Re: ArcTan[x, 0] With Numeric Values

*To*: mathgroup at smc.vnet.net*Subject*: [mg30561] Re: [mg30544] ArcTan[x, 0] With Numeric Values*From*: Andrzej Kozlowski <andrzej at tuins.ac.jp>*Date*: Wed, 29 Aug 2001 01:40:05 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

You seem to have discovered a (minor) bug, which causes Simplify to misbehave for certain specific numeric inputs: namely Pi or E (and maybe others) but not 2Pi, E/2 etc. For example: In[2]:= Simplify[{ArcTan[2Pi,0],ArcTan[Pi/2,0],ArcTan[E/2,0],ArcTan[E,0], ArcTan[Pi,0]}] Out[2]= {0, 0, 0, ArcTan[E, 0], ArcTan[Pi, 0]} Andrzej Kozlowski Toyama International University JAPAN http://platon.c.u-tokyo.ac.jp/andrzej/ On Tuesday, August 28, 2001, at 05:54 PM, David Park wrote: > Dear MathGroup, > > Why does this two argument form of ArcTan not automatically simplify > with > numeric input? It does simplify with number input. > > {ArcTan[5, 0], ArcTan[Sqrt[5], 0], ArcTan[Pi, 0]} > Simplify[%] > FullSimplify[%] > > {0, ArcTan[Sqrt[5], 0], ArcTan[Pi, 0]} > {0, 0, ArcTan[Pi, 0]} > {0, 0, 0} > > One would normally expect the same simplification to automatically > occur in > all three of these cases. > > David Park > djmp at earthlink.net > http://home.earthlink.net/~djmp/ > > >