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mrfit Scilab Group Scilab Function mrfit
NAME
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).
EXAMPLE
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
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