Mercurial > octave
view scripts/linear-algebra/trace.m @ 31706:597f3ee61a48 stable
update Octave Project Developers copyright for the new year
author | John W. Eaton <jwe@octave.org> |
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date | Fri, 06 Jan 2023 13:11:27 -0500 |
parents | 5d3faba0342e |
children | 2e484f9f1f18 |
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######################################################################## ## ## Copyright (C) 1993-2023 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## 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{t} =} 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 function t = trace (A) if (nargin < 1) print_usage (); endif if (ndims (A) > 2) error ("trace: only valid on 2-D objects"); elseif (isempty (A)) t = 0; elseif (isvector (A)) t = A(1); else t = 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 <Invalid call> trace () %!error <only valid on 2-D objects> trace (reshape (1:9,[1,3,3]))