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Re: stange result with complex numbers

  • To: mathgroup at smc.vnet.net
  • Subject: [mg36266] Re: stange result with complex numbers
  • From: Tom Burton <tburton at brahea.com>
  • Date: Thu, 29 Aug 2002 01:37:49 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

On 8/28/02 1:24 AM, in article aki1kh$i9g$1 at smc.vnet.net, "Peter Nagy"
<pnagy at gwdg.de> wrote:

> I am having a strange problem with a function giving a complex number as
> a result...

You should perhaps examine the integral of denom. Do you really expect a
complex result? The integral involves multibranched functions (a fact masked
a bit by the form Tan[p] in the integrand; try replacing Tan[p] by p to see
what is going on). Is your result on the branch you want? I suspect not; you
are probably after a real result. The following modification produces a real
result: 

Integrate[denom[x, p, d], {x, 0, d}, PrincipalValue -> True,
GenerateConditions -> False]

But you'll need to take the limit p->0.

Hope this helps,

Tom Burton



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