low_mu_el.m

信号处理－滤波器设计（基于matlab和Mathmatica的设计方法）中关于无乘法器椭圆IIR滤波器设计的原创程序。

function L=Low_Mu_eL(n,e)
%  Low_Mu_L.m  已知e，求L
%  $date 4/10/2005
%
%   作者：赵泽平
%      [e-mail]
%   
%
%   References:
%        Miroslav D. Lutovac, Dejan V. Tosic, Brian L. Evans
%           Advanced Filter Design for Signal Processing
%                   Using MATLAB and Mathematica
if e>=sqrt(2)
    t=(1-(1-1/e^2)^0.25)/(2*(1+(1-1/e^2)^0.25));
    q=t+2*t^5+15*t^9+150*t^13;
else
    t=(1-1/e^0.5)/(2*(1+1/e^0.5));
    qp=t+2*t^5+15*t^9+150*t^13;
    q=exp(pi^2/log(qp));
end
L=0.25*sqrt(1/q^n-1);