WorksheetFunction.Gamma_Dist Method

Returns the gamma distribution. You can use this function to study variables that may have a skewed distribution. The gamma distribution is commonly used in queuing analysis.

Namespace:  Microsoft.Office.Interop.Excel
Assembly:  Microsoft.Office.Interop.Excel (in Microsoft.Office.Interop.Excel.dll)

Syntax

'Declaration
Function Gamma_Dist ( _
    Arg1 As Double, _
    Arg2 As Double, _
    Arg3 As Double, _
    Arg4 As Boolean _
) As Double
'Usage
Dim instance As WorksheetFunction
Dim Arg1 As Double
Dim Arg2 As Double
Dim Arg3 As Double
Dim Arg4 As Boolean
Dim returnValue As Double

returnValue = instance.Gamma_Dist(Arg1, _
    Arg2, Arg3, Arg4)

double Gamma_Dist(
    double Arg1,
    double Arg2,
    double Arg3,
    bool Arg4
)

Parameters

• Arg1
  Type: System.Double

  X - the value at which you want to evaluate the distribution.

• Arg2
  Type: System.Double

  Alpha - a parameter to the distribution.

• Arg3
  Type: System.Double

  Beta - a parameter to the distribution. If beta = 1, Gamma_Dist returns the standard gamma distribution.

• Arg4
  Type: System.Boolean

  Cumulative - a logical value that determines the form of the function. If cumulative is true, Gamma_Dist returns the cumulative distribution function; if false, it returns the probability density function.

Return Value

Type: System.Double

Remarks

If x, alpha, or beta is nonnumeric, Gamma_Dist returns the #VALUE! error value.

If x < 0, Gamma_Dist returns the #NUM! error value.

If alpha ≤ 0 or if beta ≤ 0, Gamma_Dist returns the #NUM! error value.

The equation for the gamma probability density function is:

Figure 1: Gamma probability density function

The standard gamma probability density function is:

Figure 2: Standard gamma probability density function

When alpha = 1, Gamma_Dist returns the exponential distribution with:

Figure 3: Equation

For a positive integer n, when alpha = n/2, beta = 2, and cumulative = true, Gamma_Dist returns (1 - CHIDIST(x)) with n degrees of freedom.

When alpha is a positive integer, Gamma_Dist is also known as the Erlang distribution.

See Also

Reference

WorksheetFunction Interface

WorksheetFunction Members

Microsoft.Office.Interop.Excel Namespace