[Master Index] [Index for /tools/hpmatlab/toolbox/signal]

invfreqz

(/tools/hpmatlab/toolbox/signal/invfreqz.m)

Function Synopsis

[b,a]=invfreqz(g,w,nb,na,wf,maxiter,tol,pf)

Help text

INVFREQZ  Discrete filter least squares fit to frequency response data.

	[B,A] = INVFREQZ(H,W,NB,NA) gives real numerator and denominator 
	coefficients B and A of orders NB and NA respectively, where
	H is the desired complex frequency response of the system at frequency
	points W, and W contains the frequency values in radians/s.

	[B,A]=INVFREQZ(H,W,NB,NA,Wt) allows the fit-errors to the weighted
	versus frequency.  LENGTH(Wt)=LENGTH(W)=LENGTH(H).
	Determined by minimization of sum |B-H*A|^2*Wt over the freqs in W.

	[B,A] = INVFREQZ(H,W,NB,NA,Wt,ITER) does another type of fit:
	Sum |B/A-H|^2*Wt is minimized with respect to the coefficients in B and
	A by numerical search in at most ITER iterations.  The A-polynomial is 
	then constrained to be stable.  [B,A]=INVFREQZ(H,W,NB,NA,Wt,ITER,TOL)
	stops the iterations when the norm of the gradient is less than TOL.
	The default value of TOL is 0.01.  The default value of Wt is all ones.
	This default value is also obtained by Wt=[].

	[B,A]=INVFREQZ(H,W,NB,NA,Wt,ITER,TOL,'trace') will provide a textual
	progress report of the iteration.

	See also FREQZ, FREQS, and INVFREQS.

Cross-Reference Information

This function calls
Produced by mat2html on Wed Feb 8 12:25:18 EST 1995
Cross-Directory links are: ON