## ACOSH intrinsic function

### Standard: F77 F90 F95 F2003 F2008 Example program

### ＜Syntax＞

ACOSH ( X )

X : Real or Complex;

Result : Same type and kind as X.

### ＜Semantics＞

The value of the result is an approximation to the arc hyperbolic cosine of X.
Like many intrinsic functions, this is **elemental**; the result has the same shape as X, with the operation being applied elementwise.

If X is of type Real, it must be greater than or equal to 1. If X is of type Complex, the imaginary part of the result is in radians, in the range 0.0≤AIMAG(ACOSH(X))≤π.