Re: Another damn simplifying problem: ArcTan
- To: mathgroup at smc.vnet.net
- Subject: [mg59945] Re: Another damn simplifying problem: ArcTan
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Fri, 26 Aug 2005 04:53:34 -0400 (EDT)
- Organization: The Open University, Milton Keynes, U.K.
- References: <dek7hq$a2t$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Mathieu McPhie wrote:
> Can someone please explain this to me: (M v4.something)
>
> In:= Simplify[ArcTan[-x]+ArcTan[x]]
> Out= 0
>
> In:= Simplify[ArcTan[-x,1]+ArcTan[x,1]]
> Out= ArcTan[-x,1]+ArcTan[x,1]
>
> Note, I want something more complicated than this obviously. Actually
> want something like
>
> Simplify[ArcTan[-x,y]+ArcTan[x,y]]
>
> but above is the easiest example of this infuriating programs problem.
>
> Cheers, Mathieu
>
Hi Mathieu,
What value do you expect? Zero in all cases?
In[1]:=
Simplify[ArcTan[-x, y] + ArcTan[x, y] /. {x -> I^2, y -> 1}]
Out[1]=
Pi
In[2]:=
Simplify[ArcTan[-x, y] + ArcTan[x, y] /. {x -> I^2, y -> -1}]
Out[2]=
-Pi
Regards,
/J.M.