Examples
[B,A] = butter(4,1/4); [H,F] = freqz(B,A); [Bh,Ah,C] = invfreq(H,F,4,4) Bh = 0.010209 0.040838 0.061257 0.040838 0.010209 Ah = 1.00000 -1.96843 1.73586 -0.72447 0.12039 C = -7.7065e-15 |  |  |
Fit filter B(z)/A(z)to the complex frequency response H at frequency points F. A and B are real polynomial coefficients of order nA and nB.
[B,A,C] = invfreqz(H,F,nB,nA,W,iter,tol,trace) [B,A,C] = invfreqz(H,F,nB,nA,W) [B,A,C] = invfreqz(H,F,nB,nA)
desired complex frequency response.
frequency (must be same length as H).
order of the numerator polynomial B.
order of the denominator polynomial A.
vector of weights (must be same length as F).
This is an Octave function. Fit filter B(z)/A(z)to the complex frequency response H at frequency points F. A and B are real polynomial coefficients of order nA and nB. Optionally, the fit-errors can be weighted vs frequency according to the weights W. Note: all the guts are in invfreq.m
[B,A] = butter(4,1/4); [H,F] = freqz(B,A); [Bh,Ah,C] = invfreq(H,F,4,4) Bh = 0.010209 0.040838 0.061257 0.040838 0.010209 Ah = 1.00000 -1.96843 1.73586 -0.72447 0.12039 C = -7.7065e-15 | | |