Arccosine (inverse cosine) function.

**X**- must be of type real with a value that satisfies the inequality |X| <= 1.

**Class**

Elemental function

**Result Type and Attributes**

Same as X.

**Result Value**

- It is expressed in radians, and approximates arccos(X).
- It is in the range 0 <= ACOS(X) <= &pi..

**Examples**

ACOS (1.0) has the value 0.0.

Specific Name | Argument Type | Result Type | Pass As Arg? |
---|---|---|---|

ACOS | default real | default real | yes |

DACOS | double precision real | double precision real | yes |

QACOS (1)
| REAL(16) | REAL(16) | yes |

QARCOS (1)
| REAL(16) | REAL(16) | yes |

**Notes: **

- IBM Extension.