log_regularized_gamma_lower Function

public pure elemental function log_regularized_gamma_lower(a, x, max_iterations) result(rst)

Log lower gamma ratio; invalid inputs or nonconvergence return NaN.

Arguments

Type	Intent	Optional	Attributes		Name
real(kind=real64),	intent(in)			::	a	Finite, positive gamma shape parameter.
real(kind=real64),	intent(in)			::	x	Nonnegative integration limit; +infinity is accepted.
integer(kind=int32),	intent(in),	optional		::	max_iterations	Series/continued-fraction iteration limit; default 10000.

Return Value real(kind=real64)

Log P(a, x); x = 0 gives -infinity, x = +infinity gives zero.