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Assuming and Integrate

• To: mathgroup at smc.vnet.net
• Subject: [mg128320] Assuming and Integrate
• From: hamiltoncycle at gmail.com
• Date: Sat, 6 Oct 2012 01:53:12 -0400 (EDT)
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When I try the line below in Mathematica 8 I get the answer 0 which is what I expect when m and n are different but not when m=n. Can anyone explain how to do this correctly?

Assuming[Element[{n, m}, Integers], Integrate[Sin[n*x]*Sin[m*x], {x, 0, Pi}]]

When m=n we should get Pi/2, as in this case:

Assuming[Element[n, Integers], Integrate[Sin[n*x]*Sin[n*x], {x, 0, Pi}]] 

cheers, Robert

• Follow-Ups:
  • Re: Assuming and Integrate
    • From: Murray Eisenberg <murray@math.umass.edu>
  • Re: Assuming and Integrate
    • From: Bob Hanlon <hanlonr357@gmail.com>