Hi Stan people,
I am new to Stan and would like to know if it is possible to fit a Noncentral chi-squared distribution. I did no find any information about it so I guess it is not implemented.
However the density of this distribution can be expressed with a formula containing the Confluent hypergeometric function 0F1. But I am not able to find how to call this function in stan code.
I know that stan uses the C++ library “boost” which contains the desired function hypergeometric_0F1.
Could anyone tell me if it possible to call this function in Stan otherwise I will try to find an other method to fit my data ?