Re: Very strange behaviour of ArcTan[]

*To*: mathgroup at smc.vnet.net*Subject*: [mg102666] Re: Very strange behaviour of ArcTan[]*From*: Pillsy <pillsbury at gmail.com>*Date*: Tue, 18 Aug 2009 06:07:42 -0400 (EDT)*References*: <h6bh4m$6ov$1@smc.vnet.net>

On Aug 17, 8:06 am, Alexey <lehi... at gmail.com> wrote: > I just have discovered some strange (buggy?) feature of ArcTan[] > function in Mathematica 5.2. Try the following; What you've discovered is that ArcTan has a definition for two arguments where ArcTan[x, y] gives you ArcTan[y/x], but correctly accounting for the signs of x and y. This is actually a pretty common bit of functionality to have access to; in the C standard library there's a two-argument function called atan2 that does the same thing, for instance. Cheers, Pillsy