /* skip if row is dead */
+	    if (ROW_IS_ALIVE (row))
+	    {
+		rp = &A [Row [row].start] ;
+		rp_end = rp + Row [row].length ;
+		while (rp < rp_end)
+		{
+		    /* get a column */
+		    col = *rp++ ;
+		    /* add the column, if alive and untagged */
+		    col_thickness = Col [col].shared1.thickness ;
+		    if (col_thickness > 0 && COL_IS_ALIVE (col))
+		    {
+			/* tag column in pivot row */
+			Col [col].shared1.thickness = -col_thickness ;
+			ASSERT (pfree < Alen) ;
+			/* place column in pivot row */
+			A [pfree++] = col ;
+			pivot_row_degree += col_thickness ;
+		    }
+		}
+	    }
+	}
+
+	/* clear tag on pivot column */
+	Col [pivot_col].shared1.thickness = pivot_col_thickness ;
+	max_deg = MAX (max_deg, pivot_row_degree) ;
+
+#ifndef NDEBUG
+	DEBUG3 (("check2\n")) ;
+	debug_mark (n_row, Row, tag_mark, max_mark) ;
+#endif /* NDEBUG */
+
+	/* === Kill all rows used to construct pivot row ==================== */
+
+	/* also kill pivot row, temporarily */
+	cp = &A [Col [pivot_col].start] ;
+	cp_end = cp + Col [pivot_col].length ;
+	while (cp < cp_end)
+	{
+	    /* may be killing an already dead row */
+	    row = *cp++ ;
+	    DEBUG3 (("Kill row in pivot col: %d\n", row)) ;
+	    KILL_ROW (row) ;
+	}
+
+	/* === Select a row index to use as the new pivot row =============== */
+
+	pivot_row_length = pfree - pivot_row_start ;
+	if (pivot_row_length > 0)
+	{
+	    /* pick the "pivot" row arbitrarily (first row in col) */
+	    pivot_row = A [Col [pivot_col].start] ;
+	    DEBUG3 (("Pivotal row is %d\n", pivot_row)) ;
+	}
+	else
+	{
+	    /* there is no pivot row, since it is of zero length */
+	    pivot_row = EMPTY ;
+	    ASSERT (pivot_row_length == 0) ;
+	}
+	ASSERT (Col [pivot_col].length > 0 || pivot_row_length == 0) ;
+
+	/* === Approximate degree computation =============================== */
+
+	/* Here begins the computation of the approximate degree.  The column */
+	/* score is the sum of the pivot row "length", plus the size of the */
+	/* set differences of each row in the column minus the pattern of the */
+	/* pivot row itself.  The column ("thickness") itself is also */
+	/* excluded from the column score (we thus use an approximate */
+	/* external degree). */
+
+	/* The time taken by the following code (compute set differences, and */
+	/* add them up) is proportional to the size of the data structure */
+	/* being scanned - that is, the sum of the sizes of each column in */
+	/* the pivot row.  Thus, the amortized time to compute a column score */
+	/* is proportional to the size of that column (where size, in this */
+	/* context, is the column "length", or the number of row indices */
+	/* in that column).  The number of row indices in a column is */
+	/* monotonically non-decreasing, from the length of the original */
+	/* column on input to colamd. */
+
+	/* === Compute set differences ====================================== */
+
+	DEBUG3 (("** Computing set differences phase. **\n")) ;
+
+	/* pivot row is currently dead - it will be revived later. */
+
+	DEBUG3 (("Pivot row: ")) ;
+	/* for each column in pivot row */
+	rp = &A [pivot_row_start] ;
+	rp_end = rp + pivot_row_length ;
+	while (rp < rp_end)
+	{
+	    col = *rp++ ;
+	    ASSERT (COL_IS_ALIVE (col) && col != pivot_col) ;
+	    DEBUG3 (("Col: %d\n", col)) ;
+
+	    /* clear tags used to construct pivot row pattern */
+	    col_thickness = -Col [col].shared1.thickness ;
+	    ASSERT (col_thickness > 0) ;
+	    Col [col].shared1.thickness = col_thickness ;
+
+	    /* === Remove column from degree list =========================== */
+
+	    cur_score = Col [col].shared2.score ;
+	    prev_col = Col [col].shared3.prev ;
+	    next_col = Col [col].shared4.degree_next ;
+	    ASSERT (cur_score >= 0) ;
+	    ASSERT (cur_score <= n_col) ;
+	    ASSERT (cur_score >= EMPTY) ;
+	    if (prev_col == EMPTY)
+	    {
+		head [cur_score] = next_col ;
+	    }
+	    else
+	    {
+		Col [prev_col].shared4.degree_next = next_col ;
+	    }
+	    if (next_col != EMPTY)
+	    {
+		Col [next_col].shared3.prev = prev_col ;
+	    }
+
+	    /* === Scan the column ========================================== */
+
+	    cp = &A [Col [col].start] ;
+	    cp_end = cp + Col [col].length ;
+	    while (cp < cp_end)
+	    {
+		/* get a row */
+		row = *cp++ ;
+		row_mark = Row [row].shared2.mark ;
+		/* skip if dead */
+		if (ROW_IS_MARKED_DEAD (row_mark))
+		{
+		    continue ;
+		}
+		ASSERT (row != pivot_row) ;
+		set_difference = row_mark - tag_mark ;
+		/* check if the row has been seen yet */
+		if (set_difference < 0)
+		{
+		    ASSERT (Row [row].shared1.degree <= max_deg) ;
+		    set_difference = Row [row].shared1.degree ;
+		}
+		/* subtract column thickness from this row's set difference */
+		set_difference -= col_thickness ;
+		ASSERT (set_difference >= 0) ;
+		/* absorb this row if the set difference becomes zero */
+		if (set_difference == 0 && aggressive)
+		{
+		    DEBUG3 (("aggressive absorption. Row: %d\n", row)) ;
+		    KILL_ROW (row) ;
+		}
+		else
+		{
+		    /* save the new mark */
+		    Row [row].shared2.mark = set_difference + tag_mark ;
+		}
+	    }
+	}
+
+#ifndef NDEBUG
+	debug_deg_lists (n_row, n_col, Row, Col, head,
+		min_score, n_col2-k-pivot_row_degree, max_deg) ;
+#endif /* NDEBUG */
+
+	/* === Add up set differences for each column ======================= */
+
+	DEBUG3 (("** Adding set differences phase. **\n")) ;
+
+	/* for each column in pivot row */
+	rp = &A [pivot_row_start] ;
+	rp_end = rp + pivot_row_length ;
+	while (rp < rp_end)
+	{
+	    /* get a column */
+	    col = *rp++ ;
+	    ASSERT (COL_IS_ALIVE (col) && col != pivot_col) ;
+	    hash = 0 ;
+	    cur_score = 0 ;
+	    cp = &A [Col [col].start] ;
+	    /* compact the column */
+	    new_cp = cp ;
+	    cp_end = cp + Col [col].length ;
+
+	    DEBUG4 (("Adding set diffs for Col: %d.\n", col)) ;
+
+	    while (cp < cp_end)
+	    {
+		/* get a row */
+		row = *cp++ ;
+		ASSERT(row >= 0 && row < n_row) ;
+		row_mark = Row [row].shared2.mark ;
+		/* skip if dead */
+		if (ROW_IS_MARKED_DEAD (row_mark))
+		{
+		    DEBUG4 ((" Row %d, dead\n", row)) ;
+		    continue ;
+		}
+		DEBUG4 ((" Row %d, set diff %d\n", row, row_mark-tag_mark));
+		ASSERT (row_mark >= tag_mark) ;
+		/* compact the column */
+		*new_cp++ = row ;
+		/* compute hash function */
+		hash += row ;
+		/* add set difference */
+		cur_score += row_mark - tag_mark ;
+		/* integer overflow... */
+		cur_score = MIN (cur_score, n_col) ;
+	    }
+
+	    /* recompute the column's length */
+	    Col [col].length = (Int) (new_cp - &A [Col [col].start]) ;
+
+	    /* === Further mass elimination ================================= */
+
+	    if (Col [col].length == 0)
+	    {
+		DEBUG4 (("further mass elimination. Col: %d\n", col)) ;
+		/* nothing left but the pivot row in this column */
+		KILL_PRINCIPAL_COL (col) ;
+		pivot_row_degree -= Col [col].shared1.thickness ;
+		ASSERT (pivot_row_degree >= 0) ;
+		/* order it */
+		Col [col].shared2.order = k ;
+		/* increment order count by column thickness */
+		k += Col [col].shared1.thickness ;
+	    }
+	    else
+	    {
+		/* === Prepare for supercolumn detection ==================== */
+
+		DEBUG4 (("Preparing supercol detection for Col: %d.\n", col)) ;
+
+		/* save score so far */
+		Col [col].shared2.score = cur_score ;
+
+		/* add column to hash table, for supercolumn detection */
+		hash %= n_col + 1 ;
+
+		DEBUG4 ((" Hash = %d, n_col = %d.\n", hash, n_col)) ;
+		ASSERT (((Int) hash) <= n_col) ;
+
+		head_column = head [hash] ;
+		if (head_column > EMPTY)
+		{
+		    /* degree list "hash" is non-empty, use prev (shared3) of */
+		    /* first column in degree list as head of hash bucket */
+		    first_col = Col [head_column].shared3.headhash ;
+		    Col [head_column].shared3.headhash = col ;
+		}
+		else
+		{
+		    /* degree list "hash" is empty, use head as hash bucket */
+		    first_col = - (head_column + 2) ;
+		    head [hash] = - (col + 2) ;
+		}
+		Col [col].shared4.hash_next = first_col ;
+
+		/* save hash function in Col [col].shared3.hash */
+		Col [col].shared3.hash = (Int) hash ;
+		ASSERT (COL_IS_ALIVE (col)) ;
+	    }
+	}
+
+	/* The approximate external column degree is now computed.  */
+
+	/* === Supercolumn detection ======================================== */
+
+	DEBUG3 (("** Supercolumn detection phase. **\n")) ;
+
+	detect_super_cols (
+
+#ifndef NDEBUG
+		n_col, Row,
+#endif /* NDEBUG */
+
+		Col, A, head, pivot_row_start, pivot_row_length) ;
+
+	/* === Kill the pivotal column ====================================== */
+
+	KILL_PRINCIPAL_COL (pivot_col) ;
+
+	/* === Clear mark =================================================== */
+
+	tag_mark = clear_mark (tag_mark+max_deg+1, max_mark, n_row, Row) ;
+
+#ifndef NDEBUG
+	DEBUG3 (("check3\n")) ;
+	debug_mark (n_row, Row, tag_mark, max_mark) ;
+#endif /* NDEBUG */
+
+	/* === Finalize the new pivot row, and column scores ================ */
+
+	DEBUG3 (("** Finalize scores phase. **\n")) ;
+
+	/* for each column in pivot row */
+	rp = &A [pivot_row_start] ;
+	/* compact the pivot row */
+	new_rp = rp ;
+	rp_end = rp + pivot_row_length ;
+	while (rp < rp_end)
+	{
+	    col = *rp++ ;
+	    /* skip dead columns */
+	    if (COL_IS_DEAD (col))
+	    {
+		continue ;
+	    }
+	    *new_rp++ = col ;
+	    /* add new pivot row to column */
+	    A [Col [col].start + (Col [col].length++)] = pivot_row ;
+
+	    /* retrieve score so far and add on pivot row's degree. */
+	    /* (we wait until here for this in case the pivot */
+	    /* row's degree was reduced due to mass elimination). */
+	    cur_score = Col [col].shared2.score + pivot_row_degree ;
+
+	    /* calculate the max possible score as the number of */
+	    /* external columns minus the 'k' value minus the */
+	    /* columns thickness */
+	    max_score = n_col - k - Col [col].shared1.thickness ;
+
+	    /* make the score the external degree of the union-of-rows */
+	    cur_score -= Col [col].shared1.thickness ;
+
+	    /* make sure score is less or equal than the max score */
+	    cur_score = MIN (cur_score, max_score) ;
+	    ASSERT (cur_score >= 0) ;
+
+	    /* store updated score */
+	    Col [col].shared2.score = cur_score ;
+
+	    /* === Place column back in degree list ========================= */
+
+	    ASSERT (min_score >= 0) ;
+	    ASSERT (min_score <= n_col) ;
+	    ASSERT (cur_score >= 0) ;
+	    ASSERT (cur_score <= n_col) ;
+	    ASSERT (head [cur_score] >= EMPTY) ;
+	    next_col = head [cur_score] ;
+	    Col [col].shared4.degree_next = next_col ;
+	    Col [col].shared3.prev = EMPTY ;
+	    if (next_col != EMPTY)
+	    {
+		Col [next_col].shared3.prev = col ;
+	    }
+	    head [cur_score] = col ;
+
+	    /* see if this score is less than current min */
+	    min_score = MIN (min_score, cur_score) ;
+
+	}
+
+#ifndef NDEBUG
+	debug_deg_lists (n_row, n_col, Row, Col, head,
+		min_score, n_col2-k, max_deg) ;
+#endif /* NDEBUG */
+
+	/* === Resurrect the new pivot row ================================== */
+
+	if (pivot_row_degree > 0)
+	{
+	    /* update pivot row length to reflect any cols that were killed */
+	    /* during super-col detection and mass elimination */
+	    Row [pivot_row].start  = pivot_row_start ;
+	    Row [pivot_row].length = (Int) (new_rp - &A[pivot_row_start]) ;
+	    ASSERT (Row [pivot_row].length > 0) ;
+	    Row [pivot_row].shared1.degree = pivot_row_degree ;
+	    Row [pivot_row].shared2.mark = 0 ;
+	    /* pivot row is no longer dead */
+
+	    DEBUG1 (("Resurrect Pivot_row %d deg: %d\n",
+			pivot_row, pivot_row_degree)) ;
+	}
+    }
+
+    /* === All principal columns have now been ordered ====================== */
+
+    return (ngarbage) ;
+}
+
+
+/* ========================================================================== */
+/* === order_children ======================================================= */
+/* ========================================================================== */
+
+/*
+    The find_ordering routine has ordered all of the principal columns (the
+    representatives of the supercolumns).  The non-principal columns have not
+    yet been ordered.  This routine orders those columns by walking up the
+    parent tree (a column is a child of the column which absorbed it).  The
+    final permutation vector is then placed in p [0 ... n_col-1], with p [0]
+    being the first column, and p [n_col-1] being the last.  It doesn't look
+    like it at first glance, but be assured that this routine takes time linear
+    in the number of columns.  Although not immediately obvious, the time
+    taken by this routine is O (n_col), that is, linear in the number of
+    columns.  Not user-callable.
+*/
+
+PRIVATE void order_children
+(
+    /* === Parameters ======================================================= */
+
+    Int n_col,			/* number of columns of A */
+    Colamd_Col Col [],		/* of size n_col+1 */
+    Int p []			/* p [0 ... n_col-1] is the column permutation*/
+)
+{
+    /* === Local variables ================================================== */
+
+    Int i ;			/* loop counter for all columns */
+    Int c ;			/* column index */
+    Int parent ;		/* index of column's parent */
+    Int order ;			/* column's order */
+
+    /* === Order each non-principal column ================================== */
+
+    for (i = 0 ; i < n_col ; i++)
+    {
+	/* find an un-ordered non-principal column */
+	ASSERT (COL_IS_DEAD (i)) ;
+	if (!COL_IS_DEAD_PRINCIPAL (i) && Col [i].shared2.order == EMPTY)
+	{
+	    parent = i ;
+	    /* once found, find its principal parent */
+	    do
+	    {
+		parent = Col [parent].shared1.parent ;
+	    } while (!COL_IS_DEAD_PRINCIPAL (parent)) ;
+
+	    /* now, order all un-ordered non-principal columns along path */
+	    /* to this parent.  collapse tree at the same time */
+	    c = i ;
+	    /* get order of parent */
+	    order = Col [parent].shared2.order ;
+
+	    do
+	    {
+		ASSERT (Col [c].shared2.order == EMPTY) ;
+
+		/* order this column */
+		Col [c].shared2.order = order++ ;
+		/* collaps tree */
+		Col [c].shared1.parent = parent ;
+
+		/* get immediate parent of this column */
+		c = Col [c].shared1.parent ;
+
+		/* continue until we hit an ordered column.  There are */
+		/* guarranteed not to be anymore unordered columns */
+		/* above an ordered column */
+	    } while (Col [c].shared2.order == EMPTY) ;
+
+	    /* re-order the super_col parent to largest order for this group */
+	    Col [parent].shared2.order = order ;
+	}
+    }
+
+    /* === Generate the permutation ========================================= */
+
+    for (c = 0 ; c < n_col ; c++)
+    {
+	p [Col [c].shared2.order] = c ;
+    }
+}
+
+
+/* ========================================================================== */
+/* === detect_super_cols ==================================================== */
+/* ========================================================================== */
+
+/*
+    Detects supercolumns by finding matches between columns in the hash buckets.
+    Check amongst columns in the set A [row_start ... row_start + row_length-1].
+    The columns under consideration are currently *not* in the degree lists,
+    and have already been placed in the hash buckets.
+
+    The hash bucket for columns whose hash function is equal to h is stored
+    as follows:
+
+	if head [h] is >= 0, then head [h] contains a degree list, so:
+
+		head [h] is the first column in degree bucket h.
+		Col [head [h]].headhash gives the first column in hash bucket h.
+
+	otherwise, the degree list is empty, and:
+
+		-(head [h] + 2) is the first column in hash bucket h.
+
+    For a column c in a hash bucket, Col [c].shared3.prev is NOT a "previous
+    column" pointer.  Col [c].shared3.hash is used instead as the hash number
+    for that column.  The value of Col [c].shared4.hash_next is the next column
+    in the same hash bucket.
+
+    Assuming no, or "few" hash collisions, the time taken by this routine is
+    linear in the sum of the sizes (lengths) of each column whose score has
+    just been computed in the approximate degree computation.
+    Not user-callable.
+*/
+
+PRIVATE void detect_super_cols
+(
+    /* === Parameters ======================================================= */
+
+#ifndef NDEBUG
+    /* these two parameters are only needed when debugging is enabled: */
+    Int n_col,			/* number of columns of A */
+    Colamd_Row Row [],		/* of size n_row+1 */
+#endif /* NDEBUG */
+
+    Colamd_Col Col [],		/* of size n_col+1 */
+    Int A [],			/* row indices of A */
+    Int head [],		/* head of degree lists and hash buckets */
+    Int row_start,		/* pointer to set of columns to check */
+    Int row_length		/* number of columns to check */
+)
+{
+    /* === Local variables ================================================== */
+
+    Int hash ;			/* hash value for a column */
+    Int *rp ;			/* pointer to a row */
+    Int c ;			/* a column index */
+    Int super_c ;		/* column index of the column to absorb into */
+    Int *cp1 ;			/* column pointer for column super_c */
+    Int *cp2 ;			/* column pointer for column c */
+    Int length ;		/* length of column super_c */
+    Int prev_c ;		/* column preceding c in hash bucket */
+    Int i ;			/* loop counter */
+    Int *rp_end ;		/* pointer to the end of the row */
+    Int col ;			/* a column index in the row to check */
+    Int head_column ;		/* first column in hash bucket or degree list */
+    Int first_col ;		/* first column in hash bucket */
+
+    /* === Consider each column in the row ================================== */
+
+    rp = &A [row_start] ;
+    rp_end = rp + row_length ;
+    while (rp < rp_end)
+    {
+	col = *rp++ ;
+	if (COL_IS_DEAD (col))
+	{
+	    continue ;
+	}
+
+	/* get hash number for this column */
+	hash = Col [col].shared3.hash ;
+	ASSERT (hash <= n_col) ;
+
+	/* === Get the first column in this hash bucket ===================== */
+
+	head_column = head [hash] ;
+	if (head_column > EMPTY)
+	{
+	    first_col = Col [head_column].shared3.headhash ;
+	}
+	else
+	{
+	    first_col = - (head_column + 2) ;
+	}
+
+	/* === Consider each column in the hash bucket ====================== */
+
+	for (super_c = first_col ; super_c != EMPTY ;
+	    super_c = Col [super_c].shared4.hash_next)
+	{
+	    ASSERT (COL_IS_ALIVE (super_c)) ;
+	    ASSERT (Col [super_c].shared3.hash == hash) ;
+	    length = Col [super_c].length ;
+
+	    /* prev_c is the column preceding column c in the hash bucket */
+	    prev_c = super_c ;
+
+	    /* === Compare super_c with all columns after it ================ */
+
+	    for (c = Col [super_c].shared4.hash_next ;
+		 c != EMPTY ; c = Col [c].shared4.hash_next)
+	    {
+		ASSERT (c != super_c) ;
+		ASSERT (COL_IS_ALIVE (c)) ;
+		ASSERT (Col [c].shared3.hash == hash) ;
+
+		/* not identical if lengths or scores are different */
+		if (Col [c].length != length ||
+		    Col [c].shared2.score != Col [super_c].shared2.score)
+		{
+		    prev_c = c ;
+		    continue ;
+		}
+
+		/* compare the two columns */
+		cp1 = &A [Col [super_c].start] ;
+		cp2 = &A [Col [c].start] ;
+
+		for (i = 0 ; i < length ; i++)
+		{
+		    /* the columns are "clean" (no dead rows) */
+		    ASSERT (ROW_IS_ALIVE (*cp1))  ;
+		    ASSERT (ROW_IS_ALIVE (*cp2))  ;
+		    /* row indices will same order for both supercols, */
+		    /* no gather scatter nessasary */
+		    if (*cp1++ != *cp2++)
+		    {
+			break ;
+		    }
+		}
+
+		/* the two columns are different if the for-loop "broke" */
+		if (i != length)
+		{
+		    prev_c = c ;
+		    continue ;
+		}
+
+		/* === Got it!  two columns are identical =================== */
+
+		ASSERT (Col [c].shared2.score == Col [super_c].shared2.score) ;
+
+		Col [super_c].shared1.thickness += Col [c].shared1.thickness ;
+		Col [c].shared1.parent = super_c ;
+		KILL_NON_PRINCIPAL_COL (c) ;
+		/* order c later, in order_children() */
+		Col [c].shared2.order = EMPTY ;
+		/* remove c from hash bucket */
+		Col [prev_c].shared4.hash_next = Col [c].shared4.hash_next ;
+	    }
+	}
+
+	/* === Empty this hash bucket ======================================= */
+
+	if (head_column > EMPTY)
+	{
+	    /* corresponding degree list "hash" is not empty */
+	    Col [head_column].shared3.headhash = EMPTY ;
+	}
+	else
+	{
+	    /* corresponding degree list "hash" is empty */
+	    head [hash] = EMPTY ;
+	}
+    }
+}
+
+
+/* ========================================================================== */
+/* === garbage_collection =================================================== */
+/* ========================================================================== */
+
+/*
+    Defragments and compacts columns and rows in the workspace A.  Used when
+    all avaliable memory has been used while performing row merging.  Returns
+    the index of the first free position in A, after garbage collection.  The
+    time taken by this routine is linear is the size of the array A, which is
+    itself linear in the number of nonzeros in the input matrix.
+    Not user-callable.
+*/
+
+PRIVATE Int garbage_collection  /* returns the new value of pfree */
+(
+    /* === Parameters ======================================================= */
+
+    Int n_row,			/* number of rows */
+    Int n_col,			/* number of columns */
+    Colamd_Row Row [],		/* row info */
+    Colamd_Col Col [],		/* column info */
+    Int A [],			/* A [0 ... Alen-1] holds the matrix */
+    Int *pfree			/* &A [0] ... pfree is in use */
+)
+{
+    /* === Local variables ================================================== */
+
+    Int *psrc ;			/* source pointer */
+    Int *pdest ;		/* destination pointer */
+    Int j ;			/* counter */
+    Int r ;			/* a row index */
+    Int c ;			/* a column index */
+    Int length ;		/* length of a row or column */
+
+#ifndef NDEBUG
+    Int debug_rows ;
+    DEBUG2 (("Defrag..\n")) ;
+    for (psrc = &A[0] ; psrc < pfree ; psrc++) ASSERT (*psrc >= 0) ;
+    debug_rows = 0 ;
+#endif /* NDEBUG */
+
+    /* === Defragment the columns =========================================== */
+
+    pdest = &A[0] ;
+    for (c = 0 ; c < n_col ; c++)
+    {
+	if (COL_IS_ALIVE (c))
+	{
+	    psrc = &A [Col [c].start] ;
+
+	    /* move and compact the column */
+	    ASSERT (pdest <= psrc) ;
+	    Col [c].start = (Int) (pdest - &A [0]) ;
+	    length = Col [c].length ;
+	    for (j = 0 ; j < length ; j++)
+	    {
+		r = *psrc++ ;
+		if (ROW_IS_ALIVE (r))
+		{
+		    *pdest++ = r ;
+		}
+	    }
+	    Col [c].length = (Int) (pdest - &A [Col [c].start]) ;
+	}
+    }
+
+    /* === Prepare to defragment the rows =================================== */
+
+    for (r = 0 ; r < n_row ; r++)
+    {
+	if (ROW_IS_DEAD (r) || (Row [r].length == 0))
+	{
+	    /* This row is already dead, or is of zero length.  Cannot compact
+	     * a row of zero length, so kill it.  NOTE: in the current version,
+	     * there are no zero-length live rows.  Kill the row (for the first
+	     * time, or again) just to be safe. */
+	    KILL_ROW (r) ;
+	}
+	else
+	{
+	    /* save first column index in Row [r].shared2.first_column */
+	    psrc = &A [Row [r].start] ;
+	    Row [r].shared2.first_column = *psrc ;
+	    ASSERT (ROW_IS_ALIVE (r)) ;
+	    /* flag the start of the row with the one's complement of row */
+	    *psrc = ONES_COMPLEMENT (r) ;
+#ifndef NDEBUG
+	    debug_rows++ ;
+#endif /* NDEBUG */
+	}
+    }
+
+    /* === Defragment the rows ============================================== */
+
+    psrc = pdest ;
+    while (psrc < pfree)
+    {
+	/* find a negative number ... the start of a row */
+	if (*psrc++ < 0)
+	{
+	    psrc-- ;
+	    /* get the row index */
+	    r = ONES_COMPLEMENT (*psrc) ;
+	    ASSERT (r >= 0 && r < n_row) ;
+	    /* restore first column index */
+	    *psrc = Row [r].shared2.first_column ;
+	    ASSERT (ROW_IS_ALIVE (r)) ;
+	    ASSERT (Row [r].length > 0) ;
+	    /* move and compact the row */
+	    ASSERT (pdest <= psrc) ;
+	    Row [r].start = (Int) (pdest - &A [0]) ;
+	    length = Row [r].length ;
+	    for (j = 0 ; j < length ; j++)
+	    {
+		c = *psrc++ ;
+		if (COL_IS_ALIVE (c))
+		{
+		    *pdest++ = c ;
+		}
+	    }
+	    Row [r].length = (Int) (pdest - &A [Row [r].start]) ;
+	    ASSERT (Row [r].length > 0) ;
+#ifndef NDEBUG
+	    debug_rows-- ;
+#endif /* NDEBUG */
+	}
+    }
+    /* ensure we found all the rows */
+    ASSERT (debug_rows == 0) ;
+
+    /* === Return the new value of pfree ==================================== */
+
+    return ((Int) (pdest - &A [0])) ;
+}
+
+
+/* ========================================================================== */
+/* === clear_mark =========================================================== */
+/* ========================================================================== */
+
+/*
+    Clears the Row [].shared2.mark array, and returns the new tag_mark.
+    Return value is the new tag_mark.  Not user-callable.
+*/
+
+PRIVATE Int clear_mark	/* return the new value for tag_mark */
+(
+    /* === Parameters ======================================================= */
+
+    Int tag_mark,	/* new value of tag_mark */
+    Int max_mark,	/* max allowed value of tag_mark */
+
+    Int n_row,		/* number of rows in A */
+    Colamd_Row Row []	/* Row [0 ... n_row-1].shared2.mark is set to zero */
+)
+{
+    /* === Local variables ================================================== */
+
+    Int r ;
+
+    if (tag_mark <= 0 || tag_mark >= max_mark)
+    {
+	for (r = 0 ; r < n_row ; r++)
+	{
+	    if (ROW_IS_ALIVE (r))
+	    {
+		Row [r].shared2.mark = 0 ;
+	    }
+	}
+	tag_mark = 1 ;
+    }
+
+    return (tag_mark) ;
+}
+
+
+/* ========================================================================== */
+/* === print_report ========================================================= */
+/* ========================================================================== */
+
+PRIVATE void print_report
+(
+    char *method,
+    Int stats [COLAMD_STATS]
+)
+{
+
+    Int i1, i2, i3 ;
+
+    SUITESPARSE_PRINTF (("\n%s version %d.%d.%d, %s: ", method,
+            COLAMD_MAIN_VERSION, COLAMD_SUB_VERSION, COLAMD_SUBSUB_VERSION, 
+            COLAMD_DATE)) ;
+
+    if (!stats)
+    {
+        SUITESPARSE_PRINTF (("No statistics available.\n")) ;
+	return ;
+    }
+
+    i1 = stats [COLAMD_INFO1] ;
+    i2 = stats [COLAMD_INFO2] ;
+    i3 = stats [COLAMD_INFO3] ;
+
+    if (stats [COLAMD_STATUS] >= 0)
+    {
+        SUITESPARSE_PRINTF (("OK.  ")) ;
+    }
+    else
+    {
+        SUITESPARSE_PRINTF (("ERROR.  ")) ;
+    }
+
+    switch (stats [COLAMD_STATUS])
+    {
+
+	case COLAMD_OK_BUT_JUMBLED:
+
+            SUITESPARSE_PRINTF((
+                    "Matrix has unsorted or duplicate row indices.\n")) ;
+
+            SUITESPARSE_PRINTF((
+                    "%s: number of duplicate or out-of-order row indices: %d\n",
+                    method, i3)) ;
+
+            SUITESPARSE_PRINTF((
+                    "%s: last seen duplicate or out-of-order row index:   %d\n",
+                    method, INDEX (i2))) ;
+
+            SUITESPARSE_PRINTF((
+                    "%s: last seen in column:                             %d",
+                    method, INDEX (i1))) ;
+
+	    /* no break - fall through to next case instead */
+
+	case COLAMD_OK:
+
+            SUITESPARSE_PRINTF(("\n")) ;
+
+            SUITESPARSE_PRINTF((
+                    "%s: number of dense or empty rows ignored:           %d\n",
+                    method, stats [COLAMD_DENSE_ROW])) ;
+
+            SUITESPARSE_PRINTF((
+                    "%s: number of dense or empty columns ignored:        %d\n",
+                    method, stats [COLAMD_DENSE_COL])) ;
+
+            SUITESPARSE_PRINTF((
+                    "%s: number of garbage collections performed:         %d\n",
+                    method, stats [COLAMD_DEFRAG_COUNT])) ;
+	    break ;
+
+	case COLAMD_ERROR_A_not_present:
+
+	    SUITESPARSE_PRINTF((
+                    "Array A (row indices of matrix) not present.\n")) ;
+	    break ;
+
+	case COLAMD_ERROR_p_not_present:
+
+            SUITESPARSE_PRINTF((
+                    "Array p (column pointers for matrix) not present.\n")) ;
+	    break ;
+
+	case COLAMD_ERROR_nrow_negative:
+
+            SUITESPARSE_PRINTF(("Invalid number of rows (%d).\n", i1)) ;
+	    break ;
+
+	case COLAMD_ERROR_ncol_negative:
+
+            SUITESPARSE_PRINTF(("Invalid number of columns (%d).\n", i1)) ;
+	    break ;
+
+	case COLAMD_ERROR_nnz_negative:
+
+            SUITESPARSE_PRINTF((
+                    "Invalid number of nonzero entries (%d).\n", i1)) ;
+	    break ;
+
+	case COLAMD_ERROR_p0_nonzero:
+
+            SUITESPARSE_PRINTF((
+                    "Invalid column pointer, p [0] = %d, must be zero.\n", i1));
+	    break ;
+
+	case COLAMD_ERROR_A_too_small:
+
+            SUITESPARSE_PRINTF(("Array A too small.\n")) ;
+            SUITESPARSE_PRINTF((
+                    "        Need Alen >= %d, but given only Alen = %d.\n",
+                    i1, i2)) ;
+	    break ;
+
+	case COLAMD_ERROR_col_length_negative:
+
+            SUITESPARSE_PRINTF
+            (("Column %d has a negative number of nonzero entries (%d).\n",
+            INDEX (i1), i2)) ;
+	    break ;
+
+	case COLAMD_ERROR_row_index_out_of_bounds:
+
+            SUITESPARSE_PRINTF
+            (("Row index (row %d) out of bounds (%d to %d) in column %d.\n",
+            INDEX (i2), INDEX (0), INDEX (i3-1), INDEX (i1))) ;
+	    break ;
+
+	case COLAMD_ERROR_out_of_memory:
+
+            SUITESPARSE_PRINTF(("Out of memory.\n")) ;
+	    break ;
+
+	/* v2.4: internal-error case deleted */
+    }
+}
+
+
+
+
+/* ========================================================================== */
+/* === colamd debugging routines ============================================ */
+/* ========================================================================== */
+
+/* When debugging is disabled, the remainder of this file is ignored. */
+
+#ifndef NDEBUG
+
+
+/* ========================================================================== */
+/* === debug_structures ===================================================== */
+/* ========================================================================== */
+
+/*
+    At this point, all empty rows and columns are dead.  All live columns
+    are "clean" (containing no dead rows) and simplicial (no supercolumns
+    yet).  Rows may contain dead columns, but all live rows contain at
+    least one live column.
+*/
+
+PRIVATE void debug_structures
+(
+    /* === Parameters ======================================================= */
+
+    Int n_row,
+    Int n_col,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int A [],
+    Int n_col2
+)
+{
+    /* === Local variables ================================================== */
+
+    Int i ;
+    Int c ;
+    Int *cp ;
+    Int *cp_end ;
+    Int len ;
+    Int score ;
+    Int r ;
+    Int *rp ;
+    Int *rp_end ;
+    Int deg ;
+
+    /* === Check A, Row, and Col ============================================ */
+
+    for (c = 0 ; c < n_col ; c++)
+    {
+	if (COL_IS_ALIVE (c))
+	{
+	    len = Col [c].length ;
+	    score = Col [c].shared2.score ;
+	    DEBUG4 (("initial live col %5d %5d %5d\n", c, len, score)) ;
+	    ASSERT (len > 0) ;
+	    ASSERT (score >= 0) ;
+	    ASSERT (Col [c].shared1.thickness == 1) ;
+	    cp = &A [Col [c].start] ;
+	    cp_end = cp + len ;
+	    while (cp < cp_end)
+	    {
+		r = *cp++ ;
+		ASSERT (ROW_IS_ALIVE (r)) ;
+	    }
+	}
+	else
+	{
+	    i = Col [c].shared2.order ;
+	    ASSERT (i >= n_col2 && i < n_col) ;
+	}
+    }
+
+    for (r = 0 ; r < n_row ; r++)
+    {
+	if (ROW_IS_ALIVE (r))
+	{
+	    i = 0 ;
+	    len = Row [r].length ;
+	    deg = Row [r].shared1.degree ;
+	    ASSERT (len > 0) ;
+	    ASSERT (deg > 0) ;
+	    rp = &A [Row [r].start] ;
+	    rp_end = rp + len ;
+	    while (rp < rp_end)
+	    {
+		c = *rp++ ;
+		if (COL_IS_ALIVE (c))
+		{
+		    i++ ;
+		}
+	    }
+	    ASSERT (i > 0) ;
+	}
+    }
+}
+
+
+/* ========================================================================== */
+/* === debug_deg_lists ====================================================== */
+/* ========================================================================== */
+
+/*
+    Prints the contents of the degree lists.  Counts the number of columns
+    in the degree list and compares it to the total it should have.  Also
+    checks the row degrees.
+*/
+
+PRIVATE void debug_deg_lists
+(
+    /* === Parameters ======================================================= */
+
+    Int n_row,
+    Int n_col,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int head [],
+    Int min_score,
+    Int should,
+    Int max_deg
+)
+{
+    /* === Local variables ================================================== */
+
+    Int deg ;
+    Int col ;
+    Int have ;
+    Int row ;
+
+    /* === Check the degree lists =========================================== */
+
+    if (n_col > 10000 && colamd_debug <= 0)
+    {
+	return ;
+    }
+    have = 0 ;
+    DEBUG4 (("Degree lists: %d\n", min_score)) ;
+    for (deg = 0 ; deg <= n_col ; deg++)
+    {
+	col = head [deg] ;
+	if (col == EMPTY)
+	{
+	    continue ;
+	}
+	DEBUG4 (("%d:", deg)) ;
+	while (col != EMPTY)
+	{
+	    DEBUG4 ((" %d", col)) ;
+	    have += Col [col].shared1.thickness ;
+	    ASSERT (COL_IS_ALIVE (col)) ;
+	    col = Col [col].shared4.degree_next ;
+	}
+	DEBUG4 (("\n")) ;
+    }
+    DEBUG4 (("should %d have %d\n", should, have)) ;
+    ASSERT (should == have) ;
+
+    /* === Check the row degrees ============================================ */
+
+    if (n_row > 10000 && colamd_debug <= 0)
+    {
+	return ;
+    }
+    for (row = 0 ; row < n_row ; row++)
+    {
+	if (ROW_IS_ALIVE (row))
+	{
+	    ASSERT (Row [row].shared1.degree <= max_deg) ;
+	}
+    }
+}
+
+
+/* ========================================================================== */
+/* === debug_mark =========================================================== */
+/* ========================================================================== */
+
+/*
+    Ensures that the tag_mark is less that the maximum and also ensures that
+    each entry in the mark array is less than the tag mark.
+*/
+
+PRIVATE void debug_mark
+(
+    /* === Parameters ======================================================= */
+
+    Int n_row,
+    Colamd_Row Row [],
+    Int tag_mark,
+    Int max_mark
+)
+{
+    /* === Local variables ================================================== */
+
+    Int r ;
+
+    /* === Check the Row marks ============================================== */
+
+    ASSERT (tag_mark > 0 && tag_mark <= max_mark) ;
+    if (n_row > 10000 && colamd_debug <= 0)
+    {
+	return ;
+    }
+    for (r = 0 ; r < n_row ; r++)
+    {
+	ASSERT (Row [r].shared2.mark < tag_mark) ;
+    }
+}
+
+
+/* ========================================================================== */
+/* === debug_matrix ========================================================= */
+/* ========================================================================== */
+
+/*
+    Prints out the contents of the columns and the rows.
+*/
+
+PRIVATE void debug_matrix
+(
+    /* === Parameters ======================================================= */
+
+    Int n_row,
+    Int n_col,
+    Colamd_Row Row [],
+    Colamd_Col Col [],
+    Int A []
+)
+{
+    /* === Local variables ================================================== */
+
+    Int r ;
+    Int c ;
+    Int *rp ;
+    Int *rp_end ;
+    Int *cp ;
+    Int *cp_end ;
+
+    /* === Dump the rows and columns of the matrix ========================== */
+
+    if (colamd_debug < 3)
+    {
+	return ;
+    }
+    DEBUG3 (("DUMP MATRIX:\n")) ;
+    for (r = 0 ; r < n_row ; r++)
+    {
+	DEBUG3 (("Row %d alive? %d\n", r, ROW_IS_ALIVE (r))) ;
+	if (ROW_IS_DEAD (r))
+	{
+	    continue ;
+	}
+	DEBUG3 (("start %d length %d degree %d\n",
+		Row [r].start, Row [r].length, Row [r].shared1.degree)) ;
+	rp = &A [Row [r].start] ;
+	rp_end = rp + Row [r].length ;
+	while (rp < rp_end)
+	{
+	    c = *rp++ ;
+	    DEBUG4 (("	%d col %d\n", COL_IS_ALIVE (c), c)) ;
+	}
+    }
+
+    for (c = 0 ; c < n_col ; c++)
+    {
+	DEBUG3 (("Col %d alive? %d\n", c, COL_IS_ALIVE (c))) ;
+	if (COL_IS_DEAD (c))
+	{
+	    continue ;
+	}
+	DEBUG3 (("start %d length %d shared1 %d shared2 %d\n",
+		Col [c].start, Col [c].length,
+		Col [c].shared1.thickness, Col [c].shared2.score)) ;
+	cp = &A [Col [c].start] ;
+	cp_end = cp + Col [c].length ;
+	while (cp < cp_end)
+	{
+	    r = *cp++ ;
+	    DEBUG4 (("	%d row %d\n", ROW_IS_ALIVE (r), r)) ;
+	}
+    }
+}
+
+PRIVATE void colamd_get_debug
+(
+    char *method
+)
+{
+    FILE *f ;
+    colamd_debug = 0 ;		/* no debug printing */
+    f = fopen ("debug", "r") ;
+    if (f == (FILE *) NULL)
+    {
+	colamd_debug = 0 ;
+    }
+    else
+    {
+	fscanf (f, "%d", &colamd_debug) ;
+	fclose (f) ;
+    }
+    DEBUG0 (("%s: debug version, D = %d (THIS WILL BE SLOW!)\n",
+    	method, colamd_debug)) ;
+}
+
+#endif /* NDEBUG */
diff --git a/colamd/colamd.h b/colamd/colamd.h
new file mode 100644
index 0000000..afcb6f5
--- /dev/null
+++ b/colamd/colamd.h
@@ -0,0 +1,236 @@
+//------------------------------------------------------------------------------
+// COLAMD/Source/colamd.h: include file for COLAMD
+//------------------------------------------------------------------------------
+
+// COLAMD, Copyright (c) 1998-2022, Timothy A. Davis and Stefan Larimore,
+// All Rights Reserved.
+// SPDX-License-Identifier: BSD-3-clause
+
+//------------------------------------------------------------------------------
+
+/* COLAMD / SYMAMD include file
+
+    You must include this file (colamd.h) in any routine that uses colamd,
+    symamd, or the related macros and definitions.
+
+    Authors:
+
+        The authors of the code itself are Stefan I. Larimore and Timothy A.
+        Davis (DrTimothyAldenDavis@gmail.com).  The algorithm was
+        developed in collaboration with John Gilbert, Xerox PARC, and Esmond
+        Ng, Oak Ridge National Laboratory.
+
+    Acknowledgements:
+
+        This work was supported by the National Science Foundation, under
+        grants DMS-9504974 and DMS-9803599.
+
+    Availability:
+
+        The colamd/symamd library is available at http://www.suitesparse.com
+        This file is required by the colamd.c, colamdmex.c, and symamdmex.c
+        files, and by any C code that calls the routines whose prototypes are
+        listed below, or that uses the colamd/symamd definitions listed below.
+
+*/
+
+#ifndef COLAMD_H
+#define COLAMD_H
+
+/* make it easy for C++ programs to include COLAMD */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* ========================================================================== */
+/* === Include files ======================================================== */
+/* ========================================================================== */
+
+#include "SuiteSparse_config.h"
+
+/* ========================================================================== */
+/* === COLAMD version ======================================================= */
+/* ========================================================================== */
+
+/* COLAMD Version 2.4 and later will include the following definitions.
+ * As an example, to test if the version you are using is 2.4 or later:
+ *
+ * #ifdef COLAMD_VERSION
+ *     if (COLAMD_VERSION >= COLAMD_VERSION_CODE (2,4)) ...
+ * #endif
+ *
+ * This also works during compile-time:
+ *
+ *  #if defined(COLAMD_VERSION) && (COLAMD_VERSION >= COLAMD_VERSION_CODE (2,4))
+ *    printf ("This is version 2.4 or later\n") ;
+ *  #else
+ *    printf ("This is an early version\n") ;
+ *  #endif
+ *
+ * Versions 2.3 and earlier of COLAMD do not include a #define'd version number.
+ */
+
+#define COLAMD_DATE "June 16, 2023"
+#define COLAMD_MAIN_VERSION   3
+#define COLAMD_SUB_VERSION    0
+#define COLAMD_SUBSUB_VERSION 4
+
+#define COLAMD_VERSION_CODE(main,sub) ((main) * 1000 + (sub))
+#define COLAMD_VERSION \
+        COLAMD_VERSION_CODE(COLAMD_MAIN_VERSION,COLAMD_SUB_VERSION)
+
+/* ========================================================================== */
+/* === Knob and statistics definitions ====================================== */
+/* ========================================================================== */
+
+/* size of the knobs [ ] array.  Only knobs [0..1] are currently used. */
+#define COLAMD_KNOBS 20
+
+/* number of output statistics.  Only stats [0..6] are currently used. */
+#define COLAMD_STATS 20
+
+/* knobs [0] and stats [0]: dense row knob and output statistic. */
+#define COLAMD_DENSE_ROW 0
+
+/* knobs [1] and stats [1]: dense column knob and output statistic. */
+#define COLAMD_DENSE_COL 1
+
+/* knobs [2]: aggressive absorption */
+#define COLAMD_AGGRESSIVE 2
+
+/* stats [2]: memory defragmentation count output statistic */
+#define COLAMD_DEFRAG_COUNT 2
+
+/* stats [3]: colamd status:  zero OK, > 0 warning or notice, < 0 error */
+#define COLAMD_STATUS 3
+
+/* stats [4..6]: error info, or info on jumbled columns */ 
+#define COLAMD_INFO1 4
+#define COLAMD_INFO2 5
+#define COLAMD_INFO3 6
+
+/* error codes returned in stats [3]: */
+#define COLAMD_OK                               (0)
+#define COLAMD_OK_BUT_JUMBLED                   (1)
+#define COLAMD_ERROR_A_not_present              (-1)
+#define COLAMD_ERROR_p_not_present              (-2)
+#define COLAMD_ERROR_nrow_negative              (-3)
+#define COLAMD_ERROR_ncol_negative              (-4)
+#define COLAMD_ERROR_nnz_negative               (-5)
+#define COLAMD_ERROR_p0_nonzero                 (-6)
+#define COLAMD_ERROR_A_too_small                (-7)
+#define COLAMD_ERROR_col_length_negative        (-8)
+#define COLAMD_ERROR_row_index_out_of_bounds    (-9)
+#define COLAMD_ERROR_out_of_memory              (-10)
+#define COLAMD_ERROR_internal_error             (-999)
+
+
+/* ========================================================================== */
+/* === Prototypes of user-callable routines ================================= */
+/* ========================================================================== */
+
+size_t colamd_recommended       /* returns recommended value of Alen, */
+                                /* or 0 if input arguments are erroneous */
+(
+    int32_t nnz,                /* nonzeros in A */
+    int32_t n_row,              /* number of rows in A */
+    int32_t n_col               /* number of columns in A */
+) ;
+
+size_t colamd_l_recommended     /* returns recommended value of Alen, */
+                                /* or 0 if input arguments are erroneous */
+(
+    int64_t nnz,                /* nonzeros in A */
+    int64_t n_row,              /* number of rows in A */
+    int64_t n_col               /* number of columns in A */
+) ;
+
+void colamd_set_defaults        /* sets default parameters */
+(                               /* knobs argument is modified on output */
+    double knobs [COLAMD_KNOBS] /* parameter settings for colamd */
+) ;
+
+void colamd_l_set_defaults      /* sets default parameters */
+(                               /* knobs argument is modified on output */
+    double knobs [COLAMD_KNOBS] /* parameter settings for colamd */
+) ;
+
+int colamd                      /* returns (1) if successful, (0) otherwise*/
+(                               /* A and p arguments are modified on output */
+    int32_t n_row,              /* number of rows in A */
+    int32_t n_col,              /* number of columns in A */
+    int32_t Alen,               /* size of the array A */
+    int32_t A [],               /* row indices of A, of size Alen */
+    int32_t p [],               /* column pointers of A, of size n_col+1 */
+    double knobs [COLAMD_KNOBS],    /* parameter settings for colamd */
+    int32_t stats [COLAMD_STATS]    /* colamd output stats and error codes */
+) ;
+
+int colamd_l                    /* returns (1) if successful, (0) otherwise*/
+(                               /* A and p arguments are modified on output */
+    int64_t n_row,              /* number of rows in A */
+    int64_t n_col,              /* number of columns in A */
+    int64_t Alen,               /* size of the array A */
+    int64_t A [],               /* row indices of A, of size Alen */
+    int64_t p [],               /* column pointers of A, of size n_col+1 */
+    double knobs [COLAMD_KNOBS],    /* parameter settings for colamd */
+    int64_t stats [COLAMD_STATS]    /* colamd output stats and error codes */
+) ;
+
+int symamd                              /* return (1) if OK, (0) otherwise */
+(
+    int32_t n,                          /* number of rows and columns of A */
+    int32_t A [],                       /* row indices of A */
+    int32_t p [],                       /* column pointers of A */
+    int32_t perm [],                    /* output permutation, size n_col+1 */
+    double knobs [COLAMD_KNOBS],        /* parameters (uses defaults if NULL) */
+    int32_t stats [COLAMD_STATS],       /* output stats and error codes */
+    void * (*allocate) (size_t, size_t),
+                                        /* pointer to calloc (ANSI C) or */
+                                        /* mxCalloc (for MATLAB mexFunction) */
+    void (*release) (void *)
+                                        /* pointer to free (ANSI C) or */
+                                        /* mxFree (for MATLAB mexFunction) */
+) ;
+
+int symamd_l                            /* return (1) if OK, (0) otherwise */
+(
+    int64_t n,                          /* number of rows and columns of A */
+    int64_t A [],                       /* row indices of A */
+    int64_t p [],                       /* column pointers of A */
+    int64_t perm [],                    /* output permutation, size n_col+1 */
+    double knobs [COLAMD_KNOBS],        /* parameters (uses defaults if NULL) */
+    int64_t stats [COLAMD_STATS],       /* output stats and error codes */
+    void * (*allocate) (size_t, size_t),
+                                        /* pointer to calloc (ANSI C) or */
+                                        /* mxCalloc (for MATLAB mexFunction) */
+    void (*release) (void *)
+                                        /* pointer to free (ANSI C) or */
+                                        /* mxFree (for MATLAB mexFunction) */
+) ;
+
+void colamd_report
+(
+    int32_t stats [COLAMD_STATS]
+) ;
+
+void colamd_l_report
+(
+    int64_t stats [COLAMD_STATS]
+) ;
+
+void symamd_report
+(
+    int32_t stats [COLAMD_STATS]
+) ;
+
+void symamd_l_report
+(
+    int64_t stats [COLAMD_STATS]
+) ;
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* COLAMD_H */
-- 
2.41.0