Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / linear-algebra-2.2.0 / @kronprod / mpower.m

diff --git a/octave_packages/linear-algebra-2.2.0/@kronprod/mpower.m b/octave_packages/linear-algebra-2.2.0/@kronprod/mpower.m
new file mode 100644 (file)
index 0000000..9800e6b
--- /dev/null
+++ b/octave_packages/linear-algebra-2.2.0/@kronprod/mpower.m
@@ -0,0 +1,44 @@
+## Copyright (C) 2010  Soren Hauberg
+## 
+## 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, 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 file.  If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} mpower (@var{KP}, @var{k})
+## XXX: Write documentation
+## @end deftypefn
+
+function retval = mpower (KP, k)
+  ## Check input
+  if (nargin != 2)
+    print_usage ();
+  endif
+  
+  if (!ismatrix (KP))
+    error ("mpower: first input argument must be a matrix");
+  endif
+  
+  if (!isscalar (k))
+    error ("mpower: second input argument must be a scalar");
+  endif
+
+  ## Do the actual computation
+  if (issquare (KP.A) && issquare (KP.B) && k == round (k))
+    retval = kronprod (KP.A^k, KP.B^k);
+  elseif (issquare (KP))
+    ## XXX: Can we do something smarter here?
+    retval = full (KP)^k;
+  else
+    error ("for A^b, A must be square");
+  endif
+endfunction