Investment Studio > Expressions > Functions > Statistical > GAMMAINV
float gammainv(float probability, float alpha, float beta)
Returns the inverse of the gammal CDF (Cumulative Distribution Function): if probability = gammadist(x, alpha, beta, TRUE), then gammainv(probability, alpha, beta) = x.
probability must be in the range [0, 1].
alpha and beta must be > 0.
The result is determined by an iterative procedure that terminates when the incremental improvement is less than 1E-10 per iteration. If this precision is not achieved after 10000 iterations, the result is an error (#N/A).
Example
=gammainv(0.0119045038561503, 8, 3)
returns 9.0000000001803.