afdsnaei.m

AFD - Advanced Filter Design using MATLABMiroslav D. Lutovac, Dejan V. Tosicversion 1.00 released 15

function Si = afdsnaei(n,a,e,i)

% afdsnaei.m  AFD i-th pole S(n,ksi,epsilon,i) of
%             normalized elliptic lowpass transfer function
%
% 2:35  16/2/99
%
%   Authors: Dejan V. Tosic, Miroslav D. Lutovac, 1999.02.08
%                 [e-mail]
%                 [e-mail]
%
%   Copyright (c) 1999 by Tosic & Lutovac
%   $Revision: 1.0 $  $Date: 1999/02/08 03:07:42 $
%
%   References:
%        Miroslav D. Lutovac, Dejan V. Tosic, Brian L. Evans
%           Advanced Filter Design for Signal Processing
%                   Using MATLAB and Mathematica

%  calls:
%% afdxnai.m, afdzeta.m

I = sqrt(-1);
x = afdxnai(n,a,i);
z = afdzeta(n,a,e);
numre = -z*sqrt(1 - z^2) * sqrt(1 - x^2) * sqrt(1 - x^2/a^2);
numim = x * sqrt(1 - (1-1/a^2)*z^2);
num = numre + I*numim;
den = 1 - (1 - x^2/a^2)*z^2;
Si= num/den;