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Aide de Scilab >> Traitement du Signal > Identification > frfit

frfit

frequency response fit

Syntax

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

Arguments

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 — transfer function realization from frequency response
  • factors — factorise dans ℝ un polynôme ou une fraction rationelle
  • cepstrum — cepstrum calculation
  • mrfit — frequency response fit
  • freq — frequency response
  • calfrq — frequency response discretization
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Last updated:
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