Syntax

C#
public static double Gamma( double x )

Visual Basic (Declaration)
Public Shared Function Gamma ( _ x As Double _ ) As Double

Visual C++
public: static double Gamma( double x )

Parameters

x: Type: System..::.Double
A double value.

Return Value

A double value specifying the Gamma function of x. If x is a negative integer, the result is NaN.

Remarks

The Gamma function, $\Gamma (x)$ , is defined to be

$\Gamma \left( x \right) = \int_0^\infty {t^{x - 1} } e^{ - t} dt \,\,\,\, for \, x \gt 0$

For $x \lt 0$ , the above definition is extended by analytic continuation.

The Gamma function is not defined for integers less than or equal to zero. Also, the argument x must be greater than so that $\Gamma (x)$ does not underflow, and x must be less than 171.64 so that $\Gamma (x)$ does not overflow. The underflow limit occurs first for arguments that are close to large negative half integers. Even though other arguments away from these half integers may yield machine-representable values of $\Gamma (x)$ , such arguments are considered illegal. Users who need such values should use the Log Gamma. Finally, the argument should not be so close to a negative integer that the result is less accurate than half precision.

$Plot of Gamma(x)$

Syntax

Parameters

Return Value

Remarks

See Also