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

ellip

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

Function Synopsis

[num, den, z, p] = ellip(n, Rp, Rs, Wn, ftype, anaflag)

Help text

ELLIP	Elliptic or Cauer digital and analog filter design.
	[B,A] = ELLIP(N,Rp,Rs,Wn) designs an N'th order lowpass digital
	elliptic filter with Rp decibels of ripple in the passband and
	a stopband Rs decibels down.  ELLIP returns the filter
	coefficients in length N+1 vectors B and A.  The cut-off
	frequency Wn must be 0.0 < Wn < 1.0, with 1.0 corresponding to
	half the sample rate.  Use Rp = 0.5 and Rs = 20 as starting
	points, if you are unsure about choosing them.

	If Wn is a two-element vector, Wn = [W1 W2], ELLIP returns an 
	order 2N bandpass filter with passband  W1 < W < W2.
	[B,A] = ELLIP(N,Rp,Rs,Wn,'high') designs a highpass filter.
	[B,A] = ELLIP(N,Rp,Rs,Wn,'stop') is a bandstop filter if Wn = [W1 W2].

	When used with three left-hand arguments, as in
	[Z,P,K] = ELLIP(...), the zeros and poles are returned in
	length N column vectors Z and P, and the gain in scalar K. 

	When used with four left-hand arguments, as in
	[A,B,C,D] = ELLIP(...), state-space matrices are returned. 

	ELLIP(N,Rp,Rs,Wn,'s'), ELLIP(N,Rp,Rs,Wn,'high','s') and 
	ELLIP(N,Rp,Rs,Wn,'stop','s') design analog elliptic filters.  
	In this case, Wn can be bigger than 1.0.

	See also ELLIPORD, CHEBY2, BUTTER, BESSELF, FREQZ and FILTER.

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