GAMMA (The GNU Fortran Compiler)

### 8.125 `GAMMA` — Gamma function ¶

Synopsis:

  `X = GAMMA(X)`

Description:

  `GAMMA(X)` computes Gamma (\Gamma) of X. For positive, integer values of X the Gamma function simplifies to the factorial function \Gamma(x)=(x-1)!.

Class:

  Elemental function

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_gamma
        real :: x = 1.0
        x = gamma(x) ! returns 1.0
      end program test_gamma

Specific names:

  Name | Argument | Return type | Standard
  --- | --- | --- | ---
  `DGAMMA(X)` | `REAL(8) X` | `REAL(8)` | GNU extension

Standard:

  Fortran 2008 and later

See also:

  Logarithm of the Gamma function:
  `LOG_GAMMA` — Logarithm of the Gamma function