gammaInc

gammaInc (a, x [, upperTail ])

The gammaInc function returns the value of the incomplete gamma function, defined by the integral

$$\displaystyle \Gamma(a, x)=\int_{x}^{\infty} e^{-t} t^{a-1} d t.$$

If upperTail is zero, the limits of integration are 0 to x. If upperTail is absent, it defaults to 1, and the limits of integration are x to infinity, as shown. Note that gammaInc(a, x) = gamma(a) - gammaInc(a, x, 0).

Defined for x > 0, a >= 0 (upperTail = zero or absent) or a > 0 (upperTail = 0).

See Also

gamma, gammp, gammq