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

*To*: mathgroup at smc.vnet.net*Subject*: [mg56165] Re: [mg56120] Trouble with Limit[I ... k]/k, k-> Infinity]*From*: Chris Chiasson <chris.chiasson at gmail.com>*Date*: Sun, 17 Apr 2005 03:07:15 -0400 (EDT)*References*: <200504160751.DAA24601@smc.vnet.net>*Reply-to*: Chris Chiasson <chris.chiasson at gmail.com>*Sender*: owner-wri-mathgroup at wolfram.com

Set the $Assumptions variable so that Mathematica knows which expressions are real and non-zero. For example: I had some expressions describing a three (ideal) gas mixture. Mathematica could not integrate them until I had told it the domain of every variable in the integration *and* that the sum of every combination of two mol fractions was less than 1. 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 > > -- Chris Chiasson Kettering University Mechanical Engineering Graduate Student 1 810 265 3161

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