Re: wrong limit ?

*To*: mathgroup at smc.vnet.net*Subject*: [mg76795] Re: [mg76734] wrong limit ?*From*: DrMajorBob <drmajorbob at bigfoot.com>*Date*: Sun, 27 May 2007 05:04:32 -0400 (EDT)*References*: <7513700.1180172543602.JavaMail.root@m35>*Reply-to*: drmajorbob at bigfoot.com

First of all, I suspect you meant Limit[Coth[x B], B -> +Infinity] not Limit[Coth[xB], B -> +Infinity] There's a very big difference. Secondly, the limit doesn't exist for ANY non-zero B, since Limit[Coth[x], x -> -Infinity] -1 Limit[Coth[x], x -> Infinity] 1 and letting x approach +/- 1/B Infinity makes x B approach +/- Infinity = = (on the real line). Bobby On Sat, 26 May 2007 03:43:44 -0500, ventu <nuclearVentu at gmail.com> wrote= : > Hi ! > Here's my problem (mathematica 5.0,5.1,5.2): > > Limit[Coth[xB], B -> +Infinity] > > it doesn't understand. > mmh. ok I try then: > > Limit[Coth[x B], B -> +Infinity, Assumptions -> Im[x] == 0] > > 1 > > WRONG ! In fact: > > Limit[Coth[x B], B -> +Infinity, Assumptions -> Im[x] == 0 && Re[= x] < > 0] > > -1 > > Indeed the correct result should be sign(x). And I couldn't find a way= > to get it right. > Do I mistake something? > > Thank you in advance, > > Davide > > > -- = DrMajorBob at bigfoot.com