--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/liboctave/COLAMD/colamd.m	Fri Feb 25 19:55:28 2005 +0000
@@ -0,0 +1,109 @@
+function [p,stats] = colamd (S, knobs)
+%COLAMD Column approximate minimum degree permutation.
+%    P = COLAMD (S) returns the column approximate minimum degree permutation
+%    vector for the sparse matrix S.  For a non-symmetric matrix S, S (:,P)
+%    tends to have sparser LU factors than S.  The Cholesky factorization of
+%    S (:,P)' * S (:,P) also tends to be sparser than that of S'*S.  COLAMD
+%    tends to be faster than COLMMD and tends to return a better ordering.
+%
+%    See also COLMMD, COLPERM, SPPARMS, SYMAMD, SYMMMD, SYMRCM.
+%
+%    Usage:  P = colamd (S)
+%            P = colamd (S, knobs)
+%            [P, stats] = colamd (S)
+%            [P, stats] = colamd (S, knobs)
+%
+%    knobs is an optional two-element input vector.  If S is m-by-n, then
+%    rows with more than (knobs (1))*n entries are ignored.  Columns with
+%    more than (knobs (2))*m entries are removed prior to ordering, and
+%    ordered last in the output permutation P.  If the knobs parameter is not
+%    present, then 0.5 is used instead, for both knobs (1) and knobs (2). 
+%    knobs (3) controls the printing of statistics and error messages.
+%
+%    stats is an optional 20-element output vector that provides data about the
+%    ordering and the validity of the input matrix S.  Ordering statistics are
+%    in stats (1:3).  stats (1) and stats (2) are the number of dense or empty
+%    rows and columns ignored by COLAMD and stats (3) is the number of
+%    garbage collections performed on the internal data structure used by
+%    COLAMD (roughly of size 2.2*nnz(S) + 4*m + 7*n integers).
+%
+%    MATLAB built-in functions are intended to generate valid sparse matrices,
+%    with no duplicate entries, with ascending row indices of the nonzeros
+%    in each column, with a non-negative number of entries in each column (!)
+%    and so on.  If a matrix is invalid, then COLAMD may or may not be able
+%    to continue.  If there are duplicate entries (a row index appears two or
+%    more times in the same column) or if the row indices in a column are out
+%    of order, then COLAMD can correct these errors by ignoring the duplicate
+%    entries and sorting each column of its internal copy of the matrix S (the
+%    input matrix S is not repaired, however).  If a matrix is invalid in other
+%    ways then COLAMD cannot continue, an error message is printed, and no
+%    output arguments (P or stats) are returned.  COLAMD is thus a simple way
+%    to check a sparse matrix to see if it's valid.
+%
+%    stats (4:7) provide information if COLAMD was able to continue.  The
+%    matrix is OK if stats (4) is zero, or 1 if invalid.  stats (5) is the
+%    rightmost column index that is unsorted or contains duplicate entries,
+%    or zero if no such column exists.  stats (6) is the last seen duplicate
+%    or out-of-order row index in the column index given by stats (5), or zero
+%    if no such row index exists.  stats (7) is the number of duplicate or
+%    out-of-order row indices.
+%
+%    stats (8:20) is always zero in the current version of COLAMD (reserved
+%    for future use).
+%
+%    The ordering is followed by a column elimination tree post-ordering.
+%
+%    Authors:
+%
+%	The authors of the code itself are Stefan I. Larimore and Timothy A.
+%	Davis (davis@cise.ufl.edu), University of Florida.  The algorithm was
+%	developed in collaboration with John Gilbert, Xerox PARC, and Esmond
+%	Ng, Oak Ridge National Laboratory.
+%
+%    Date:
+%
+%	September 8, 2003.  Version 2.3.
+%
+%    Acknowledgements:
+%
+%	This work was supported by the National Science Foundation, under
+%	grants DMS-9504974 and DMS-9803599.
+
+%    Notice:
+%
+%	Copyright (c) 1998-2003 by the University of Florida.
+%	All Rights Reserved.
+%
+%	See http://www.cise.ufl.edu/research/sparse/colamd (the colamd.c
+%	file) for the License.
+%
+%    Availability:
+%
+%	The colamd/symamd library is available at
+%
+%	    http://www.cise.ufl.edu/research/sparse/colamd/
+%
+
+%-------------------------------------------------------------------------------
+% Perform the colamd ordering:
+%-------------------------------------------------------------------------------
+
+if (nargout <= 1 & nargin == 1)
+    p = colamdmex (S) ;
+elseif (nargout <= 1 & nargin == 2)
+    p = colamdmex (S, knobs) ;
+elseif (nargout == 2 & nargin == 1)
+    [p, stats] = colamdmex (S) ;
+elseif (nargout == 2 & nargin == 2)
+    [p, stats] = colamdmex (S, knobs) ;
+else
+    error ('colamd:  incorrect number of input and/or output arguments') ;
+end
+
+%-------------------------------------------------------------------------------
+% column elimination tree post-ordering:
+%-------------------------------------------------------------------------------
+
+[ignore, q] = sparsfun ('coletree', S (:,p)) ;
+p = p (q) ;
+