eqiir

Arguments

ftype

filter type ('lp','hp','sb','bp')

approx

design approximation ('butt','cheb1','cheb2','ellip')

om

4-vector of cutoff frequencies (in radians) om=[om1,om2,om3,om4], 0 <= om1 <= om2 <= om3 <= om4 <= pi .When ftype='lp' or 'hp', om3 and om4 are not used and may be set to 0.

deltap

ripple in the passband. 0<= deltap <=1

deltas

ripple in the stopband. 0<= deltas <=1

cells

realization of the filter as second order cells

fact

normalization constant

zzeros

zeros in the z-domain

zpoles

poles in the z-domain

Description

Design of iir filter based on syredi.

The filter obtained is h(z)=fact*product of the elements of cells.

That is hz=fact*prod(cells.num)./prod(cells.den).

Examples

[cells,fact,zzeros,zpoles]=eqiir('lp','ellip',[2*%pi/10,4*%pi/10],0.02,0.001)
h=fact*poly(zzeros,'z')/poly(zpoles,'z')

See also

• eqfir — minimax approximation of FIR filter
• iir — iir digital filter
• syredi — Design of iir filters, syredi code interface