update packages

[CreaPhase.git] / octave_packages / m / polynomial / polyvalm.m

diff --git a/octave_packages/m/polynomial/polyvalm.m b/octave_packages/m/polynomial/polyvalm.m
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+## Copyright (C) 1994-2012 John W. Eaton
+## Copyright (C) 2009 Jaroslav Hajek
+##
+## 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
+## <http://www.gnu.org/licenses/>.
+
+## -*- 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 used in @code{polyval}.
+##
+## The argument @var{x} must be a square matrix.
+## @seealso{polyval, roots, poly}
+## @end deftypefn
+
+## Author: Tony Richardson <arichard@stark.cc.oh.us>
+## 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
+
+  n = length (c);
+  if (n == 0)
+    y = zeros (rows (x), class (x));
+  else
+    id = eye (rows (x), class (x));
+    y = c(1) * id;
+    for i = 2:n
+      y = y * x + c(i) * id;
+    endfor
+  endif
+
+endfunction
+
+
+%!assert(! any (polyvalm ([], [1, 2; 3, 4]))(:));
+%!assert(polyvalm ([1, 2, 3, 4], [3, -4, 1; -2, 0, 2; -1, 4, -3]), [117, -124, 11; -70, 36, 38; -43, 92, -45])
+
+%!error polyvalm ([1, 1, 1], [1, 2; 3, 4; 5, 6]);
+