The Excel Gammaln function returns the natural logarithm of the Gamma Distribution.
Syntax: GAMMALN( x )
where x is the positive value at which you want to evaluate the function.
Gammaln Function Example
The chart on the right shows the natural logarithm of the Gamma Distribution. If you want to calculate the value of this function at x = 4.5, this can be done by the Excel Gammaln function, as follows:
=GAMMALN( 4.5 )
This gives the result 2.453736571.
Gammaln Function Errors
If you get an error from the Excel Gammaln function this is likely to be one of the following :
|#NUM!||–||Occurs if the supplied value of x is ≤ 0|
|#VALUE!||–||Occurs if the supplied value of x is not recognised as a numeric value|