Mercurial > octave-nkf
view scripts/linear-algebra/trace.m @ 20618:e5986cba4ca8
new octave_value::cell_value method with optional error message
* ov.h, ov.cc (octave_value::cell_value): New method.
* ov-base.h, ov-base.cc (octave_base_value::cell_value):
New default method.
* ov-cell.h, ov-cell.cc (octave_cell::cell_value): New method.
author | John W. Eaton <jwe@octave.org> |
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date | Fri, 09 Oct 2015 14:41:49 -0400 |
parents | 4197fc428c7d |
children |
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## Copyright (C) 1993-2015 John W. Eaton ## ## 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} {} trace (@var{A}) ## Compute the trace of @var{A}, the sum of the elements along the main ## diagonal. ## ## The implementation is straightforward: @code{sum (diag (@var{A}))}. ## @seealso{eig} ## @end deftypefn ## Author: jwe function y = trace (A) if (nargin != 1) print_usage (); endif if (ndims (A) > 2) error ("trace: only valid on 2-D objects"); elseif (isempty (A)) y = 0; elseif (isvector (A)) y = A(1); else y = sum (diag (A)); endif endfunction %!assert (trace ([1, 2; 3, 4]), 5) %!assert (trace ([1, 2; 3, 4; 5, 6]), 5) %!assert (trace ([1, 3, 5; 2, 4, 6]), 5) %!assert (trace ([]), 0) %!assert (trace (rand (1,0)), 0) %!assert (trace ([3:10]), 3) %!error trace () %!error trace (1, 2) %!error <only valid on 2-D objects> trace (reshape (1:9,[1,3,3]))