Re: Strange "not a symbol or valid symbol name" error

*To*: mathgroup at smc.vnet.net*Subject*: [mg60238] Re: Strange "not a symbol or valid symbol name" error*From*: "Kevin J. McCann" <kmccann at umbc.edu>*Date*: Thu, 8 Sep 2005 04:53:19 -0400 (EDT)*Organization*: University of Maryland, Baltimore County*References*: <dfm86d$hek$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

I tried this and Mathematica does not find a closed form answer, but will do it numerically. I am not sure about your error, unless you have defined x previously. Try x=. before you integrate to see if this is the problem. Kevin Flip wrote: > Greetings all, I'm using Mathematica 5.0 and have been getting a > strange error message: > > Unique::usym : > 10000000000 is not a symbol or a valid symbol name > > This comes from the following integral: > > Integrate[E^(-x) Sqrt[x^2-9], {x,3,5}] > > The limits of integration don't matter much so long as they keep the > integrand real. > > I don't understand this and am not quite sure how to fix the problem. > (It's a well defined definite integral, right? It's real in the domain > of integration and nondivergent.) > > Thanks, > Flip >