Re: Inferring array index type from array object

[Adam Beneschan <adam@irvine.com>]

On Jun 29, 10:01 pm, Simon Wright <si...@pushface.org> wrote:
> Adam Beneschan <a...@irvine.com> writes:
> > By the way, I'm not sure that the error is the main reason for having
> > this function.  The result of the two-argument arctan function is in
> > the range -pi .. +pi, as opposed to -pi/2 .. +pi/2 for the one-
> > argument variation; this allows you to get a result in any of the four
> > quadrants (instead of just two), giving you the correct result when
> > you want to compute the angle corresponding to a point (x, y) on a
> > Cartesian graph.
>
> And avoiding problems with the extremes; arctan (y / x) is a Bad Idea!

I assume you mean because x could be 0.0 (or close to it)?  Yes,
that's another case where the two-argument arctan will give you the
result you probably want (i.e. +pi/2 or -pi/2).

                           -- Adam