update packages

[CreaPhase.git] / octave_packages / m / signal / bartlett.m

diff --git a/octave_packages/m/signal/bartlett.m b/octave_packages/m/signal/bartlett.m
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+## Copyright (C) 1995-2012 Andreas Weingessel
+##
+## 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} {} bartlett (@var{m})
+## Return the filter coefficients of a Bartlett (triangular) window of
+## length @var{m}.
+##
+## For a definition of the Bartlett window, see e.g., A. V. Oppenheim &
+## R. W. Schafer, @cite{Discrete-Time Signal Processing}.
+## @end deftypefn
+
+## Author: AW <Andreas.Weingessel@ci.tuwien.ac.at>
+## Description: Coefficients of the Bartlett (triangular) window
+
+function c = bartlett (m)
+
+  if (nargin != 1)
+    print_usage ();
+  endif
+
+  if (! (isscalar (m) && (m == fix (m)) && (m > 0)))
+    error ("bartlett: M has to be an integer > 0");
+  endif
+
+  if (m == 1)
+    c = 1;
+  else
+    m = m - 1;
+    n = fix (m / 2);
+    c = [2*(0:n)/m, 2-2*(n+1:m)/m]';
+  endif
+
+endfunction
+
+%!assert (bartlett (1), 1);
+%!assert (bartlett (2), zeros (2,1));
+%!assert (bartlett (16), fliplr (bartlett (16)));
+%!assert (bartlett (15), fliplr (bartlett (15)));
+%!test
+%! N = 9;
+%! A = bartlett (N);
+%! assert (A (ceil (N/2)), 1);
+
+%!error bartlett ();
+%!error bartlett (0.5);
+%!error bartlett (-1);
+%!error bartlett (ones(1,4));