minor bug in cmath.asin?

[Tim Peters]

[Edwin Young]
> ...
> Does anyone know the history of the cmath implementation? There are
> some interesting formulas used for some of the trig functions and I'm
> curious to know where they came from.

You can browse the entire CVS history of any part of Python online at
SourceForge.  What that won't tell you in this case is that Guido originally
checked in the module as contributed by a scientist, who copied the formulas
out of some forgotten book -- and it wasn't a book about numerical analysis.
IOW, the formulas were numerically naive.  A few of those have been improved
over time, but nobody has cared enough about this module to maintain it
seriously.