Purpose
Returns the hyperbolic arc tangent of an arithmetic expression. 
Parameters
x is a floating-point value such that -1 < x < 1. 
Examples
ATANH(0.5)   /* returns 0.54930 */
Restrictions
An ATANH operation on floating-point decimal data is actually performed using the floating-point binary operation. Thus, the range of the operands and the result of the operation are limited to the ranges for floating-point binary numbers. 
 
Description
The ATANH(x) function returns the hyperbolic arc tangent of x. The result has the same data type as x.