ArcTan[1/0] no result, but ArcTan[Infinity] ok. How to resolve?

*To*: mathgroup at smc.vnet.net*Subject*: [mg56878] ArcTan[1/0] no result, but ArcTan[Infinity] ok. How to resolve?*From*: "steve" <nma124 at hotmail.com>*Date*: Mon, 9 May 2005 01:45:59 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

hi; Mathematica 5.1, on windows. ArcTan[1/0] gives an error but ArcTan[Infinity] gives the correct answer. One way to make ArcTan[1/0] give Pi/2 is to write it as ArcTan[0,1]. I do know that 1/0 is DirectedInfinity[] with unknown direction while Infinity is DirectedInfinity[1], and that is probably the reason that ArcTan[1/0] gives an error but ArcTan[Infinity] does not. I am asking is how to make 1/0 result in DirectedInfinity[1] to avoid the error? is this possible? What function do I need to wrap 1/0 with to cause it to become Infinity[1] instead of Infinity[] ? or may be I need to figure how to detect if a division results in Infinity[] and convert that to Infinity[1]? do I need to redfine 1/0 somehow? may be make a new rule to say if Mathematica see 1/0 expression then make it Infinity[1]? but may be this will screw other things? Or may I should not mess with this stuff and just change the code to ArcTan[x,y] instead of ArcTan[y/x] and be happy? thanks, Steve

**Follow-Ups**:**Re: ArcTan[1/0] no result, but ArcTan[Infinity] ok. How to resolve?***From:*Chris Chiasson <chris.chiasson@gmail.com>