Apple iWork '09 - Manual (Page 260)

GAMMAINV
The GAMMAINV function returns the inverse gamma cumulative distribution.
GAMMAINV(probability, alpha, beta)
 probability: A probability associated with the distribution. probability is a number
value and must be greater than 0 and less than 1.
 alpha: One of the shape parameters of the distribution. alpha is a number value
and must be greater than 0.
 beta: One of the shape parameters of the distribution. beta is a number value and
must be greater than 0.
Examples
=GAMMAINV(0.8, 1, 2) returns 3.2188758248682.
=GAMMAINV(0.8, 2, 1) returns 2.99430834700212.
Related Topics
For related functions and additional information, see:
“GAMMADIST” on page 259
“GAMMALN” on page 260
“Listing of Statistical Functions” on page 225
“Value Types” on page 36
“The Elements of Formulas” on page 15
“Using the Keyboard and Mouse to Create and Edit Formulas” on page 26
“Pasting from Examples in Help” on page 41
GAMMALN
The GAMMALN function returns the natural logarithm of the gamma function, G(x).
GAMMALN(pos-x-value)
 pos-x-value: The positive x value at which you want to evaluate the function. pos-x-
value is a number value and must be greater than 0.
Examples
=GAMMALN(0.92) returns 0.051658003497744.
=GAMMALN(0.29) returns 1.13144836880416.
260 Chapter 10 Statistical Functions