Mercurial > octave
view scripts/signal/blackman.m @ 21581:6fab85c1538f
maint: Follow Octave conventions for use of semicolon in BIST tests.
* testfun.txi: Document Octave conventions for use of semicolon in BIST tests.
* cellfun.cc, ellipj.cc, file-io.cc, gcd.cc, hash.cc, nproc.cc,
utils.cc, fftw.cc, ov-usr-fcn.cc, oct-parse.in.yy, md5sum.m, wavread.m, wavwrite.m,
cplxpair.m, rat.m, im2double.m, rref.m, stem3.m, rotate.m, pchip.m, blackman.m,
hamming.m, hanning.m, spectral_adf.m, spectral_xdf.m, assert.m, fail.m,
etime.m, build-sparse-tests.sh, classes.tst, ctor-vs-method.tst, index.tst,
io.tst, struct.tst: Follow Octave conventions for use of semicolon in BIST
tests.
author | Rik <rik@octave.org> |
---|---|
date | Fri, 01 Apr 2016 18:16:01 -0700 |
parents | a4faec57f4c8 |
children | bac0d6f07a3e |
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## Copyright (C) 1995-2015 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 {} {} blackman (@var{m}) ## @deftypefnx {} {} blackman (@var{m}, "periodic") ## @deftypefnx {} {} blackman (@var{m}, "symmetric") ## Return the filter coefficients of a Blackman window of length @var{m}. ## ## If the optional argument @qcode{"periodic"} is given, the periodic form ## of the window is returned. This is equivalent to the window of length ## @var{m}+1 with the last coefficient removed. The optional argument ## @qcode{"symmetric"} is equivalent to not specifying a second argument. ## ## For a definition of the Blackman window, see, e.g., ## @nospell{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, opt) if (nargin < 1 || nargin > 2) print_usage (); endif if (! (isscalar (m) && (m == fix (m)) && (m > 0))) error ("blackman: M must be a positive integer"); endif N = m - 1; if (nargin == 2) switch (opt) case "periodic" N = m; case "symmetric" ## Default option, same as no option specified. otherwise error ('blackman: window type must be either "periodic" or "symmetric"'); endswitch endif if (m == 1) c = 1; else m -= 1; k = (0 : m)' / N; 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 (15), flip (blackman (15)), 5*eps) %!assert (blackman (16), flip (blackman (16)), 5*eps) %!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); %!assert (blackman (15), blackman (15, "symmetric")) %!assert (blackman (16)(1:15), blackman (15, "periodic")) %!test %! N = 16; %! A = blackman (N, "periodic"); %! assert (A(N/2 + 1), 1, 1e-6); %!error blackman () %!error blackman (0.5) %!error blackman (-1) %!error blackman (ones (1,4)) %!error blackman (1, "invalid")