Re: Documentation fix regarding atan2

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: a(dot)maclean(at)cas(dot)edu(dot)au
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Documentation fix regarding atan2
Date: 2007-09-14 15:54:02
Message-ID: 200709141554.l8EFs2G21618@momjian.us
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Change made. Thanks. Your documentation changes can be viewed in five
minutes using links on the developer's page,
http://www.postgresql.org/developer/testing.

---------------------------------------------------------------------------

Andrew Maclean wrote:
> In Table 9.4 of the documentation atan2 is described as follows:
> atan2(*x*, *y*) inverse tangent of *x*/*y*
>
> I am sure it should read as:
> atan2(*y*, x) inverse tangent of y/x
>
> This looks to be the standard C++/c atan2(y,x) function.
>
> You can easily test this:
> If y = 2, x = 1, then degrees(atan(y/x)) =63.4 but if we proceed according
> to the documentation; degrees(atan2(x,y))=degrees(atan2(1,2))=25.6 which is
> not the same as degrees(atan(y/x)).
> So it must be degrees(atan2(y,x))=degrees(atan2(2,1))=63.4.
>
>
> Thanks
> Andrew
>
> --
> ___________________________________________
> Andrew J. P. Maclean
> Centre for Autonomous Systems
> The Rose Street Building J04
> The University of Sydney 2006 NSW
> AUSTRALIA
> Ph: +61 2 9351 3283
> Fax: +61 2 9351 7474
> URL: http://www.acfr.usyd.edu.au/
> ___________________________________________

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://www.enterprisedb.com

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