Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/nurbs-1.3.6/vecrotx.m b/octave_packages/nurbs-1.3.6/vecrotx.m
new file mode 100644 (file)
index 0000000..8b03721
--- /dev/null
+++ b/octave_packages/nurbs-1.3.6/vecrotx.m
@@ -0,0 +1,62 @@
+function rx = vecrotx(angle)
+% 
+% VECROTX: Transformation matrix for a rotation around the x axis. 
+% 
+% Calling Sequence:
+% 
+%   rx = vecrotx(angle);
+% 
+% INPUT:
+% 
+%   angle              : rotation angle defined in radians
+%
+% OUTPUT:
+% 
+%   rx         : (4x4) Transformation matrix.
+% 
+% 
+% Description:
+% 
+%   Return the (4x4) Transformation matrix for a rotation about the x axis
+%   by the defined angle.
+% 
+%   The matrix is:
+% 
+%         [ 1         0            0          0]
+%         [ 0     cos(angle)  -sin(angle)     0]
+%         [ 0     sin(angle)   cos(angle)     0]
+%         [ 0         0            0          1]
+% 
+% Examples:
+% 
+%    Rotate the NURBS line (0.0 0.0 0.0) - (3.0 3.0 3.0) by 45 degrees
+%    around the x-axis
+% 
+%    line = nrbline([0.0 0.0 0.0],[3.0 3.0 3.0]);
+%    trans = vecrotx(%pi/4);
+%    rline = nrbtform(line, trans);
+% 
+% See also:
+% 
+%    nrbtform
+%
+%    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/>.
+
+sn = sin(angle);
+cn = cos(angle);
+rx = [1 0 0 0; 0 cn -sn 0; 0 sn cn 0; 0 0 0 1];
+
+end