Definition. This function returns the natural logarithm of the gamma function (Γ(x)).
Background. The GAMMALN() function returns the natural logarithm of the gamma function.
You will find more information about gamma distributions in the description of GAMMA.DIST().
The logarithm (to base b) of a number y is the number by which base b has to be raised to produce number y. Therefore, the logarithm is an exponent, and the logarithm function is the inverse function of the exponential function (see Figure 12-66).
GAMMALN() is calculated as follows:
Example. Assume that you want to calculate GAMMALN() given the value 4. Figure 12-67 shows the calculation of GAMMALN().
The GAMMALN() function returns the natural logarithm, 1.7918, for the gamma function based on the parameters shown in Figure 12-67.