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// Copyright (C) 2018 - IIT Bombay - FOSSEE
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
// Author:Sonu Sharma, RGIT Mumbai
// Organization: FOSSEE, IIT Bombay
// Email: toolbox@scilab.in
function [z, p, g] = cheb1ap (n, Rp)
//This function designs a lowpass analog Chebyshev type I filter.
//Calling Sequence
//[z, p, g] = cheb1ap (n, Rp)
//Parameters
//n: Filter Order
//Rp: Peak-to-peak passband ripple (in dB)
//z: Zeros
//p: Poles
//g: Gain
//Description
//It gives a lowpass analog Chebyshev type I filter of nth order and with a Peak-to-peak passband ripple of Rp.
//Examples
//[z, p, g] = cheb1ap (10, 3)
//Output :
// g =
//
// 0.0019578
// p =
//
// - 0.0138320 - 0.9915418i
// - 0.0401419 - 0.8944827i
// - 0.0625225 - 0.7098655i
// - 0.0787829 - 0.4557617i
// - 0.0873316 - 0.1570448i
// - 0.0873316 + 0.1570448i
// - 0.0787829 + 0.4557617i
// - 0.0625225 + 0.7098655i
// - 0.0401419 + 0.8944827i
// - 0.0138320 + 0.9915418i
// z =
//
// []
funcprot(0);
lhs = argn(1)
rhs = argn(2)
if (rhs < 2 | rhs > 2)
error("cheb1ap: Wrong number of input arguments.")
end
Rpf = 10 ^ (-Rp/20); //passband pick to pick ripple in fraction
rp = 1 - Rpf ; //analpf function compitable passband ripple (delta-p)
[hs,p,z,g]=analpf(n,"cheb1",[rp 0],1); //cutoff frequency of 1 rad/sec for prototype filter
p = p' ;
z = z' ;
g = abs(g);
endfunction
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