Mercurial > hg > octave-nkf
view scripts/sparse/spalloc.m @ 5563:a75de3db5c37
[project @ 2005-12-06 16:29:48 by jwe]
author | jwe |
---|---|
date | Tue, 06 Dec 2005 16:29:49 +0000 |
parents | 4c8a2e4e0717 |
children | 2618a0750ae6 |
line wrap: on
line source
## Copyright (C) 2004 David Bateman & Andy Adler ## ## This program 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 2 of the License, or ## (at your option) any later version. ## ## This program 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 this program; if not, write to the Free Software ## Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA ## 02110-1301 USA ## -*- texinfo -*- ## @deftypefn {Function File} {@var{s} =} spalloc (@var{r}, @var{c}, @var{nz}) ## Returns an empty sparse matrix of size @var{r}-by-@var{c}. As Octave ## resizes sparse matrices at the first opportunity, so that no additional ## space is needed, the argument @var{nz} is ignored. This function is ## provided only for compatiability reasons. ## ## It should be noted that this means that code like ## ## @example ## k = 5; ## nz = r * k; ## s = spalloc (r, c, nz) ## for j = 1:c ## idx = randperm (r); ## s (:, j) = [zeros(r - k, 1); rand(k, 1)] (idx); ## endfor ## @end example ## ## will reallocate memory at each step. It is therefore vitally important ## that code like this is vectorized as much as possible. ## @end deftypefn ## @seealso{sparse, nzmax} function s = spalloc (r, c, nz) s = sparse (r, c); endfunction