arctanhreturns the value of the inverse hyperbolic tangent, .
For full information please refer to the NAG Library document for s11aa
The argument of the function.
The value of the inverse hyperbolic tangent, .
- (errno )
On entry, .
The function has been called with an argument greater than or equal to in magnitude, for which is not defined.
arctanhcalculates an approximate value for the inverse hyperbolic tangent of its argument, .
For it is based on the Chebyshev expansion
where , , .
For , it uses
For , the function fails as is undefined.
NIST Digital Library of Mathematical Functions