Mark Dickinson wrote:
> Sorry:  I should have read more carefully.  So math.atanh works on Linux 
> but is producing some strange results on Windows.
> 
> It's still rather puzzling though.  I still suspect that it's the 
> argument to log1p that's coming out wrong rather than the result.

It uses t = 0.5 * log1p((x + x) / (1.0 - x)) for t > 0.5. I presume the
culprit is in "2 / x" where x is almost 0. Do you have an idea how we
can increase the accuracy for values nearly 1.?

Christian