IDAX.PGAMMA - Cumulative gamma distribution

The PGAMMA function returns the probability that the value of a variable that follows the gamma distribution is smaller or equal to x.

Syntax

IDAX.PGAMMA(DOUBLE x, DOUBLE shape, DOUBLE scaleInv)

Parameter descriptions

x
Mandatory.
The value that is to be computed.
Min: 0.000000001
Data type: DOUBLE
shape
Mandatory.
The shape of the distribution.
If shape is 0 or less, PGAMMA(x,shape,scaleInv) is null for all x values.
Min: 0.00000000001
Data type: DOUBLE
scaleInv
Mandatory.
The inverted scale of the distribution.
If scaleInv is 0 or less, PGAMMA(x,shape,scaleInv) is null for all x values.
Min: 0.00000000001
Data type: DOUBLE
PGAMMA(x,1,scaleInv) = PEXP(x,1/scaleInv) for all x values and positive scaleInv values.

Returned information

DOUBLE the cumulative probability distribution from minus infinity to point x.