# ACOSH

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

result = ACOSH (x)

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

## Results

The result type and kind are the same as x.

If the result is complex, the real part is non-negative, and the imaginary part is expressed in radians and lies in the range -pi <= AIMAG (ACOSH (x)) <= pi.

Specific Name | Argument Type | Result Type
--- | --- | ---
ACOSH 1 | REAL(4) | REAL(4)
DACOSH 1 | REAL(8) | REAL(8)
QACOSH | REAL(16) | REAL(16)
1The setting of compiler options specifying real size can affect ACOSH and DACOSH.

## Example

ACOSH (1.0) has the value 0.0.

ACOSH (180.0) has the value 5.8861.

Parent topic: A to B