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function [a, b, c, d] = ellip (n, rp, rs, w, varargin)
//This function generates an elliptic or Cauer filter with rp dB of passband ripple and rs dB of stopband attenuation.
//Calling Sequence
//[a, b] = ellip (n, rp, rs, wp)
//[a, b] = ellip (n, rp, rs, wp, "high")
//[a, b] = ellip (n, rp, rs, [wl, wh])
//[a, b] = ellip (n, rp, rs, [wl, wh], "stop")
//[a, b, c] = ellip (…)
//[a, b, c, d] = ellip (…)
//[…] = ellip (…, "s")
//Parameters
//n: positive integer value
//rp: non negative scalar value
//rs: non negative scalar value
//w: scalar or vector, all elements should be in the range [0,1]
//Description
//This is an Octave function.
//This function generates an elliptic or Cauer filter with rp dB of passband ripple and rs dB of stopband attenuation.
//[b, a] = ellip(n, Rp, Rs, Wp) indicates low pass filter with order n, Rp decibels of ripple in the passband and a stopband Rs decibels down and cutoff of pi*Wp radians. If the fifth argument is high, then the filter is a high pass filter.
//[b, a] = ellip(n, Rp, Rs, [Wl, Wh]) indictaes band pass filter with band pass edges pi*Wl and pi*Wh. If the fifth argument is stop, the filter is a band reject filter.
//[z, p, g] = ellip(...) returns filter as zero-pole-gain.
//[...] = ellip(...,’s’) returns a Laplace space filter, w can be larger than 1.
//[a, b, c, d] = ellip(...) returns state-space matrices.
//Examples
//[a,b]=ellip(2, 0.5, 0.7, [0.3,0.4])
//a =
// 0.88532 -1.58410 2.40380 -1.58410 0.88532
//b =
// 1.00000 -1.78065 2.68703 -1.75725 0.97454
rhs = argn(2)
lhs = argn(1)
if(rhs>3)
[rows,columns] = size(w)
end
if(rhs>6 | rhs<4)
error("Wrong number of input arguments.")
end
if(lhs>4 | lhs<2)
error("Wrong number of output arguments.")
end
select (rhs)
case 4 then
if (lhs==2) [a,b] = callOctave("ellip",n, rp, rs, w)
elseif (lhs==3) [a,b,c] = callOctave("ellip",n, rp, rs, w)
elseif (lhs==4) [a,b,c,d] = callOctave("ellip",n, rp, rs, w)
end
case 5 then
if (lhs==2) [a,b] = callOctave("ellip",n, rp, rs, w, varargin(1))
elseif (lhs==3) [a,b,c] = callOctave("ellip",n, rp, rs, w, varargin(1))
elseif (lhs==4) [a,b,c,d] = callOctave("ellip",n, rp, rs, w, varargin(1))
end
case 6 then
if (lhs==2) [a,b] = callOctave("ellip",n, rp, rs, w, varargin(1), varargin(2))
elseif (lhs==3) [a,b,c] = callOctave("ellip",n, rp, rs, w,varargin(1), varargin(2))
elseif (lhs==4) [a,b,c,d] = callOctave("ellip",n, rp, rs, w, varargin(1), varargin(2))
end
end
endfunction
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