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view scripts/signal/freqz.m @ 28789:28de41192f3c
Eliminate unneeded verification of nargin, nargout in m-files.
* FIRfilter.m, FIRfilter_aggregation.m, get.m, polynomial.m,
polynomial_superiorto.m, polynomial2.m, makeUniqueStrings.m, base64decode.m,
base64encode.m, cd.m, lin2mu.m, record.m, sound.m, soundsc.m, accumarray.m,
accumdim.m, bitcmp.m, bitset.m, cart2pol.m, celldisp.m, circshift.m,
cplxpair.m, cumtrapz.m, flip.m, idivide.m, interpft.m, logspace.m, pol2cart.m,
polyarea.m, postpad.m, prepad.m, rat.m, rot90.m, rotdim.m, shift.m, shiftdim.m,
sortrows.m, trapz.m, dsearch.m, dsearchn.m, getappdata.m, getpixelposition.m,
guidata.m, guihandles.m, isappdata.m, listfonts.m, uigetdir.m,
waitforbuttonpress.m, __makeinfo__.m, doc.m, get_first_help_sentence.m,
autumn.m, bone.m, brighten.m, cmpermute.m, cmunique.m, colorcube.m, contrast.m,
cool.m, copper.m, cubehelix.m, flag.m, gray.m, gray2ind.m, hot.m, hsv.m,
im2double.m, im2frame.m, imformats.m, jet.m, lines.m, ocean.m, pink.m, prism.m,
rainbow.m, rgbplot.m, spinmap.m, spring.m, summer.m, viridis.m, white.m,
winter.m, beep.m, importdata.m, is_valid_file_id.m, javachk.m, javaclasspath.m,
findstr.m, genvarname.m, strmatch.m, bandwidth.m, commutation_matrix.m, cond.m,
cross.m, isdefinite.m, ishermitian.m, issymmetric.m, krylov.m, linsolve.m,
logm.m, lscov.m, null.m, ordeig.m, orth.m, rank.m, rref.m, vecnorm.m,
bunzip2.m, citation.m, computer.m, copyfile.m, dir.m, dos.m, fileattrib.m,
gunzip.m, inputParser.m, inputname.m, ismac.m, ispc.m, isunix.m, license.m,
list_primes.m, methods.m, mkdir.m, movefile.m, nargchk.m, news.m,
orderfields.m, recycle.m, tar.m, unix.m, unpack.m, untar.m, unzip.m, ver.m,
version.m, what.m, zip.m, decic.m, fminbnd.m, fminunc.m, fsolve.m, fzero.m,
glpk.m, humps.m, lsqnonneg.m, optimget.m, pqpnonneg.m, sqp.m, pathdef.m,
camlookat.m, hidden.m, specular.m, plotmatrix.m, smooth3.m, sombrero.m,
stemleaf.m, __gnuplot_drawnow__.m, __opengl_info__.m, ancestor.m, cla.m,
close.m, closereq.m, copyobj.m, gca.m, gcf.m, ginput.m, graphics_toolkit.m,
groot.m, hgload.m, hgsave.m, isgraphics.m, ishold.m, linkaxes.m, meshgrid.m,
newplot.m, refresh.m, refreshdata.m, rotate.m, saveas.m, struct2hdl.m, conv.m,
mkpp.m, mpoles.m, padecoef.m, pchip.m, polyder.m, polyfit.m, polygcd.m,
polyint.m, polyout.m, polyval.m, ppder.m, ppint.m, getpref.m, ispref.m,
rmpref.m, profexport.m, profshow.m, powerset.m, arch_fit.m, arma_rnd.m,
blackman.m, detrend.m, diffpara.m, fftconv.m, fftfilt.m, filter2.m, freqz.m,
freqz_plot.m, hamming.m, hanning.m, sinetone.m, sinewave.m, spectral_adf.m,
spectral_xdf.m, stft.m, unwrap.m, gplot.m, ichol.m, ilu.m, spdiags.m, sprand.m,
sprandn.m, spstats.m, svds.m, treelayout.m, treeplot.m, betainc.m,
betaincinv.m, ellipke.m, gammainc.m, gammaincinv.m, legendre.m, pow2.m,
hankel.m, pascal.m, rosser.m, toeplitz.m, bounds.m, corr.m, cov.m, histc.m,
kendall.m, kurtosis.m, mad.m, mode.m, moment.m, prctile.m, quantile.m, range.m,
ranks.m, run_count.m, skewness.m, spearman.m, std.m, var.m, zscore.m,
dec2base.m, dec2bin.m, dec2hex.m, index.m, mat2str.m, native2unicode.m,
ostrsplit.m, strjoin.m, strjust.m, strtok.m, substr.m, unicode2native.m,
untabify.m, __debug_octave__.m, demo.m, example.m, fail.m, oruntests.m,
dump_demos.m, speed.m, test.m, date.m, datenum.m, datestr.m, datevec.m,
is_leap_year.m, now.m, weekday.m:
Eliminate unneeded verification of nargin, nargout in m-files now that
the interpreter checks these values.
author | Rik <rik@octave.org> |
---|---|
date | Thu, 24 Sep 2020 14:44:58 -0700 |
parents | a4268efb7334 |
children | 7854d5752dd2 |
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######################################################################## ## ## Copyright (C) 1994-2020 The Octave Project Developers ## ## See the file COPYRIGHT.md in the top-level directory of this ## distribution or <https://octave.org/copyright/>. ## ## 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 ## <https://www.gnu.org/licenses/>. ## ######################################################################## ## -*- texinfo -*- ## @deftypefn {} {[@var{h}, @var{w}] =} freqz (@var{b}, @var{a}, @var{n}, "whole") ## @deftypefnx {} {[@var{h}, @var{w}] =} freqz (@var{b}) ## @deftypefnx {} {[@var{h}, @var{w}] =} freqz (@var{b}, @var{a}) ## @deftypefnx {} {[@var{h}, @var{w}] =} freqz (@var{b}, @var{a}, @var{n}) ## @deftypefnx {} {@var{h} =} freqz (@var{b}, @var{a}, @var{w}) ## @deftypefnx {} {[@var{h}, @var{w}] =} freqz (@dots{}, @var{Fs}) ## @deftypefnx {} {} freqz (@dots{}) ## ## Return the complex frequency response @var{h} of the rational IIR filter ## whose numerator and denominator coefficients are @var{b} and @var{a}, ## respectively. ## ## The response is evaluated at @var{n} angular frequencies between 0 and ## @ifnottex ## 2*pi. ## @end ifnottex ## @tex ## $2\pi$. ## @end tex ## ## @noindent ## The output value @var{w} is a vector of the frequencies. ## ## If @var{a} is omitted, the denominator is assumed to be 1 (this ## corresponds to a simple FIR filter). ## ## If @var{n} is omitted, a value of 512 is assumed. For fastest computation, ## @var{n} should factor into a small number of small primes. ## ## If the fourth argument, @qcode{"whole"}, is omitted the response is ## evaluated at frequencies between 0 and ## @ifnottex ## pi. ## @end ifnottex ## @tex ## $\pi$. ## @end tex ## ## @code{freqz (@var{b}, @var{a}, @var{w})} ## ## Evaluate the response at the specific frequencies in the vector @var{w}. ## The values for @var{w} are measured in radians. ## ## @code{[@dots{}] = freqz (@dots{}, @var{Fs})} ## ## Return frequencies in Hz instead of radians assuming a sampling rate ## @var{Fs}. If you are evaluating the response at specific frequencies ## @var{w}, those frequencies should be requested in Hz rather than radians. ## ## @code{freqz (@dots{})} ## ## Plot the magnitude and phase response of @var{h} rather than returning them. ## ## @seealso{freqz_plot} ## @end deftypefn function [h_r, f_r] = freqz (b, a, n, region, Fs) if (nargin < 1) print_usage (); elseif (nargin == 1) ## Response of an FIR filter. a = n = region = Fs = []; elseif (nargin == 2) ## Response of an IIR filter n = region = Fs = []; elseif (nargin == 3) region = Fs = []; elseif (nargin == 4) Fs = []; if (! ischar (region) && ! isempty (region)) Fs = region; region = []; endif endif if (isempty (b)) b = 1; elseif (! isvector (b)) error ("freqz: B must be a vector"); endif if (isempty (a)) a = 1; elseif (! isvector (a)) error ("freqz: A must be a vector"); endif if (isempty (n)) n = 512; elseif (isscalar (n) && n < 1) error ("freqz: N must be a positive integer"); endif if (isempty (region)) if (isreal (b) && isreal (a)) region = "half"; else region = "whole"; endif endif if (isempty (Fs)) freq_norm = true; if (nargout == 0) Fs = 2; else Fs = 2*pi; endif else freq_norm = false; endif plot_output = (nargout == 0); whole_region = strcmp (region, "whole"); a = a(:); b = b(:); if (! isscalar (n)) ## Explicit frequency vector given w = f = n; if (nargin == 4) ## Sampling rate Fs was specified w = 2*pi*f/Fs; endif k = max (length (b), length (a)); hb = polyval (postpad (b, k), exp (j*w)); ha = polyval (postpad (a, k), exp (j*w)); else ## polyval(fliplr(P),exp(jw)) is O(p n) and fft(x) is O(n log(n)), ## where p is the order of the polynomial P. For small p it ## would be faster to use polyval but in practice the overhead for ## polyval is much higher and the little bit of time saved isn't ## worth the extra code. k = max (length (b), length (a)); if (k > n/2 && nargout == 0) ## Ensure a causal phase response. n *= 2 .^ ceil (log2 (2*k/n)); endif if (whole_region) N = n; if (plot_output) f = Fs * (0:n).' / N; # do 1 more for the plot else f = Fs * (0:n-1).' / N; endif else N = 2*n; if (plot_output) n += 1; endif f = Fs * (0:n-1).' / N; endif pad_sz = N*ceil (k/N); b = postpad (b, pad_sz); a = postpad (a, pad_sz); hb = zeros (n, 1); ha = zeros (n, 1); for i = 1:N:pad_sz hb += fft (postpad (b(i:i+N-1), N))(1:n); ha += fft (postpad (a(i:i+N-1), N))(1:n); endfor endif h = hb ./ ha; if (plot_output) ## Plot and don't return values. if (whole_region && isscalar (n)) h(end+1) = h(1); # Solution is periodic. Copy first value to end. endif freqz_plot (f, h, freq_norm); else ## Return values and don't plot. h_r = h; f_r = f; endif endfunction %!testif HAVE_FFTW # correct values and fft-polyval consistency %! ## butterworth filter, order 2, cutoff pi/2 radians %! b = [0.292893218813452 0.585786437626905 0.292893218813452]; %! a = [1 0 0.171572875253810]; %! [h,w] = freqz (b,a,32); %! assert (h(1),1,10*eps); %! assert (abs (h(17)).^2,0.5,10*eps); %! assert (h,freqz (b,a,w),10*eps); # fft should be consistent with polyval %!testif HAVE_FFTW # whole-half consistency %! b = [1 1 1]/3; # 3-sample average %! [h,w] = freqz (b,1,32,"whole"); %! assert (h(2:16),conj (h(32:-1:18)),20*eps); %! [h2,w2] = freqz (b,1,16,"half"); %! assert (h(1:16),h2,20*eps); %! assert (w(1:16),w2,20*eps); %!testif HAVE_FFTW # Sampling frequency properly interpreted %! b = [1 1 1]/3; a = [1 0.2]; %! [h,f] = freqz (b,a,16,320); %! assert (f,[0:15]'*10,10*eps); %! [h2,f2] = freqz (b,a,[0:15]*10,320); %! assert (f2,[0:15]*10,10*eps); %! assert (h,h2.',20*eps); %! [h3,f3] = freqz (b,a,32,"whole",320); %! assert (f3,[0:31]'*10,10*eps); ## Test input validation ## FIXME: Need to put tests here and simplify input validation in the main code.