       Re: Strange result for a definite integral: Unknown Symbol

• To: mathgroup at smc.vnet.net
• Subject: [mg81852] Re: [mg81825] Strange result for a definite integral: Unknown Symbol
• From: "W. Craig Carter" <ccarter at mit.edu>
• Date: Fri, 5 Oct 2007 04:45:03 -0400 (EDT)
• References: <200710040826.EAA21652@smc.vnet.net>

```I am still getting this strange result, but I now know what
\.10 is. It is the hexadecimal code 10 for a symbol. I don't
know how that is creeping into this result.

On Thu, 4 Oct 2007, W. Craig Carter wrote:

> To: mathgroup at smc.vnet.net
> Subject: [mg81825] Strange result for a definite integral: Unknown Symbol
>     (\.10) returned
>
>
> Hello, I am getting a result that I can't understand. An unknown symbol
> "\.10" is appearing.
>
> InputForm[integrand] is
> (R*(R - x*Cos[t] - y*Sin[t]))/(3*(R^2 + x^2 + y^2 + (z - zeta)^2 - 2*R*(x*Cos[t] + y*Sin[t]))^3)
>
> InputForm{assumptions] is
> {R > 0, L > 0, Element[zeta, Reals], Element[x, Reals], Element[y, Reals], Element[z, Reals]}
>
> integral = Integrate[integrand,{t,0,2 Pi}, Assumptions->assumptions]
>
> returns (after a longish evaluation, about 20 minutes on my  machine)
> InputForm[integral] is
> (2*\.10*R^2*(R^4 - 2*x^4 - 2*y^4 - y^2*z^2 + z^4 -
> x^2*(4*y^2 + (z - zeta)^2) + R^2*(x^2 + y^2 + 2*(z -
> zeta)^2) +
>    2*y^2*z*zeta - 4*z^3*zeta - y^2*zeta^2 + 6*z^2*zeta^2 -
> 4*z*zeta^3 + zeta^4)*
>   (Log[(-2*(R^2 + 2*R*x + x^2 + y^2 + z^2 - 2*z*zeta +
> zeta^2))/Sqrt[-R^4 + 2*R^2*(x^2 + y^2 - (z - zeta)^2) -
>        (x^2 + y^2 + (z - zeta)^2)^2]] - Log[(2*(R^2 + 2*R*x
> + x^2 + y^2 + z^2 - 2*z*zeta + zeta^2))/
>      Sqrt[-R^4 + 2*R^2*(x^2 + y^2 - (z - zeta)^2) - (x^2 +
> y^2 + (z - zeta)^2)^2]]))/
>  (3*(-R^4 + 2*R^2*(x^2 + y^2 - (z - zeta)^2) - (x^2 + y^2 +
> (z - zeta)^2)^2)^(5/2))
>
> (The \.10 appears as a little space, subsequent
> operations give me a tiny little space to a power)
>
>
> FullForm[integral] returns
> Times[Rational[2, 3], \.10, ....
>
> What is the symbol \.10 doing in there? What is it?
>
> I am using the 64-bit kernel on a macintosh intel chip dual core machine. Math 6.01
>
> Thanks, Craig
>
>

```

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