From: | "Andrew Maclean" <andrew(dot)amaclean(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Documentation fix regarding atan2 |
Date: | 2007-09-05 00:37:18 |
Message-ID: | e7ddbec60709041737h56f7e385xf3c622ca7b407a2b@mail.gmail.com |
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Lists: | pgsql-general |
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/
___________________________________________
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