Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/linear-algebra-2.2.0/@kronprod/full.m b/octave_packages/linear-algebra-2.2.0/@kronprod/full.m
new file mode 100644 (file)
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+++ b/octave_packages/linear-algebra-2.2.0/@kronprod/full.m
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+## 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} full (@var{KP})
+## Return the full matrix representation of the Kronecker product @var{KP}.
+##
+## If @var{KP} is the Kronecker product of an @var{n}-by-@var{m} matrix and a
+## @var{q}-by-@var{r} matrix, then the result is a @var{n}@var{q}-by-@var{m}@var{r}
+## matrix. Thus, the result can require vast amount of memory, so this function
+## should be avoided whenever possible.
+## @seealso{full, @@kronprod/sparse}
+## @end deftypefn
+
+function retval = full (KP)
+  if (nargin != 1)
+    print_usage ();
+  endif
+  
+  if (!isa (KP, "kronprod"))
+    error ("full: input argument must be of class 'kronprod'");
+  endif
+  
+  retval = full (kron (KP.A, KP.B));
+  if (!isempty (KP.P))
+    #retval = KP.P * retval * KP.P';
+    retval = retval (KP.P, KP.P);
+  endif
+endfunction