Re: Trouble with Limit[I ... k]/k, k-> Infinity]

*To*: mathgroup at smc.vnet.net*Subject*: [mg56157] Re: [mg56120] Trouble with Limit[I ... k]/k, k-> Infinity]*From*: yehuda ben-shimol <bsyehuda at gmail.com>*Date*: Sun, 17 Apr 2005 03:07:01 -0400 (EDT)*References*: <200504160751.DAA24601@smc.vnet.net>*Reply-to*: yehuda ben-shimol <bsyehuda at gmail.com>*Sender*: owner-wri-mathgroup at wolfram.com

Hi, I'm quite surprised from your last comment since on my system (ver. 5.1, Win XP) Limit[Exp[I k]/k, k -> Infinity] returns 0 as expected. As for the first expression, I couldn't find a single expression covering both a>0 and a<0 but it works for both sub expressions separately Limit[Exp[I k a]/k, k -> Infinity, Assumptions -> a > 0] returns 0 and Limit[Exp[I k a]/k, k -> Infinity, Assumptions -> a < 0] returns 0 but both Limit[Exp[I k a]/k, k -> Infinity, Assumptions -> (a > 0 || a < 0)] and its equivalent Limit[Exp[I k a]/k, k -> Infinity, Assumptions -> (a !=0)] return a warning message and no result May be it will be a good idea to break the original expression into these two subexpressions? yehuda On 4/16/05, Christian Mikkelsen <s010132 at student.dtu.dk> wrote: > > I am struggling to valuate an intermediate result in a long calculation > and I get stuck with terms like this one: > > Limit[Exp[I k A]/k, k -> Infinity, Assumptions -> {A != 0, A \[Element] > Reals}] > > In the actual expression, A are somewhat more complicated expressions but > I am willing to tell Mathematica by hand that they are real and > non-zero, however, it still doesn't work. I don't see that there is a > problem in mathematical terms so how can I convince Mathematica to > give me an answer? > > Actually, Mathematica 5.1 does not mind telling me the result of > > Limit[Exp[I k]/k, k -> Infinity] > > At the moment I am relying on a kludge relying on pattern-matching but I > am not very good at it so there might be a point to help me on. > Any input or help will be greatly appreciated. > > Thanks, > > Christian > >

**References**:**Trouble with Limit[I ... k]/k, k-> Infinity]***From:*Christian Mikkelsen <s010132@student.dtu.dk>