mrfit - frequency response fit

Calling Sequence

sys=mrfit(w,mag,order)

[num,den]=mrfit(w,mag,order)

sys=mrfit(w,mag,order,weight)

[num,den]=mrfit(w,mag,order,weight)

Parameters

• w : positive real vector of frequencies (Hz)
• mag : real vector of frequency responses magnitude (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=mrfit(w,mag,order,weight) returns a bi-stable transfer function G(s)=sys=num/den, of of given order such that its frequency response magnitude abs(G(w(i))) matches mag(i) i.e. abs(freq(num,den,%i*w)) should be close to mag. weight(i) is the weigth 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)); // syslin('c',Num,Den);
fresp=repfreq(G,w);
mag=abs(fresp);
Gid=mrfit(w,mag,4);
frespfit=repfreq(Gid,w);
plot2d([w',w'],[mag(:),abs(frespfit(:))])
 

See Also

cepstrum  frfit  freq  calfrq