Mercurial > octave-dspies
view scripts/signal/blackman.m @ 18995:8ac4ab4ae5f4
periodogram.m: Overhaul function (bug #39279, bug #42859).
* contributors.in: Add Drew Abbot to list of contributors.
* periodogram.m: Rewrite documentation. Simplify input parsing of arguments.
Accept both row and column inputs for X. Correct onesided computation
when NFFT is odd. Add an error message about unrecognized range specification
"centered". Add input validation tests.
author | Drew Abbot <drewabbot@gmail.com> and Rik <rik@octave.org> |
---|---|
date | Thu, 07 Aug 2014 10:13:30 -0700 |
parents | d63878346099 |
children |
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## Copyright (C) 1995-2013 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} {} blackman (@var{m}) ## Return the filter coefficients of a Blackman window of length @var{m}. ## ## For a definition of the Blackman 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 Blackman window function c = blackman (m) if (nargin != 1) print_usage (); endif if (! (isscalar (m) && (m == fix (m)) && (m > 0))) error ("blackman: M has to be an integer > 0"); endif if (m == 1) c = 1; else m = m - 1; k = (0 : m)' / m; c = 0.42 - 0.5 * cos (2 * pi * k) + 0.08 * cos (4 * pi * k); endif endfunction %!assert (blackman (1), 1) %!assert (blackman (2), zeros (2,1), 1e-6) %!assert (blackman (16), fliplr (blackman (16))) %!assert (blackman (15), fliplr (blackman (15))) %!test %! N = 9; %! A = blackman (N); %! assert (A (ceil (N/2)), 1, 1e-6); %! assert ([A(1), A(length (A))], zeros (1, 2), 1e-6); %!error blackman () %!error blackman (0.5) %!error blackman (-1) %!error blackman (ones (1,4))