Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / quaternion-2.0.0 / @quaternion / quaternion.m

diff --git a/octave_packages/quaternion-2.0.0/@quaternion/quaternion.m b/octave_packages/quaternion-2.0.0/@quaternion/quaternion.m
new file mode 100644 (file)
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+++ b/octave_packages/quaternion-2.0.0/@quaternion/quaternion.m
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+## Copyright (C) 2010, 2011   Lukas F. Reichlin
+##
+## 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 3 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/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{q} =} quaternion (@var{w})
+## @deftypefnx {Function File} {@var{q} =} quaternion (@var{x}, @var{y}, @var{z})
+## @deftypefnx {Function File} {@var{q} =} quaternion (@var{w}, @var{x}, @var{y}, @var{z})
+## Constructor for quaternions - create or convert to quaternion.
+##
+## @example
+## q = w + x*i + y*j + z*k
+## @end example
+##
+## Arguments @var{w}, @var{x}, @var{y} and @var{z} can be scalars or
+## matrices, but they must be real and of equal size.  If scalar part
+## @var{w} or components @var{x}, @var{y} and @var{z} of the vector
+## part are not specified, zero matrices of appropriate size are
+## assumed.
+##
+## @strong{Example}
+## @example
+## @group
+## octave:1> q = quaternion (2)
+## q = 2 + 0i + 0j + 0k
+## 
+## octave:2> q = quaternion (3, 4, 5)
+## q = 0 + 3i + 4j + 5k
+## 
+## octave:3> q = quaternion (2, 3, 4, 5)
+## q = 2 + 3i + 4j + 5k
+## @end group
+## @end example
+## @example
+## @group
+## octave:4> w = [2, 6, 10; 14, 18, 22];
+## octave:5> x = [3, 7, 11; 15, 19, 23];
+## octave:6> y = [4, 8, 12; 16, 20, 24];
+## octave:7> z = [5, 9, 13; 17, 21, 25];
+## octave:8> q = quaternion (w, x, y, z)
+## q.w =
+##     2    6   10
+##    14   18   22
+## 
+## q.x =
+##     3    7   11
+##    15   19   23
+## 
+## q.y =
+##     4    8   12
+##    16   20   24
+## 
+## q.z =
+##     5    9   13
+##    17   21   25
+## 
+## octave:9> 
+## @end group
+## @end example
+##
+## @end deftypefn
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: May 2010
+## Version: 0.2
+
+function q = quaternion (a, b, c, d)
+
+  switch (nargin)
+    case 1
+      if (isa (a, "quaternion"))        # quaternion (q)
+        q = a;
+        return;
+      elseif (is_real_array (a))        # quaternion (w)
+        b = c = d = zeros (size (a));
+      else
+        print_usage ();
+      endif
+    case 3                              # quaternion (x, y, z)
+      d = c;
+      c = b;
+      b = a;
+      a = zeros (size (a));
+    case 4                              # quaternion (w, x, y, z)
+      ## nothing to do here, just prevent case "otherwise"
+    otherwise
+      print_usage ();
+  endswitch
+
+  if (! is_real_array (a, b, c, d))
+    error ("quaternion: arguments must be real matrices");
+  endif
+
+  if (! size_equal (a, b, c, d));
+    error ("quaternion: arguments must have identical sizes");
+  endif
+
+  q = class (struct ("w", a, "x", b, "y", c, "z", d), "quaternion");
+
+endfunction