Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/quaternion-2.0.0/@quaternion/subsref.m b/octave_packages/quaternion-2.0.0/@quaternion/subsref.m
new file mode 100644 (file)
index 0000000..32b67b8
--- /dev/null
+++ b/octave_packages/quaternion-2.0.0/@quaternion/subsref.m
@@ -0,0 +1,60 @@
+## Copyright (C) 2010, 2011, 2012   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 -*-
+## Subscripted reference for quaternions.  Used by Octave for "q.w".
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: May 2010
+## Version: 0.4
+
+function ret = subsref (q, s)
+
+  if (numel (s) == 0)
+    ret = q;
+    return;
+  endif
+
+  switch (s(1).type)
+    case "."                                # q.w
+      switch (tolower (s(1).subs))
+        case {"w", "s"}                     # scalar part
+          ret = subsref (q.w, s(2:end));
+        case {"x", "i"}
+          ret = subsref (q.x, s(2:end));
+        case {"y", "j"}
+          ret = subsref (q.y, s(2:end));
+        case {"z", "k"}
+          ret = subsref (q.z, s(2:end));
+        case "v"                            # vector part, scalar part set to zero
+          q.w = zeros (size (q.w));
+          ret = subsref (q, s(2:end));
+        otherwise
+          error ("quaternion: invalid subscript name '%s'", s(1).subs);
+      endswitch
+
+    case "()"                               # q(...)
+      w = subsref (q.w, s(1));
+      x = subsref (q.x, s(1));
+      y = subsref (q.y, s(1));
+      z = subsref (q.z, s(1));
+      tmp = quaternion (w, x, y, z);
+      ret = subsref (tmp, s(2:end));
+      
+    otherwise
+      error ("quaternion: invalid subscript type '%s'", s(1).type);
+  endswitch
+
+endfunction