The Excel Gamma.Inv function returns the inverse of the Gamma Cumulative Distribution.
The function is new in Excel 2010 and so is not available in earlier versions of Excel. However, the Gamma.Inv function is simply a new version of the Gammainv function, which is available in earlier versions of Excel.
The syntax of the Gamma.Inv function is:
where the function arguments are:
|probability||-||The probability value (between 0 and 1), for which you want to calculate the inverse of the Gamma Cumulative Distribution Function.|
|alpha||-||A parameter of the distribution.|
|beta||-||beta=0, this specifies the inverse of the Standard Gamma Distribution).(Note: if|
The charts below show the Gamma Cumulative Distribution and the Inverse Gamma Cumulative Distribution, with the parameters alpha = 3 and beta = 2.
Gamma Cumulative Distribution Function with α=3 & β=2
Inverse Gamma Cumulative Distribution with α=3 & β=2
which gives the result 5.348120627.
For further examples of the Excel Gamma.Inv function, see the Microsoft Office website.
If you get an error from the Excel Gamma.Inv function this is likely to be one of the following:
|#N/A||-||Occurs if Excel fails to converge to a solution after 64 iterations.|
|#VALUE!||-||Occurs if any of the supplied arguments is non-numeric.|