ASIN (The GNU Fortran Compiler)

### 8.20 `ASIN` — Arcsine function ¶

Synopsis:

  `RESULT = ASIN(X)`

Description:

  `ASIN(X)` computes the arcsine of its X (inverse of `SIN(X)`).

Class:

  Elemental function

Arguments:

  X | The type shall be either `REAL` and a magnitude that is less than or equal to one - or be `COMPLEX`.

Return value:

  The return value is of the same type and kind as X. The real part of the result is in radians and lies in the range -\pi/2 \leq \Re \asin(x) \leq \pi/2.

Example:

      program test_asin
        real(8) :: x = 0.866_8
        x = asin(x)
      end program test_asin

Specific names:

  Name | Argument | Return type | Standard
  --- | --- | --- | ---
  `ASIN(X)` | `REAL(4) X` | `REAL(4)` | Fortran 77 and later
  `DASIN(X)` | `REAL(8) X` | `REAL(8)` | Fortran 77 and later

Standard:

  Fortran 77 and later, for a complex argument Fortran 2008 or later

See also:

  Inverse function:
  `SIN` — Sine function
  Degrees function:
  `ASIND` — Arcsine function, degrees