gamma

Scilab Function
Last update : 06/07/2004

gamma - The gamma function.

### Calling Sequence

  `y = gamma(x)`

### Parameters

- `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 :

                         /+oo
                         |   x-1  -t
             gamma(x) =  |  t    e    dt
                         /0

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);
    xbasc()
    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)+"]")
    xselect()

### See Also

`gammaln` , `dlgamma` ,

### Author

W. J. Cody and L. Stoltz (code from Netlib (specfun))