dyj26201 发表于 2018-10-8 20:54
楼主可以发一份正确的garch代码不,最近也在琢磨matlab里估计garch函数的源代码,实在是头疼呐,好长好长。 ...
function [logl] = GARCH(parameter,r)
%-----------------GARCH model-----------------------
% E[r(t)]=0
% r(t)=h(t)^0.5*randn(1)
% h(t)=omega+alpha*r(t-1)^2+beta*h(t-1)
%___________________________________________________
omega=parameter(1);
alpha=parameter(2);
beta=parameter(3);
T=length(r);
h=zeros(T,1);
% t= 1
h(1)=sum(r.^2)/T;
% t=2 to T
for k=2:T
h(k)=omega+alpha*r(k-1)^2+beta*h(k-1);
end
logl=-(T/2)*log(2*pi)-sum(log(sqrt(h)))-0.5*sum(r.^2./h);
logl=-logl;
end