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function h = freqs (b, a, w)
//Compute the s-plane frequency response of the IIR filter.
//Calling Sequence
//h = freqs (b, a, w)
//Parameters
//b: vector containing the coefficients of the numerator of the filter.
//a: vector containing the coefficients of the denominator of the filter.
//w: vector containing frequencies
//Description
//This is an Octave function.
//It computes the s-plane frequency response of the IIR filter B(s)/A(s) as H = polyval(B,j*W)./polyval(A,j*W).
//If called with no output argument, a plot of magnitude and phase are displayed.
//Examples
//B = [1 2];
//A = [1 1];
//w = linspace(0,4,128);
//freqs(B,A,w);
funcprot(0);
rhs = argn(2)
if(rhs<3 | rhs>3)
error("Wrong number of input arguments.")
end
select (rhs)
case 3 then
h = callOctave("freqs",b, a, w)
end
endfunction
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