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Re: Definite integral

• To: mathgroup at smc.vnet.net
• Subject: [mg88468] Re: Definite integral
• From: Szabolcs Horvát <szhorvat at gmail.com>
• Date: Tue, 6 May 2008 06:39:04 -0400 (EDT)
• Organization: University of Bergen
• References: <fvmmrd$8ef$1@smc.vnet.net>

Miguel wrote:
> I don't understand Mathematica can't calculate the last definite
> integral. For the first three integrals works fine, but for the last
> one crush. You can see in this paper
> 
> http://mathematicaes.googlegroups.com/web/Curves.pdf?gda=7zTXujoAAAA-whg7foWysEERSilJsIeVif4THE-OC9pisLLDECe8l5BwmXXnNsFOempl8HAl8JkHsusoMR-tRlq_vv1lRgeh&gsc=CGn5gQsAAABmIpg7U95zHJwjbRxzLtsD

This is because you typed \[Epsilon] instead of \[Element].

This works fine:

Integrate[3/2 Sqrt[Sin[2 x]^2], {x, 3 Pi/2, t},
  Assumptions -> 2 Pi > t > (3 Pi)/2]

It is not necessary to separately specify that variables used in 
inequalities are reals.  But if you do, use x \[Element] Reals or 
Element[x, Reals], but *not* x \[Epsilon] Reals.  The two symbols have 
nothing to do with each other!

So this is one more reason why the ugly lunate epsilon should not be 
used in mathematics ...  I never understood why American/English 
textbooks were so fond of this symbol (never seen it in any Eastern 
European books).