igamma {dsdp}

Incomplete Gamma Function

Description

Evaluate an incomplete gamma function:

\gamma(a, x) = \int_{0}^{x} t^{a-1} e^{-t}dt,

using SLATEC dgami in https://netlib.org/slatec/. When (x > 0 and a \ge 0) or (x \ge 0 and a > 0), compute the result, otherwise the value is NaN.

Usage

igamma(a, x)

Arguments

a

A positive numeric vector.

x

A nonnegative numeric vector with same length as a. length.

Value

A vector of values of an incomplete gamma function.

See Also

igammac()

Examples

igamma(1, 1)