Compute the log-likelihood for a STAR model. The code here assumes
that the transformed real-valued process (z_star) has conditionally independent
components with means mu and standard deviations sigma.
logLikeRcpp(g_a_j, g_a_jp1, mu, sigma)loglike scalar log-likelihood value
m x 1 vector of g(a(j))
m x 1 vector of g(a(j + 1))
m x 1 vector of conditional expectations
m x 1 vector of conditional standard deviations