frfit
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
| w | : positive real vector of frequencies (Hz) |
| fresp | : complex vector of frequency responses (same size as w) |
| order | : integer (required order, degree of den) |
| weight | : positive real vector (default value ones(w)). |
| num,den | : stable polynomials |
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
