这个函数computes Sarma multiplicative（p，q）或X（p，q）模型的

代码说明：

This functions computes SARMA or multiplicative (p,q) x (P,Q) models for (p,q,P,Q) in (pvec x qvec x Pvec x Qvec) it returns the best according to AIC where AIC has been modified to account for fixed parameters x = input data pvec = vector of p s set pvec=[0] for no AR qvec = vector of q s set qvec=0[] for no MA Pvec = vector of P s Qvec = vector of Q s T period for multiplicative model -This functions computes SARMA or multiplicative (p,q) x (P,Q) models for (p,q,P,Q) in (pvec x qvec x Pvec x Qvec) it returns the best according to AIC where AIC has been modified to account for fixed parameters x = input data pvec = vector of p s set pvec=[0] for no AR qvec = vector of q s set qvec=0[] for no MA Pvec = vector of P s Qvec = vector of Q s T period for multiplicative model