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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Inferring array index type from array object
Date: Wed, 30 Jun 2010 06:01:57 +0100
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Date: 2010-06-30T06:01:57+01:00
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Adam Beneschan <adam@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!