       Re: Integration - another Integer as a result

• To: mathgroup at smc.vnet.net
• Subject: [mg93784] Re: [mg93743] Integration - another Integer as a result
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Tue, 25 Nov 2008 07:20:50 -0500 (EST)
• Reply-to: hanlonr at cox.net

This integral evaluates on versions 5.2, 6.0.3, and 7 under Mac OS

Integrate[2 x Sin[n Pi x / l] Sin[k Pi x / l], x]

(l*((l*Cos[((k - n)*Pi*x)/l] +
(k - n)*Pi*x*Sin[((k - n)*Pi*x)/l])/
(k - n)^2 -
(l*Cos[((k + n)*Pi*x)/l] +
(k + n)*Pi*x*Sin[((k + n)*Pi*x)/l])/
(k + n)^2))/Pi^2

\$Version

7.0 for Mac OS X x86 (64-bit) (November 11, 2008)

Integrate[2 x Sin[n Pi x / l] Sin[k Pi x / l], x]

(l*((Pi*x*(k - n)*Sin[
(Pi*x*(k - n))/l] +
l*Cos[(Pi*x*(k - n))/l])/
(k - n)^2 -
(Pi*x*(k + n)*Sin[
(Pi*x*(k + n))/l] +
l*Cos[(Pi*x*(k + n))/l])/
(k + n)^2))/Pi^2

Bob Hanlon

---- MikeSw <sowasowa at o2.pl> wrote:

=============
Hello,

I'm trying to calculate an integer using Mathematica, but instead of getting a "normal" result I get another Integer. The algorithm available on Wolfram website does this calculation with no problem:

http://img156.imageshack.us/my.php?image=cakaqt6.jpg

but Mathematica gives this:

http://img156.imageshack.us/my.php?image=cakamtkmvk9.jpg

I guess there is something wrong with the input?

--

Bob Hanlon

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