fast arc tangent routine available?

[Doug Gwyn]

In article <6002 at pt.cs.cmu.edu> aki at speech1.cs.cmu.edu (Yoshiaki Ohshima) writes:
>Hello, does anyone know if there are any 'arc tangent' routines, which run
>faster than atan() and atan2() of the standard C math library?

The library versions should be close to optimum.  The ones I know of are
pretty fast.

>I am now using Micro-Vax-II and (occasionally) PMAX, and have an impression
>that my simple-minded table lookup using bisection search doesn't seem to
>work well. Has anyone ever worked on this?

This is simply a numerical analysis question.  If you're not near 0, then
the atan curve is rather flat and a bisection search will not work well.
Why are you searching?