相关代码打开matlab源码也可以看到，这里做了简单实现，与源码并不完全一样。

实现代码

[h2 w2] = freqzfir(data);   [h1 w1] = freqz(data);   h2=h2'; h12 = [h1, h2];  [h4 w4] = freqziir(b,a, 2001,true); [h3 w3] = freqz(b,a, w4', 'whole'); h4 = h4'; h34 = h3-h4;  function y = mpolyval(x, c)      y = zeros(size(x));     y(:) = c(1);     for i = 2:length(c)         y = x .* y + c(i);     end end  function [h, w] = freqziir(b, a, count, whole)          if whole         lastpoint = 2 * pi;     else         lastpoint = pi;     end          w = [0:count-1]./count.*lastpoint; %     w = w';     c = 0 - 1i;     zm1 = exp(c * w);             h1 = mpolyval(zm1, a);     h2 = mpolyval(zm1, b);     h = h2./h1; end  function [h, w] = freqzfir(b)     a = [1];     count = 512;     n  = length(b);     whole = false;          if whole         lastpoint = 2 * pi;     else         lastpoint = pi;     end          w = [0:count-1]./count.*lastpoint; %     w = w';     c = 0 - 1i;     zm1 = exp(c * w);      mh2 = mpolyval(zm1, b);           mh1 = exp(-1i*w*(n-1));     mh = mh2./mh1;     h = mh; end