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

• To: mathgroup at smc.vnet.net
• Subject: [mg60218] Re: Strange "not a symbol or valid symbol name" error
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Thu, 8 Sep 2005 04:52:56 -0400 (EDT)
• Organization: The Open University, Milton Keynes, U.K.
• References: <dfm86d\$hek\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```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
>
First, clear the definition of any variables or quit the kernel, then
use *NIntegrate* since *Integrate* will not return any symbolic value
but the integrand itself.

In[1]:=
Clear["Global`*"];
Integrate[Sqrt[x^2 - 9]/E^x, {x, 3, 5}]

Out[2]=
Integrate[Sqrt[-9 + x^2]/E^x, {x, 3, 5}]

In[3]:=
NIntegrate[Sqrt[x^2 - 9]/E^x, {x, 3, 5}]

Out[3]=
0.08562828535776716

In[4]:=
\$Version

Out[4]=
"5.2 for Microsoft Windows (June 20, 2005)"

Regards,
/J.M.

```

• Prev by Date: Re: true limit of mathematica ? Help me !!!
• Next by Date: Re: true limit of mathematica ? Help me !!!
• Previous by thread: Re: Strange "not a symbol or valid symbol name" error
• Next by thread: Re: Strange "not a symbol or valid symbol name" error