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function [n, Wc] = cheb1ord(Wp, Ws, Rp, Rs)
//This function computes the minimum filter order of a Chebyshev type I filter with the desired response characteristics.
//Calling Sequence
//n = cheb1ord(Wp, Ws, Rp, Rs)
//[n, Wc] = cheb1ord(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 value
//Rs: real value
//Description
//This is an Octave function.
//This function computes the minimum filter order of a Chebyshev type I 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
//cheb1ord(0.1,0.2,-0.3,4)
//ans = 2
rhs = argn(2)
lhs = argn(1)
if(rhs~=4)
error("Wrong number of input arguments.")
end
select(lhs)
case 1 then
n = callOctave("cheb1ord",Wp,Ws,Rp,Rs)
case 2 then
[n,Wc] = callOctave("cheb1ord",Wp,Ws,Rp,Rs)
end
endfunction
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