Re: Re: Simplifying ArcTan

*To*: mathgroup at smc.vnet.net*Subject*: [mg55554] Re: [mg55541] Re: [mg55526] Simplifying ArcTan*From*: "David Park" <djmp at earthlink.net>*Date*: Tue, 29 Mar 2005 03:42:37 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

I don't know what I was thinking! It should be without the condition on x. But why shouldn't FullSimplify[ArcTan[Cos[x], Sin[x]], -Pi < x <= Pi] simplify to x? After all, the two argument ArcTan works for all combinations of arguments, except ArcTan[0, 0] and even that gives Interval[{-Pi, Pi}]. ArcTan[0, 3] Pi/2 In fact, why shouldn't it simplify to x just by specifying that x is Real? David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ From: Florian Jaccard [mailto:florian.jaccard at he-arc.ch] To: mathgroup at smc.vnet.net It does ! But you have to avoid 2 mistakes : 1) The brackets on wrong place 2) x may not be Pi/2 In[4]:= FullSimplify[ArcTan[Cos[x], Sin[x]], x >= 0 && x < Pi/2] Out[4]= x -----Message d'origine----- De : fizzy [mailto:fizzycist at knology.net] Envoyé : lun., 28. mars 2005 09:42 À : mathgroup at smc.vnet.net Objet : [mg55526] Simplifying ArcTan Why does FullSimplify[ ArcTan[ Cos[x], Sin[x] , x>=0 && x <= Pi/2 ] not output x ? Thanks...jerry blimbaum