regularized_gamma_upper Function

public pure elemental function regularized_gamma_upper(a, x) result(rst)

Computes the regularized upper incomplete gamma function.

The regularized upper incomplete gamma function is defined as: $$Q(a, x) = \frac{\Gamma(a, x)}{\Gamma(a)} = 1 - P(a, x)$$

Remarks

Whichever of the series or the continued fraction converges rapidly is evaluated directly, such that the result retains its relative accuracy even when the probability is vanishingly small.

See Also

• Wikipedia

Arguments

Type	Intent	Optional	Attributes		Name
real(kind=real64),	intent(in)			::	a	The coefficient value. The value must be positive.
real(kind=real64),	intent(in)			::	x	The value at which to evaluate the function. The value must be non-negative.

Return Value real(kind=real64)

The function value, which lies on the interval [0, 1].