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.TH eqiir 1 "April 1993" "Scilab Group" "Scilab Function"
.so ../sci.an
.SH NAME
eqiir - Design of iir filters
.SH CALLING SEQUENCE
.nf
[cells,fact,zzeros,zpoles]=eqiir(ftype,approx,om,deltap,deltas)
.fi
.SH PARAMETERS
.TP 10
ftype
: filter type (\fV'lp','hp','sb','bp'\fR)
.TP
approx
: design approximation (\fV'butt','cheb1','cheb2','ellip'\fR)
.TP
om
: 4-vector of cutoff frequencies (in radians)
\fVom=[om1,om2,om3,om4]\fR, \fV0 <= om1 <= om2 <= om3 <= om4 <= pi\fR.
When \fVftype\fR='lp' or 'hp', \fVom3\fR and \fVom4\fR are not used
and may be set to 0.
.TP
deltap
: ripple in the passband. \fV0<= deltap <=1\fR
.TP
deltas
: ripple in the stopband. \fV0<= deltas <=1\fR
.TP
cells
: realization of the filter as second order cells
.TP
fact
: normalization constant
.TP
zzeros
: zeros in the z-domain
.TP
zpoles
: poles in the z-domain
.SH DESCRIPTION
Design of iir filter interface with eqiir (syredi)
.LP
The filter obtained is \fVh(z)=fact\fR*product of the elements of
\fVcells\fR.
.LP
That is \fVhz=fact*prod(cells(2))./prod(cells(3))\fR
.SH EXAMPLE
.nf
[cells,fact,zzeros,zpoles]=...
eqiir('lp','ellip',[2*%pi/10,4*%pi/10],0.02,0.001)
transfer=fact*poly(zzeros,'z')/poly(zpoles,'z')
.fi
.SH SEE ALSO
eqfir, iir
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