ltrn.m

很多matlab的源代码

function [tf,rr,pp,kk] = ltrn(x)
%LTRN	Support file for LTR


% ADSP Toolbox: Version 2.0 
% For use with "Analog and Digital Signal Processing", 2nd Ed.
% Published by PWS Publishing Co.
%
% Ashok Ambardar, EE Dept. MTU, Houghton, MI 49931, USA
% http://www.ee.mtu/faculty/akambard.html
% e-mail: [e-mail]
% Copyright (c) 1998


if nargin==0,help ltrn,return,end

lx=length(x);while x(lx)==0,x(lx)=[];lx=lx-1;end
m=x(1);a=0;p=0;w=0;r=0;n0=0;
if lx>1,a=x(2);end,if lx>2,p=x(3);end,if lx>3,w=x(4);end,if lx>4,r=x(5);end
if p<0,error('powers of t cannot be negative'),return,end
if w<0,w=-w;r=-r;end
if m==0,tf=[0;1];return,end
if lx<3,tf=[0 m;1 a];return,end
if w==0,na=1;da=[1 a];rt=-a;m=m*cos(r);
else
na=[cos(r) a*cos(r)-w*sin(r)];
da=[1 2*a a*a+w*w];rt=-a+j*w;rt=[rt;conj(rt)];end
rt1=rt;if p>0,d=da;ln=length(na);
for n=1:p,if ln==1,n1=-n*na;else,n1=-n*conv(na,[2 2*a]);end
l=length(na);
k=l-1:-1:0;dna=na.*k;dna(l)=[];n2=conv(dna,d);
l1=length(n1);l2=length(n2);ld=l1-l2;
if ld>0,n2=[zeros(1,ld) n2];end,if ld<0,n1=[zeros(1,-ld) n1];end
na=[-(n1+n2)];da=conv(da,d);rt=[rt;rt1];end,end
na=m*na.*(abs(na)>75*eps);da=da.*(abs(da)>75*eps);
l1=length(na);l2=length(da);ld=l1-l2;
if ld>0,da=[zeros(1,ld) da];end,if ld<0,na=[zeros(1,-ld) na];end
tf=[na;da];
if nargout>1,[rr,pp,kk]=tf2pf(na,rt,1,.1*abs(a));end