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analpf Scilab Group Scilab Function analpf
NAME
analpf - create analog low-pass filter
CALLING SEQUENCE
[hs,pols,zers,gain]=analpf(n,fdesign,rp,omega)
PARAMETERS
n : positive integer : filter order
fdesign : string : filter design method : 'butt' or 'cheb1' or 'cheb2'
or 'ellip'
rp : 2-vector of error values for cheb1, cheb2 and ellip filters
where only rp(1) is used for cheb1 case, only rp(2) is used for
cheb2 case, and rp(1) and rp(2) are both used for ellip case.
0<rp(1),rp(2)<1
- for cheb1 filters 1-rp(1)<ripple<1 in passband
- for cheb2 filters 0<ripple<rp(2) in stopband
- for ellip filters 1-rp(1)<ripple<1 in passband
0<ripple<rp(2) in stopband
omega : cut-off frequency of low-pass filter in Hertz
hs : rational polynomial transfer function
pols : poles of transfer function
zers : zeros of transfer function
gain : gain of transfer function
DESCRIPTION
Creates analog low-pass filter with cut-off frequency at omega.
hs=gain*poly(zers,'s')/poly(pols,'s')
EXAMPLE
//Evaluate magnitude response of continuous-time system
hs=analpf(4,'cheb1',[.1 0],5)
fr=0:.1:15;
hf=freq(hs(2),hs(3),%i*fr);
hm=abs(hf);
plot(fr,hm)
AUTHOR
C. B.
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