LOG_GAMMA intrinsic function
Standard: F77 F90 F95 F2003 F2008 Example Program

X : Real;

Result : Same type and kind as X.

The value of X shall not be a negative integer or zero.
The value of the result is an approximation to the natural log of the absolute value of the gamma function of X. The gamma function is the extension of factorial from the integers to the reals, so that when X is a positive integer, LOG_GAMMA(X) is an approximation to LOG((X−1)!). Like many intrinsic functions, this is elemental; the result has the same shape as X, with the operation being applied elementwise.

The logarithm operation prevents overflow except for very large values of X.

ABS intrinsic function, GAMMA intrinsic function, LOG intrinsic function.