GAMMAINV

Syntax:

GAMMAINV ( probability , alpha , beta )

Description: Computes the inverse of the gamma distribution. Given a value for probability, GAMMAINV seeks that value x such that GAMMADIST(x, alpha, beta, TRUE) = probability. Thus, the precision of GAMMAINV depends on the precision of GAMMADIST. GAMMAINV uses an iterative search technique.

Arguments:

Name	Type	Description
probability	number	The probability associated with the gamma distribution.
alpha	number	A parameter of the distribution.
beta	number	A parameter of the distribution. If beta = 1, `GAMMAINV` returns the standard gamma distribution.

Return Type and Value: number – The inverse of the gamma distribution.

However, if

probability < 0 or probability > 1, #NUM! is returned.
alpha ≤ 0 or beta ≤ 0, #NUM! is returned.
The search has not converged after some implementation-defined number of iterations, #N/A is returned.

example: