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freqz

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

Function Synopsis

[hh,ff] = freqz(b,a,n,dum,Fs)

Help text

FREQZ	Z-transform digital filter frequency response.
	When N is an integer, [H,W] = FREQZ(B,A,N) returns the N-point frequency
	vector W in radians and the N-point complex frequency response vector H
	of the filter B/A:
	                            -1                -nb 
	     jw	 B(z)   b(1) + b(2)z + .... + b(nb+1)z
	  H(e) = ---- = ----------------------------
	                            -1                -na
	         A(z)    1   + a(2)z + .... + a(na+1)z
	given numerator and denominator coefficients in vectors B and A. The
	frequency response is evaluated at N points equally spaced around the
	upper half of the unit circle. If N isn't specified, it defaults to 512.

	[H,W] = FREQZ(B,A,N,'whole') uses N points around the whole unit circle.

	H = FREQZ(B,A,W) returns the frequency response at frequencies 
	designated in vector W, in radians (normally between 0 and pi).

	[H,F] = FREQZ(B,A,N,Fs) and [H,F] = FREQZ(B,A,N,'whole',Fs) given a 
	sampling freq Fs in Hz return a frequency vector F in Hz.
	
	H = FREQZ(B,A,F,Fs) given sampling frequency Fs in Hz returns the 
	complex frequency response at the frequencies designated in vector F,
	also in Hz.

	FREQZ(B,A,...) with no output arguments plots the magnitude and
	unwrapped phase of B/A in the current figure window.

	See also FILTER, FFT, INVFREQZ, FREQS and GRPDELAY.

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Produced by mat2html on Wed Feb 8 12:25:18 EST 1995
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