Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / nurbs-1.3.6 / veccross.m

diff --git a/octave_packages/nurbs-1.3.6/veccross.m b/octave_packages/nurbs-1.3.6/veccross.m
new file mode 100644 (file)
index 0000000..877c0fa
--- /dev/null
+++ b/octave_packages/nurbs-1.3.6/veccross.m
@@ -0,0 +1,59 @@
+function cross = veccross(vec1,vec2)
+% 
+% VECCROSS: The cross product of two vectors.
+% 
+% Calling Sequence:
+% 
+%   cross = veccross(vec1,vec2);
+% 
+% INPUT:
+% 
+%   vec1       : An array of column vectors represented by a matrix of
+%   vec2       size (dim,nv), where is the dimension of the vector and
+%              nv the number of vectors.
+%
+% OUTPUT:
+% 
+%   cross      : Array of column vectors, each element is corresponding
+%              to the cross product of the respective components in vec1
+%              and vec2.
+% 
+% Description:
+% 
+%   Cross product of two vectors.
+% 
+% Examples:
+% 
+%   Determine the cross products of:
+%   (2.3,3.4,5.6) and (1.2,4.5,1.2)
+%   (5.1,0.0,2.3) and (2.5,3.2,4.0)
+% 
+%   cross = veccross([2.3 5.1; 3.4 0.0; 5.6 2.3],[1.2 2.5; 4.5 3.2; 1.2 4.0]);
+%
+%    Copyright (C) 2000 Mark Spink
+%
+%    This program 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 2 of the License, or
+%    (at your option) any later version.
+
+%    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if size(vec1,1) == 2
+  % 2D vector
+  cross = zeros(size(vec1));
+  cross(3,:) = vec1(1,:).*vec2(2,:)-vec1(2,:).*vec2(1,:);
+else
+  % 3D vector
+  cross = [vec1(2,:).*vec2(3,:)-vec1(3,:).*vec2(2,:);
+           vec1(3,:).*vec2(1,:)-vec1(1,:).*vec2(3,:);
+           vec1(1,:).*vec2(2,:)-vec1(2,:).*vec2(1,:)];
+end
+
+end