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
-
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,