Likelihood for Poisson distributed data
loglikelihood_cstat(obs, model_rate, exp_time = 1)
Arguments
- obs
observed counts
- model_rate
predicted count rates based on the current model
- exp_time
exposure tim
see https://heasarc.gsfc.nasa.gov/xanadu/xspec/manual/XSappendixStatistics.html
Value
Stirling's approximation, numeric