Scilab Function
Last update : 12/1/2004

frfit - frequency response fit

Calling Sequence

sys=frfit(w,fresp,order)
[num,den]=frfit(w,fresp,order)
sys=frfit(w,fresp,order,weight)
[num,den]=frfit(w,fresp,order,weight)

Parameters

Description

sys=frfit(w,fresp,order,weight) returns a bi-stable transfer function G(s)=sys=num/den, of of given order such that its frequency response G(w(i)) matches fresp(i), i.e. freq(num,den,%i*w) should be close to fresp. weight(i) is the weight given to w(i).

Examples


w=0.01:0.01:2;s=poly(0,'s');
G=syslin('c',2*(s^2+0.1*s+2), (s^2+s+1)*(s^2+0.3*s+1));
fresp=repfreq(G,w);
Gid=frfit(w,fresp,4);
frespfit=repfreq(Gid,w);
bode(w,[fresp;frespfit])
 
  

See Also

frep2tf,  factors,  cepstrum,  mrfit,  freq,  calfrq,