1 ## Copyright (C) 2003 Julius O. Smith III <jos@ccrma.stanford.edu>
3 ## This program is free software; you can redistribute it and/or modify it under
4 ## the terms of the GNU General Public License as published by the Free Software
5 ## Foundation; either version 3 of the License, or (at your option) any later
8 ## This program is distributed in the hope that it will be useful, but WITHOUT
9 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
13 ## You should have received a copy of the GNU General Public License along with
14 ## this program; if not, see <http://www.gnu.org/licenses/>.
16 ## Usage: H = freqs(B,A,W);
18 ## Compute the s-plane frequency response of the IIR filter B(s)/A(s) as
19 ## H = polyval(B,j*W)./polyval(A,j*W). If called with no output
20 ## argument, a plot of magnitude and phase are displayed.
23 ## B = [1 2]; A = [1 1];
24 ## w = linspace(0,4,128);
27 function [H] = freqs(B,A,W)
29 if (nargin ~= 3 || nargout>1)
33 H = polyval(B,j*W)./polyval(A,j*W);
44 %! w = linspace(0,4,128);