dfdnell.m

来自「AFD - Advanced Filter Design using MATLA」· M 代码 · 共 22 行

function nellip = dfdnell(Fp,Fs,Kp,Ks)

% dfdnell.m  Minimum order of erf for a given spec
%
%   Authors: Dejan V. Tosic, Miroslav D. Lutovac, 1999.03.08
%                 [e-mail]
%                 [e-mail]
%
%   Copyright (c) 1999 by Tosic & Lutovac
%   $Revision: 1.0 $  $Date: 1999/03/08 03:07:42 $
%
%   References:
%        Miroslav D. Lutovac, Dejan V. Tosic, Brian L. Evans
%           Advanced Filter Design for Signal Processing
%                   Using MATLAB and Mathematica

k      = tan(pi*Fp)/tan(pi*Fs);
L      = Ks/Kp;
num    = ellipke(1-1/L^2)/ellipke(1/L^2);
den    = ellipke(1 - k^2)/ellipke(k^2);
nellip = ceil(num/den);