Mercurial > octave-libgccjit
diff scripts/linear-algebra/issymmetric.m @ 9869:ecd750d1eabd
move issymmetric & isdefinite to linear-algebra, create ishermitian
author | Jaroslav Hajek <highegg@gmail.com> |
---|---|
date | Tue, 24 Nov 2009 15:02:04 +0100 |
parents | scripts/general/issymmetric.m@eb63fbe60fab |
children | 73fc43e01f4c |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/scripts/linear-algebra/issymmetric.m Tue Nov 24 15:02:04 2009 +0100 @@ -0,0 +1,68 @@ +## Copyright (C) 1996, 1997, 2002, 2003, 2004, 2005, 2006, 2007, 2008 +## John W. Eaton +## Copyright (C) 2009 VZLU Prague +## +## 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} {} issymmetric (@var{x}, @var{tol}) +## Return true if @var{x} is a symmetric matrix within the tolerance specified +## by @var{tol}, otherwise return false. The default tolerance is zero (uses +## faster code). +## Matrix @var{x} is considered symmetric if +## @code{norm (@var{x} - @var{x}.', inf) / norm (@var{x}, inf) < @var{tol}}. +## @seealso{size, rows, columns, length, ismatrix, isscalar, +## issquare, isvector} +## @end deftypefn + +## Author: A. S. Hodel <scotte@eng.auburn.edu> +## Created: August 1993 +## Adapted-By: jwe + +function retval = issymmetric (x, tol = 0) + + if (nargin < 1 || nargin > 2) + print_usage (); + endif + + retval = issquare (x); + if (retval) + if (tol == 0) + retval = all ((x == x.')(:)); + else + norm_x = norm (x, inf); + retval = norm_x == 0 || norm (x - x.', inf) / norm_x <= tol; + endif + endif + +endfunction + +%!assert(issymmetric (1)); +%!assert(!(issymmetric ([1, 2]))); +%!assert(issymmetric ([])); +%!assert(issymmetric ([1, 2; 2, 1])); +%!assert(!(issymmetric ("test"))); +%!assert(issymmetric ([1, 2.1; 2, 1.1], 0.2)); +%!assert(issymmetric ([1, 2i; 2i, 1])); +%!assert(!(issymmetric ("t"))); +%!assert(!(issymmetric (["te"; "et"]))); +%!error issymmetric ([1, 2; 2, 1], 0, 0); +%!error issymmetric (); + +%!test +%! s.a = 1; +%! assert(!(issymmetric (s)));