pow function with exponent required to be integer
pow_int(a, b)
a^b
Base
Exponent
This is required in nimble models and nimbleFunctions if derivatives will be tracked but tracked only with respect to a, such that b might be any (positive, 0, or negative) integer. This contrasts with pow(a, b) (equivalent to a^b), which requires b > 0 if derivatives will be tracked, even if they will only be requested with respect to a.