如果楼主想在R实现LSTGARCH(1,1,1)
可设transition variable : et(t-1)
smoothness parameter :gamma
logistic function : 1/(1+exp(gamma*et(t-1))-1/2
依文献 Smooth-Transition GARCH Models page-75
S & P 500 7420 daily returns
Mean: y(t)=mu+rho*y(t-1)+et
Variance: var(t)=omega+alpha1*et(t-1)^2+alpha2*et(t-1)^2*
(1/(1+exp(gamma*et(t-1))-1/2)+beta*var(t-1)
利用nlminb()constrained optimization作出如下结果:
$par
[1] 0.021684340 0.174133551 0.002931679 0.068566567
0.081965011 0.932222533 33.383529233
$objective
[1] 8370.315
$iterations
[1] 54
系数估计结果,与作者相接近.