update packages

[CreaPhase.git] / octave_packages / m / deprecated / sylvester_matrix.m

diff --git a/octave_packages/m/deprecated/sylvester_matrix.m b/octave_packages/m/deprecated/sylvester_matrix.m
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+## Copyright (C) 1996-2012 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
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} sylvester_matrix (@var{k})
+## Return the Sylvester matrix of order
+## @tex
+## $n = 2^k$.
+## @end tex
+## @ifnottex
+## n = 2^@var{k}.
+## @end ifnottex
+##
+## @seealso{toeplitz, hankel}
+## @end deftypefn
+
+## Author: jwe
+
+function retval = sylvester_matrix (k)
+
+  persistent warned = false;
+  if (! warned)
+    warned = true;
+    warning ("Octave:deprecated-function",
+             "sylvester_matrix is obsolete and will be removed from a future version of Octave; please use hadamard(2^k) instead");
+  endif
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  if (isscalar (k))
+    if (k < 1)
+      retval = 1;
+    else
+      tmp = sylvester_matrix (k-1);
+      retval = [tmp, tmp; tmp, -tmp];
+    endif
+  else
+    error ("sylvester_matrix: expecting scalar argument");
+  endif
+
+endfunction
+
+%!assert((sylvester_matrix (1) == [1, 1; 1, -1]
+%! && (sylvester_matrix (2)
+%! == [1, 1, 1, 1; 1, -1, 1, -1; 1, 1, -1, -1; 1, -1, -1, 1])));
+
+%!error sylvester_matrix ([1, 2; 3, 4]);
+
+%!error sylvester_matrix ();
+
+%!error sylvester_matrix (1, 2);
+