freqresp.asv

数字信号处理（机械工业出版社）的源码

function [H,w] = freqresp(b,a,K)
% Computation of frequency response
% ------------------------------------------------------------
% [H,w] = freqresp(b,a,K);
%    K = array of 500 frequency samples between [0 to wmax]
%    b = Numerator polynomial coefficents
%    a = Denominator polynomial coefficents
% w = frequency point row vector for [0,pi] duration
%
m = 0:length(b)-1; l = 0:length(a)-1;
k = 1:1:K;
w = pi*k/K;  % [0, pi] axis divided into K+1 points.
num = b * exp(-j*m'*w); % Numerator calculations
den = a * exp(-j*l'*w); % Denominator calculations
H = num ./ den;