## ATANH intrinsic function

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

### ＜Syntax＞

ATANH ( 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 tangent 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 lie in the range −1<X<+1 (the result is infinite if ABS(X)==1, and NaN if ABS(X)>1). If X is of type Complex, the imaginary part of the result is in radians, in the range −π/2≤AIMAG(ATANH(X))≤π/2.