Syntax: @ATANH(X)
X = a numeric value between -1 and 1
@ATANH returns the hyperbolic arc tangent of angle X. The result is the angle (in radians) whose hyperbolic tangent is X.
Examples:
@ATANH(0) = 0
@ATANH(J20) = 1.127029, where J20 = 0.81
@ATANH(1) = Error - @ATANH, domain is -1 < x < 1