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From: "saag" <saag37@yahoo.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada 95 ARCTAN function
Date: 1 Mar 2007 13:39:40 -0800
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thanks for the quick responses.
Didn't exactly phrase my question properly as I'm really interested in
whether the Ada arctan function returns a value based on the quadrant
-
and according to both that diagram & the link in the other post the
results in the range (-pi, pi) are what I was hoping for.

thanks again


On Mar 1, 2:43 pm, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:
> On 1 Mar 2007 10:58:25 -0800, saag wrote:
>
> > Does the ARCTAN(y,x) function in the ADA.NUMERICS package provide the
> > same results an atan2 function call in c?  I'm trying to find out if
> > Ada supplies an atan2 function (that gives an appropriate answer based
> > on the quadrant the original point lies in)
>
> A.5.1 (11) states that arctan (y, x) yields the result in the quadrant of
> the point (x,y). I.e. (with circle=2pi)
>
>        |    y>0    |    y<0
> -------+-----------+----------
> x>0    |  0..pi/2  | -pi/2..0
>        |           |
> x<0    |  pi/2..pi | -pi..-pi/2
>
> When x is negative and y is approaches 0 changing its sign, it gets
> instable (either pi or -pi). Argument_Error is propagated when x and y are
> 0.
>
> (I cannot tell how this corresponds to the semantics of atan2)
>
> --
> Regards,
> Dmitry A. Kazakovhttp://www.dmitry-kazakov.de