Mercurial > octave-antonio
view scripts/sparse/spdiags.m @ 20164:df437a52bcaf stable
doc: Update more docstrings to have one sentence summary as first line.
Reviewed miscellaneous, sparse, strings in scripts directory.
* scripts/miscellaneous/bzip2.m, scripts/miscellaneous/citation.m,
scripts/miscellaneous/compare_versions.m, scripts/miscellaneous/computer.m,
scripts/miscellaneous/debug.m, scripts/miscellaneous/dir.m,
scripts/miscellaneous/edit.m, scripts/miscellaneous/error_ids.m,
scripts/miscellaneous/fileattrib.m, scripts/miscellaneous/fullfile.m,
scripts/miscellaneous/genvarname.m, scripts/miscellaneous/gzip.m,
scripts/miscellaneous/mkoctfile.m, scripts/miscellaneous/news.m,
scripts/miscellaneous/open.m, scripts/miscellaneous/parseparams.m,
scripts/miscellaneous/recycle.m, scripts/miscellaneous/run.m,
scripts/miscellaneous/swapbytes.m, scripts/miscellaneous/tar.m,
scripts/miscellaneous/tmpnam.m, scripts/miscellaneous/unpack.m,
scripts/miscellaneous/what.m, scripts/sparse/bicg.m, scripts/sparse/bicgstab.m,
scripts/sparse/cgs.m, scripts/sparse/colperm.m, scripts/sparse/eigs.m,
scripts/sparse/etreeplot.m, scripts/sparse/gmres.m, scripts/sparse/gplot.m,
scripts/sparse/ichol.m, scripts/sparse/ilu.m, scripts/sparse/pcg.m,
scripts/sparse/pcr.m, scripts/sparse/qmr.m, scripts/sparse/spaugment.m,
scripts/sparse/spconvert.m, scripts/sparse/spdiags.m, scripts/sparse/spfun.m,
scripts/sparse/spones.m, scripts/sparse/sprandsym.m, scripts/sparse/spstats.m,
scripts/sparse/spy.m, scripts/sparse/svds.m, scripts/sparse/treelayout.m,
scripts/sparse/treeplot.m, scripts/strings/base2dec.m,
scripts/strings/bin2dec.m, scripts/strings/blanks.m, scripts/strings/cstrcat.m,
scripts/strings/deblank.m, scripts/strings/dec2base.m,
scripts/strings/dec2bin.m, scripts/strings/dec2hex.m,
scripts/strings/findstr.m, scripts/strings/hex2dec.m, scripts/strings/index.m,
scripts/strings/isletter.m, scripts/strings/isstrprop.m,
scripts/strings/mat2str.m, scripts/strings/ostrsplit.m,
scripts/strings/regexptranslate.m, scripts/strings/rindex.m,
scripts/strings/str2num.m, scripts/strings/strcat.m, scripts/strings/strchr.m,
scripts/strings/strjoin.m, scripts/strings/strjust.m,
scripts/strings/strmatch.m, scripts/strings/strsplit.m,
scripts/strings/strtok.m, scripts/strings/strtrim.m,
scripts/strings/strtrunc.m, scripts/strings/substr.m,
scripts/strings/untabify.m, scripts/time/datenum.m:
Update more docstrings to have one sentence summary as first line.
author | Rik <rik@octave.org> |
---|---|
date | Mon, 04 May 2015 14:22:02 -0700 |
parents | 9fc020886ae9 |
children |
line wrap: on
line source
## Copyright (C) 2000-2015 Paul Kienzle ## ## 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{B} =} spdiags (@var{A}) ## @deftypefnx {Function File} {[@var{B}, @var{d}] =} spdiags (@var{A}) ## @deftypefnx {Function File} {@var{B} =} spdiags (@var{A}, @var{d}) ## @deftypefnx {Function File} {@var{A} =} spdiags (@var{v}, @var{d}, @var{A}) ## @deftypefnx {Function File} {@var{A} =} spdiags (@var{v}, @var{d}, @var{m}, @var{n}) ## A generalization of the function @code{diag}. ## ## Called with a single input argument, the nonzero diagonals @var{d} of ## @var{A} are extracted. ## ## With two arguments the diagonals to extract are given by the vector @var{d}. ## ## The other two forms of @code{spdiags} modify the input matrix by replacing ## the diagonals. They use the columns of @var{v} to replace the diagonals ## represented by the vector @var{d}. If the sparse matrix @var{A} is ## defined then the diagonals of this matrix are replaced. Otherwise a ## matrix of @var{m} by @var{n} is created with the diagonals given by the ## columns of @var{v}. ## ## Negative values of @var{d} represent diagonals below the main diagonal, and ## positive values of @var{d} diagonals above the main diagonal. ## ## For example: ## ## @example ## @group ## spdiags (reshape (1:12, 4, 3), [-1 0 1], 5, 4) ## @result{} 5 10 0 0 ## 1 6 11 0 ## 0 2 7 12 ## 0 0 3 8 ## 0 0 0 4 ## @end group ## @end example ## ## @seealso{diag} ## @end deftypefn function [B, d] = spdiags (v, d, m, n) if (nargin < 1 || nargin > 4) print_usage (); endif if (nargin == 1 || nargin == 2) ## extract nonzero diagonals of A into B,d [nr, nc] = size (v); [i, j] = find (v); if (nargin == 1) ## d contains the active diagonals d = unique (j-i); endif ## FIXME: Maybe this could be done faster using [i,j,v] = find (v) ## and then massaging the indices i, j. However, some ## benchmarking has shown that diag() written in C++ makes ## the following code faster even with the for loop. Brows = min (nr, nc); B = zeros (Brows, length (d)); for k = 1:length (d) dn = d(k); if (dn <= -nr || dn > nc) continue; endif dv = diag (v, dn); len = rows (dv); ## Put sub/super-diagonals in the right place based on matrix size (MxN) if (nr >= nc) if (dn > 0) offset = Brows - len + 1; B(offset:Brows, k) = dv; else B(1:len, k) = dv; endif else if (dn < 0) offset = Brows - len + 1; B(offset:Brows, k) = dv; else B(1:len, k) = dv; endif endif endfor elseif (nargin == 3) ## Replace specific diagonals d of m with v,d [nr, nc] = size (m); A = spdiags (m, d); B = m - spdiags (A, d, nr, nc) + spdiags (v, d, nr, nc); else ## Create new matrix of size mxn using v,d [j, i, v] = find (v); if (m >= n) offset = max (min (d(:), n-m), 0); else offset = d(:); endif j = j(:) + offset(i(:)); i = j - d(:)(i(:)); idx = i > 0 & i <= m & j > 0 & j <= n; B = sparse (i(idx), j(idx), v(idx), m, n); endif endfunction %!test %! [B,d] = spdiags (magic (3)); %! assert (d, [-2 -1 0 1 2]'); %! assert (B, [4 3 8 0 0 %! 0 9 5 1 0 %! 0 0 2 7 6]); %! B = spdiags (magic (3), [-2 1]); %! assert (B, [4 0; 0 1; 0 7]); ## Test zero filling for supra- and super-diagonals %!test %! ## Case 1: M = N %! A = sparse (zeros (3,3)); %! A(1,3) = 13; %! A(3,1) = 31; %! [B, d] = spdiags (A); %! assert (d, [-2 2]'); %! assert (B, [31 0; 0 0; 0 13]); %! assert (spdiags (B, d, 3,3), A) %!test %! ## Case 1: M > N %! A = sparse (zeros (4,3)); %! A(1,3) = 13; %! A(3,1) = 31; %! [B, d] = spdiags (A); %! assert (d, [-2 2]'); %! assert (B, [31 0; 0 0; 0 13]); %! assert (spdiags (B, d, 4,3), A) %!test %! ## Case 1: M < N %! A = sparse (zeros (3,4)); %! A(1,3) = 13; %! A(3,1) = 31; %! [B, d] = spdiags (A); %! assert (d, [-2 2]'); %! assert (B, [0 13; 0 0; 31 0]); %! assert (spdiags (B, d, 3,4), A) %!assert (spdiags (zeros (1,0),1,1,1), sparse (0)) %!assert (spdiags (zeros (0,1),1,1,1), sparse (0)) %!assert (spdiags ([0.5 -1 0.5], 0:2, 1, 1), sparse (0.5)) ## Test input validation %!error spdiags () %!error spdiags (1,2,3,4,5)