### 8.155 `LOG_GAMMA` — Logarithm of the Gamma function

Description:
  `LOG_GAMMA(X)` computes the natural logarithm of the absolute value of the Gamma (\Gamma) function.
Standard:
  Fortran 2008 and later
Class:
  Elemental function
Syntax:
  `X = LOG_GAMMA(X)`
Arguments:

  X | Shall be of type `REAL` and neither zero nor a negative integer.

Return value:
  The return value is of type `REAL` of the same kind as X.
Example:

                program test_log_gamma
                  real :: x = 1.0
                  x = lgamma(x) ! returns 0.0
                end program test_log_gamma

Specific names:

  Name | Argument | Return type | Standard
  `LGAMMA(X)` | `REAL(4) X` | `REAL(4)` | GNU Extension
  `ALGAMA(X)` | `REAL(4) X` | `REAL(4)` | GNU Extension
  `DLGAMA(X)` | `REAL(8) X` | `REAL(8)` | GNU Extension

See also:
  Gamma function: GAMMA