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function magresp(g,varargin);
%-*- texinfo -*-
%@deftypefn {Function} magresp
%@verbatim
%MAGRESP Magnitude response plot of window
% Usage: magresp(g,...);
% magresp(g,fs,...);
% magresp(g,fs,dynrange,....);
%
% MAGRESP(g) will display the magnitude response of the window on a log
% scale (dB);
%
% MAGRESP(g,fs) does the same for windows that are intended to be used
% with signals with sampling rate fs. The x-axis will display Hz.
%
% MAGRESP(g,fs,dynrange) will limit the dynamic range (see below).
%
% MAGRESP takes the following parameters at the end of the line of
% input arguments.
%
% 'dynrange',r Limit the dynamic range of the plot to r dB.
%
% 'fir' Indicate that the input is an FIR window. MAGRESP will
% zero-extend the window to display a smooth magnitude
% response.
%
% 'L',L Zero-extend the window to length L.
%
% 'posfreq' Show only positive frequencies.
%
% 'nf' Show also negative frequencies
%
% 'autoposfreq' Show positive frequencies for real-valued signals,
% otherwise show also the negative frequencies. This is
% the default.
%
% 'opts',op Pass options onto the plot command. The extra options
% op are specified as a cell array
%
% In addition to these flags, it is possible to speficy any of the
% normalization flags from NORMALIZE to normalize the input before
% calculation of the magnitude response. Specifying '1' or 'area' will
% display a magnitude response which peaks at 0 dB.
%
% Examples:
% ---------
%
% The following will display the magnitude response of a Hann window
% of length 20 normalized to a peak of 0 dB:
%
% magresp({'hann',20},'1');
%
% The following will display the magnitude response of a Gaussian window
% of length 100:
%
% magresp('gauss','L',100)
%
% The following passes additional options to the plot command to draw
% in red:
%
% magresp({'nuttall11',30},'opts',{'r'});
%
%@end verbatim
%@strong{Url}: @url{http://ltfat.github.io/doc/sigproc/magresp.html}
%@seealso{demo_gabfir}
%@end deftypefn
% Copyright (C) 2005-2016 Peter L. Soendergaard <peter@sonderport.dk>.
% This file is part of LTFAT version 2.3.1
%
% This program 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.
%
% This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
% AUTHOR : Peter L. Soendergaard.
% TESTING: NA
% REFERENCE: NA
if nargin<1
error('Too few input arguments.');
end;
L=[];
fs=[];
donf=0;
% Define initial value for flags and key/value pairs.
definput.flags.posfreq={'autoposfreq','posfreq','nf'};
definput.import={'normalize'};
definput.importdefaults={'null'};
definput.keyvals.fs=[];
definput.keyvals.opts={};
definput.keyvals.L=[];
definput.flags.wintype={'notype','fir','long'};
definput.keyvals.dynrange=[];
[flags,kv,fs]=ltfatarghelper({'fs','dynrange'},definput,varargin);
[g,info] = comp_fourierwindow(g,kv.L,'MAGRESP');
do_real=flags.do_posfreq;
if flags.do_autoposfreq
do_real=info.wasreal;
end;
if flags.do_fir
info.isfir=1;
end;
if isempty(kv.L)
if info.isfir
% Choose a strange length, such that we don't accidentically hit all
% the zeros in the response.
kv.L=info.gl*13+47;
else
if isempty(info.gl)
% Default value
kv.L=4177;
else
kv.L=info.gl;
end;
end;
end;
if (isstruct(g)) && isfield(g,'fs') && (~isempty(g.fs)) && (isempty(fs))
fs=g.fs;
end;
g=pfilt([1;zeros(kv.L-1,1)],g);
g=normalize(g,flags.norm);
if do_real
% Compute spectrum and normalize
FF=abs(fftreal(real(g)));
% Convert to dB. Add eps to avoid log of zero.
FF=20*log10(FF+realmin);
xmin=0;
else
% Compute spectrum and normalize. fftshift to center correctly for plotting.
FF=fftshift(abs(fft(g)));
% Convert to dB. Add eps to avoid log of zero.
FF=20*log10(FF+realmin);
xmin=-1;
end;
ymax=max(FF);
if ~isempty(kv.dynrange)
ymin=ymax-kv.dynrange;
else
ymin=min(FF);
end;
Lplot=length(FF);
% Only plot positive frequencies for real-valued signals.
if isempty(fs)
xrange=linspace(xmin,1,Lplot).';
axisvec=[xmin 1 ymin ymax];
else
xrange=linspace(xmin*floor(fs/2),floor(fs/2),Lplot).';
axisvec=[xmin*fs/2 fs/2 ymin ymax];
end;
plot(xrange,FF,kv.opts{:});
set(gca,'yscale','linear');
if ymax-ymin~=0
axis(axisvec);
end
ylabel('Magnitude response (dB)');
if isempty(fs)
xlabel('Frequency (normalized) ');
else
xlabel('Frequency (Hz)');
end;
legend('off');
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