dfrqint2.m

数字通信第四版原书的例程

function w=dfrqint2(a,b,c,d,Ts,npts)
%DFRQINT2 Discrete auto-ranging algorithm for Nyquist and Nichols plots.
%
%	W=DFRQINT2(A,B,C,D,Ts,NPTS)
%	W=DFRQINT2(NUM,DEN,Ts,NPTS)

%	Clay M. Thompson 7-10-90
%	Copyright (c) 1986-93 by the MathWorks, Inc.

if nargin==4,
  Ts = c; npts = d;
  [a,b,c,d] = tf2ss(a,b);
end
[a1,b1] = d2c(a,b,Ts);
w=freqint2(a1,b1,c,d,npts);
w=w(find(w<=pi/Ts));
if ~isempty(w), 
  w=sort([w;linspace(min(w),pi/Ts,128).']);
else
  w=linspace(pi/Ts/10,pi/Ts,128).';
end