Complex arg-trig functions

[Stephen Montgomery-Smith]

On 09/16/2012 03:29 PM, Bruce Evans wrote:

> I'm thinking of going the other way and using atan(y/x) instead of atan2()
> :-).  This is safe iff we know that y/x is not very special.

This was, in fact, how it was presented in the original paper.  The 
Boost libraries also used atan instead of atan2.

In fact, when I first heard of the "atan2" function (perhaps way back 
when PL/1 was a programming language), I naively thought that atan(x) 
was implemented as atan2(1,x).