# gamma

The gamma function.

## Calling Sequence

    y = gamma(x)

## Arguments

x

  real vector or matrix

y

  real vector or matrix with same size than x.

## Description

`gamma(x)` evaluates the gamma function at all the elements of `x`. The gamma function is defined by :

and generalizes the factorial function for real numbers (`gamma(n+1) = n!`).

## Examples

    // simple examples
    gamma(0.5)
    gamma(6)-prod(1:5)

    // the graph of the Gamma function on [a,b]
    a = -3; b = 5;
    x = linspace(a,b,40000)';
    y = gamma(x);
    clf()
    c=xget("color")
    xset("color",2)
    plot2d(x, y, style=0, axesflag=5, rect=[a, -10, b, 10])
    xset("color",c)
    xtitle("The gamma function on ["+string(a)+","+string(b)+"]")
    show_window()

a = -3; b = 5; x = linspace(a,b,40000)'; y = gamma(x); plot2d(x, y, style=0, axesflag=5, rect=[a, -10, b, 10]) xtitle("The gamma function on ["+string(a)+","+string(b)+"]")

## See Also

- gammaln
- dlgamma

## History

5.4.0
Overloading allowed for list, mlist, tlist and hypermatrix types.