Mercurial > octave
view scripts/linear-algebra/bandwidth.m @ 27919:1891570abac8
update Octave Project Developers copyright for the new year
In files that have the "Octave Project Developers" copyright notice,
update for 2020.
author | John W. Eaton <jwe@octave.org> |
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date | Mon, 06 Jan 2020 22:29:51 -0500 |
parents | b442ec6dda5c |
children | bd51beb6205e |
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## Copyright (C) 2014-2020 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this distribution ## or <https://octave.org/COPYRIGHT.html/>. ## ## ## 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 ## <https://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {} {@var{bw} =} bandwidth (@var{A}, @var{type}) ## @deftypefnx {} {[@var{lower}, @var{upper}] =} bandwidth (@var{A}) ## Compute the bandwidth of @var{A}. ## ## The @var{type} argument is the string @qcode{"lower"} for the lower ## bandwidth and @qcode{"upper"} for the upper bandwidth. If no @var{type} is ## specified return both the lower and upper bandwidth of @var{A}. ## ## The lower/upper bandwidth of a matrix is the number of ## subdiagonals/superdiagonals with nonzero entries. ## ## @seealso{isbanded, isdiag, istril, istriu} ## @end deftypefn ## Author: Massimiliano Fasi function [lower, upper] = bandwidth (A, type) if (! ((nargin == 1 && nargout == 2) || (nargin == 2 && nargout <= 1))) print_usage (); endif if (! isnumeric (A) && ! islogical (A) || ndims (A) != 2) error ("bandwidth: A must be a 2-D numeric or logical matrix"); elseif (nargin == 2 && ! (strcmp (type, "lower") || strcmp (type, "upper"))) error ('bandwidth: TYPE must be "lower" or "upper"'); endif if (nargin == 1) [i, j] = find (A); if (isempty (i)) lower = upper = 0; else lower = max (i - j); upper = max (j - i); endif else [i, j] = find (A); if (isempty (i)) lower = 0; elseif (strcmp (type, "lower")) lower = max (i - j); else lower = max (j - i); endif endif endfunction %!test %! [a,b] = bandwidth (speye (100)); %! assert ([a,b] == [0,0]); %! assert (bandwidth (speye (100), "upper"), 0); %! assert (bandwidth (speye (100), "lower"), 0); %!test %! A = [2 3 0 0 0; 1 2 3 0 0; 0 1 2 3 0; 0 0 1 2 3; 0 0 0 1 2]; %! [a,b] = bandwidth (A); %! assert ([a,b] == [1,1]); %! assert (bandwidth (A, "lower"), 1); %! assert (bandwidth (A, "upper"), 1); %!assert (bandwidth ([], "lower"), 0) %!assert (bandwidth ([], "upper"), 0) %!assert (bandwidth (zeros (3,3), "lower"), 0) %!assert (bandwidth (zeros (3,3), "upper"), 0) %!assert (bandwidth (ones (5,5), "lower"), 4) %!assert (bandwidth (ones (5,5), "upper"), 4) %!test %! [a,b] = bandwidth ([]); %! assert ([a,b] == [0,0]); %!test %! [a,b] = bandwidth (zeros (3,3)); %! assert ([a,b] == [0,0]); %!test %! [a,b] = bandwidth (ones (5,5)); %! assert ([a,b] == [4,4]); ## Test input validation %!error bandwidth () %!error bandwidth (1,2,3) %!error [a,b,c] = bandwidth (ones (2)) %!error [a,b] = bandwidth (ones (2), "upper") %!error <A must be a 2-D numeric or logical> bandwidth ("string", "lower") %!error <A must be a 2-D numeric or logical> bandwidth (ones (3,3,3), "lower") %!error <TYPE must be "lower" or "upper"> bandwidth (ones (2), "uper") %!error <TYPE must be "lower" or "upper"> bandwidth (ones (2), "uppper")