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`_()

See Also

• `gammaln`_ The logarithm of gamma function.
• `dlgamma`_ derivative of gammaln function, psi function

History

Version Description 5.4.0 Overloading allowed for list, mlist, tlist and hypermatrix types. .. _dlgamma: dlgamma.html .. _gammaln: gammaln.html