Calculate the Normalizing Constant in log scale for COM-Poisson distribution The calculation of the function logZ will be performed here. This function is used to approximate the normalizing constant for COM-Poisson distributions via truncation. The standard COM-Poisson parametrization is being used here.

It is assumed that vectors log_lambda & nu are of equal length.

logZ_c(log_lambda, nu, summax)

Arguments

log_lambda

rate parameter in log scale.

nu

dispersion parameter, straightly positive.

summax

maximum number of terms to be considered in the truncated sum.

Details

This function was originally purposed in the cmpreg package of Ribeiro Jr, Zeviani & Demétrio (2019).

References

Ribeiro Jr, E. E., Zeviani, W. M., Demétrio, C. G. B. (2019) cmpreg: Reparametrized COM-Poisson Regression Models. R package version 0.0.1.