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scipy.special.gammaincc

scipy.special.gammaincc(a, x) = <ufunc 'gammaincc'>

Regularized upper incomplete gamma function.

Defined as

$$\frac{1}{\Gamma(a)} \int_x^\infty t^{a - 1}e^{-t} dt$$

for $a > 0$ and $x \geq 0$. The function satisfies the relation gammainc(a, x) + gammaincc(a, x) = 1 where gammainc is the regularized lower incomplete gamma function.

See also

gammainc

regularized lower incomplete gamma function

gammaincinv

inverse to gammainc versus x

gammainccinv

inverse to gammaincc versus x

Notes

The implementation largely follows that of [R422].

References

[R422]

(1, 2) Maddock et. al., “Incomplete Gamma Functions”, http://www.boost.org/doc/libs/1_61_0/libs/math/doc/html/math_toolkit/sf_gamma/igamma.html