phi_nk_three.m

一种新的光纤通信调制技术

function y = Phi_nk_three(alpha, beta, s) 
%%%%% \phi_nk(s) 的三阶导数

a=alpha(:);
b=beta(:);
I=ones(size(a));
[n1 , m1] =size (a) ;
[n2 , m2] =size(b) ;
if (m1~=1) | (m2~=1),
    error('x and nu must be vectors') ;
end ;
if(n1~=n2)
    error('x and nu must be of the same length');
end ;
if(s==0) 
    s = eps;
end

%%

 y = sum( ( 6*a.*b.^2+(2*b.^3).*(I-b*s) )./( (I-b*s).^4 ) )  - 2/(s.^3);

if(s>0)
	ds =  - 2/(s.^3);
else
	ds =   2/(s.^3);
end

%% y = sum( ( 6*a.*b.^2+(2*b.^3).*(I-b*s) )./( (I-b*s).^4 ) )  + ds;

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