afdxnai.m

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

function X = afdxnai(n,a,i)

% afdxnai.m  AFD i-th zero X(n,ksi,i) of elliptic rational function
%
% 2:32  15/2/99
%
%   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

X = ellipj( ((2*i-1)/n + 1)*ellipke(1/a^2), 1/a^2);

if abs(n-2*fix(n/2)) == 1
  if i == (n+1)/2;
    X = 0;
  end
end