## Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2004,
## 2005, 2006, 2007 John W. Eaton
##
## This file is part of Octave.
##
## Octave 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.
##
## Octave 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 Octave; see the file COPYING. If not, see
## .
## -*- texinfo -*-
## @deftypefn {Function File} {} polyvalm (@var{c}, @var{x})
## Evaluate a polynomial in the matrix sense.
##
## @code{polyvalm (@var{c}, @var{x})} will evaluate the polynomial in the
## matrix sense, i.e. matrix multiplication is used instead of element by
## element multiplication as is used in polyval.
##
## The argument @var{x} must be a square matrix.
## @seealso{polyval, poly, roots, conv, deconv, residue, filter,
## polyderiv, polyinteg}
## @end deftypefn
## Author: Tony Richardson
## Created: June 1994
## Adapted-By: jwe
function y = polyvalm (c, x)
if (nargin != 2)
print_usage ();
endif
if (! (isvector (c) || isempty (c)))
error ("polyvalm: first argument must be a vector");
endif
if (! issquare (x))
error ("polyvalm: second argument must be a square matrix");
endif
if (isempty (c))
y = [];
return;
endif
[v, d] = eig (x);
if (issymmetric (x))
y = v * diag (polyval (c, diag (d))) * v';
else
y = v * (diag (polyval (c, diag (d))) / v);
endif
endfunction
//%!assert(isempty (polyvalm ([], [1, 2; 3, 4])));
//%!error polyvalm ([1, 1, 1], [1, 2; 3, 4; 5, 6]);