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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