# ACOS

Elemental Intrinsic Function (Generic): Produces the arccosine of x.

result = ACOS (x)

x | (Input) Must be of type real, where | x | must be less than or equal to 1, or of type complex.

## Results

The result type and kind are the same as x and is expressed in radians.

If the result is real, the value is expressed in radians and lies in the range 0 <= ACOS(X) <= pi.

If the result is complex, the real part is expressed in radians and lies in the range 0 <= REAL(ACOS (x)) <= pi.

Specific Name | Argument Type | Result Type
--- | --- | ---
ACOS 1 | REAL(4) | REAL(4)
DACOS 1 | REAL(8) | REAL(8)
QACOS 2 | REAL(16) | REAL(16)
1The setting of compiler options specifying real size can affect ACOS and DACOS. 2Or QARCOS.

## Example

ACOS (0.68032123) has the value .8225955.

Parent topic: A to B