SpecFunc_RegularizedIncompleteGamma

SpecFunc_RegularizedIncompleteGamma(a, x, tail=False)

Regularized incomplete Gamma function.

\forall x \in \Rset, \quad
\mathrm{P}(a, x) = \frac{\gamma(a, x)}{\Gamma(a)}
                 = \frac{1}{\Gamma(a)}\int_0^x t^{a-1}\exp(-t)\di{t}

Parameters:
a : float \in \Rset^*_+
x : float
tail : bool, optional

By default, tail is False.

Returns:
result : float
  • If tail is False: result = \mathrm{P}(a, x).
  • If tail is True: result = \Gamma(a) - \mathrm{P}(a, x).