The Excel GAMMALN Function

Related Functions:
GAMMA
GAMMADIST
GAMMALN and GAMMALN.PRECISE Functions

In Excel 2010, the Gammaln function has been replaced by the Gammaln.Precise function, which has improved accuracy.

Although it has been replaced, the Gammaln function is still available in Excel 2010 (stored in the list of compatibility functions), to allow compatibility with earlier versions of Excel.

Basic Description

The Excel Gammaln function returns the natural logarithm of the Gamma Function, Γ(n).

The syntax of the function is:

GAMMALN( x )

where x is the positive value at which you want to evaluate the function.


Gammaln Function Example

Chart of the Natural Logarithm of the Gamma Function
Natural Logarithm of the Gamma Function

The above chart on the right shows the natural logarithm of the Gamma Function.

If you want to calculate the value of this function at x = 4.5, this can be done using the Excel Gammaln function, as follows:

=GAMMALN( 4.5 )

This gives the result 2.453736571.


Further details and examples of the Excel Gammaln function are provided on the Microsoft Office website.


Gammaln Function Errors

If you get an error from the Excel Gammaln function this is likely to be one of the following:

Common Errors
#NUM!-Occurs if the supplied value of x is ≤ 0.
#VALUE!-Occurs if the supplied value of x is non-numeric.