Mercurial > octave
view scripts/linear-algebra/cross.m @ 32060:1203a2d81a42
Add BIST tests for Matlab compatibility for functions which accept negative dimensions.
* data.cc (Fones, Finf, Feps, Feye): Add BIST test for negative dimensions.
* rand.cc (Frand): Add BIST test for negative dimensions.
* ov-cell.cc (Fcell): Add BIST test for negative dimensions.
author | Rik <rik@octave.org> |
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date | Wed, 26 Apr 2023 16:26:32 -0700 |
parents | 597f3ee61a48 |
children | 2e484f9f1f18 |
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######################################################################## ## ## Copyright (C) 1995-2023 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{z} =} cross (@var{x}, @var{y}) ## @deftypefnx {} {@var{z} =} cross (@var{x}, @var{y}, @var{dim}) ## Compute the vector cross product of two 3-dimensional vectors @var{x} and ## @var{y}. ## ## If @var{x} and @var{y} are matrices, the cross product is applied along the ## first dimension with three elements. ## ## The optional argument @var{dim} forces the cross product to be calculated ## along the specified dimension. ## ## Example Code: ## ## @example ## @group ## cross ([1, 1, 0], [0, 1, 1]) ## @result{} ## 1 -1 1 ## @end group ## @end example ## ## @seealso{dot, curl, divergence} ## @end deftypefn function z = cross (x, y, dim) if (nargin < 2) print_usage (); endif if (ndims (x) < 3 && ndims (y) < 3 && nargin < 3) ## COMPATIBILITY -- opposite behavior for cross(row,col) ## Swap x and y in the assignments below to get the matlab behavior. ## Better yet, fix the calling code so that it uses conformant vectors. if (columns (x) == 1 && rows (y) == 1) warning ("cross: taking cross product of column by row"); y = y.'; elseif (rows (x) == 1 && columns (y) == 1) warning ("cross: taking cross product of row by column"); x = x.'; endif endif if (nargin == 2) dim = find (size (x) == 3, 1); if (isempty (dim)) error ("cross: must have at least one dimension with 3 elements"); endif else if (size (x, dim) != 3) error ("cross: dimension DIM must have 3 elements"); endif endif nd = ndims (x); sz = size (x); idx2 = idx3 = idx1 = {':'}(ones (1, nd)); idx1(dim) = 1; idx2(dim) = 2; idx3(dim) = 3; if (size_equal (x, y)) x1 = x(idx1{:}); x2 = x(idx2{:}); x3 = x(idx3{:}); y1 = y(idx1{:}); y2 = y(idx2{:}); y3 = y(idx3{:}); z = cat (dim, (x2.*y3 - x3.*y2), (x3.*y1 - x1.*y3), (x1.*y2 - x2.*y1)); else error ("cross: X and Y must have the same dimensions"); endif endfunction %!test %! x = [1 0 0]; %! y = [0 1 0]; %! r = [0 0 1]; %! assert (cross (x, y), r, 2e-8); %!test %! x = [1 2 3]; %! y = [4 5 6]; %! r = [(2*6-3*5) (3*4-1*6) (1*5-2*4)]; %! assert (cross (x, y), r, 2e-8); %!test %! x = [1 0 0; 0 1 0; 0 0 1]; %! y = [0 1 0; 0 0 1; 1 0 0]; %! r = [0 0 1; 1 0 0; 0 1 0]; %! assert (cross (x, y, 2), r, 2e-8); %! assert (cross (x, y, 1), -r, 2e-8); ## Test input validation %!error <Invalid call> cross () %!error <Invalid call> cross (1) ## FIXME: Need tests for other error() conditions and warning() calls. %!error <must have at least one dimension with 3 elements> cross (0,0)