Gamma Command

Gamma( <Alpha>, <Beta>, <Variable Value> ): Calculates the value of the cumulative distribution function of a Gamma distribution at variable value v, i.e. the probability P(X ≤ v) where X is a random variable with a Gamma distribution defined by the parameters alpha and beta.

This syntax returns the probability at a given value, that is the area under the Gamma distribution curve to the left of the given x-coordinate.

Gamma( <Alpha>, <Beta>, <Variable Value>, <Boolean Cumulative> ): If Cumulative = true, calculates the value of the cumulative distribution function of a Gamma distribution with given alpha and beta at the given variable value, otherwise it calculates the probability density function of the distribution at variable value.
Gamma( <Alpha>, <Beta>, x, <Boolean Cumulative> ): If Cumulative = true, creates the cumulative density function (cdf) of a Gamma distribution with given alpha and beta, othewise it creates the probability density function (pdf) of the distribution.