# gamma

Gamma function

## Syntax

`Y = gamma(X)`

## Definitions

The `gamma` function is defined by the integral:

$\Gamma \left(x\right)={\int }_{0}^{\infty }{e}^{-t}{t}^{x-1}dt$

The `gamma` function interpolates the `factorial` function. For integer `n`:

`gamma(n+1) = n! = prod(1:n)`

## Description

`Y = gamma(X)` returns the `gamma` function at the elements of `X`. `X` must be real.

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### Algorithms

The computation of `gamma` is based on algorithms outlined in [1]. Several different minimax rational approximations are used depending upon the value of `A`.

## References

[1] Cody, J., An Overview of Software Development for Special Functions, Lecture Notes in Mathematics, 506, Numerical Analysis Dundee, G. A. Watson (ed.), Springer Verlag, Berlin, 1976.

[2] Abramowitz, M. and I.A. Stegun, Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series #55, Dover Publications, 1965, sec. 6.5.