WorksheetFunction.Gamma_Inv method (Excel)

Returns the inverse of the gamma cumulative distribution. If p = GAMMA_DIST(x,...), then GAMMA_INV(p,...) = x.

Syntax

expression.Gamma_Inv (Arg1, Arg2, Arg3)

expression A variable that represents a WorksheetFunction object.

Parameters

Name	Required/Optional	Data type	Description
Arg1	Required	Double	Probability - the probability associated with the gamma distribution.
Arg2	Required	Double	Alpha - a parameter to the distribution.
Arg3	Required	Double	Beta - a parameter to the distribution. If beta = 1, Gamma_Inv returns the standard gamma distribution.

Return value

Double

Remarks

Use this function to study a variable whose distribution may be skewed.

If any argument is text, Gamma_Inv returns the #VALUE! error value.

If probability < 0 or probability > 1, Gamma_Inv returns the #NUM! error value.

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

Given a value for probability, Gamma_Inv seeks that value x such that GAMMA_DIST(x, alpha, beta, TRUE) = probability. Thus, precision of Gamma_Inv depends on precision of Gamma_Dist. Gamma_Inv uses an iterative search technique. If the search has not converged after 100 iterations, the function returns the #N/A error value.

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