function [n, Wp] = ellipord(Wp, Ws, Rp, Rs)
//This function computes the minimum filter order of an elliptic filter with the desired response characteristics. 
//Calling Sequence
//[n] = ellipord(Wp, Ws, Rp, Rs)
//[n, Wp] = ellipord(Wp, Ws, Rp, Rs)
//Parameters 
//Wp: scalar or vector of length 2, all elements must be in the range [0,1] 
//Ws: scalar or vector of length 2, all elements must be in the range [0,1]
//Rp: real or complex value
//Rs: real or complex value
//Description
//This is an Octave function.
//This function computes the minimum filter order of an elliptic filter with the desired response characteristics. 
//Stopband frequency ws and passband frequency wp specify the the filter frequency band edges. 
//Frequencies are normalized to the Nyquist frequency in the range [0,1]. 
//Rp is measured in decibels and is the allowable passband ripple and Rs is also measured in decibels and is the minimum attenuation in the stop band.
//If ws>wp then the filter is a low pass filter. If wp>ws, then the filter is a high pass filter.
//If wp and ws are vectors of length 2, then the passband interval is defined by wp and the stopband interval is defined by ws. 
//If wp is contained within the lower and upper limits of ws, the filter is a band-pass filter. If ws is contained within the lower and upper limits of wp, the filter is a band-stop or band-reject filter.
//Examples
//[a,b]=ellipord(0.2, 0.5, 0.7, 0.4)
//a =  1
//b =  0.20000

rhs = argn(2)
lhs = argn(1)
if(rhs~=4)
error("Wrong number of input arguments.")
end
select(lhs)
case 1 then
n = callOctave("ellipord",Wp,Ws,Rp,Rs)
case 2 then
[n,Wp] = callOctave("ellipord",Wp,Ws,Rp,Rs)
end
endfunction