update packages

[CreaPhase.git] / octave_packages / m / sparse / colperm.m

diff --git a/octave_packages/m/sparse/colperm.m b/octave_packages/m/sparse/colperm.m
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+++ b/octave_packages/m/sparse/colperm.m
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+## Copyright (C) 2004-2012 David Bateman and Andy Adler
+##
+## This file is part of Octave.
+##
+## Octave is free software; you can redistribute it and/or modify it
+## under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 3 of the License, or (at
+## your option) any later version.
+##
+## Octave is distributed in the hope that it will be useful, but
+## WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+## General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{p} =} colperm (@var{s})
+## Return the column permutations such that the columns of
+## @code{@var{s} (:, @var{p})} are ordered in terms of increase number
+## of non-zero elements.  If @var{s} is symmetric, then @var{p} is chosen
+## such that @code{@var{s} (@var{p}, @var{p})} orders the rows and
+## columns with increasing number of non zeros elements.
+## @end deftypefn
+
+function p = colperm (s)
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  [i, j] = find (s);
+  idx = find (diff ([j; Inf]) != 0);
+  [dummy, p] = sort (idx - [0; idx(1:(end-1))]);
+endfunction