Re: Why is Mathematica assuming k==l and how do I make it
- To: mathgroup at smc.vnet.net
- Subject: [mg92613] Re: [mg92588] Why is Mathematica assuming k==l and how do I make it
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Wed, 8 Oct 2008 06:25:34 -0400 (EDT)
- Reply-to: hanlonr at cox.net
Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi},
Assumptions -> {l == k, Element[{l, k}, Integers]}]
Pi
Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi},
Assumptions -> {l != k, Element[{l, k}, Integers]}]
0
Assuming[{l == k, Element[{k, l}, Integers]},
Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi}]]
Pi
Assuming[{l != k, Element[{k, l}, Integers]},
Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi}]]
0
Bob Hanlon
---- Aaron Fude <aaronfude at gmail.com> wrote:
=============
As in
Assuming[Element[{k, l}, Integers] ,
Integrate[Cos[k alpha] Cos[l alpha], {alpha, -Pi, Pi}]]
I get 0 whereas the answer is Pi if k=l;
Thanks!
Aaron
--
Bob Hanlon