Re: Integrating Abs[Sin[]^2]
- To: mathgroup at smc.vnet.net
- Subject: [mg38880] Re: Integrating Abs[Sin[]^2]
- From: "David W. Cantrell" <DWCantrell at sigmaxi.org>
- Date: Fri, 17 Jan 2003 05:38:37 -0500 (EST)
- References: <b032m9$mv4$1@smc.vnet.net> <b05r8a$2b6$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Marian Otremba <marianUSUN at zeus.polsl.gliwice.pl> wrote:
> Jos R Bergervoet wrote:
> >
> > A strange result appeared when using
> >
> > Mathematica 4.1 for Linux
> > Copyright 1988-2000 Wolfram Research, Inc.
> > -- Motif graphics initialized --
> >
> > in computing the following:
> >
> > result = Integrate[ Abs[Sin[k x]]^2, {x,0,1}]
> > N[ result /. k->I+1 ]
> >
> > (* Analytical approach gives 0.261044 + 0.616283 I, WRONG !!! *)
>
> In[1]:= result = Integrate[ Abs[Sin[k x]]^2, {x,0,1},
> Assumption->{Im[k]>0}] (* !! *)
> N[ result /. k->I+1 ]
> Out[2]:= 0.67391
Strange. That doesn't work for me (using version 4.2 for Windows).
I did exactly what you said (except with "Assumptions" instead of
"Assumption") yet got the complex result reported by JRB.
David