Re: Re: FourierTransform of Sinc Function

• To: mathgroup at smc.vnet.net
• Subject: [mg44413] Re: Re: FourierTransform of Sinc Function
• From: "Steve Luttrell" <luttrell at _removemefirst_westmal.demon.co.uk>
• Date: Sat, 8 Nov 2003 04:50:55 -0500 (EST)
• References: <200310281053.FAA25777@smc.vnet.net> <bo7of6\$ag8\$1@smc.vnet.net> <200311051500.KAA26329@smc.vnet.net> <bofrs7\$5gt\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```The top hat is centred on zero frequency. The default behaviour of Fourier
is for the zero freqency bin to be the first element of the list, so when
you plot this out the top hat is split between the left and right hand ends
of the graph.

--
Steve Luttrell
West Malvern, UK

"Kieng" <Sorasak at brown.edu> wrote in message
news:bofrs7\$5gt\$1 at smc.vnet.net...
> I am sorry my question is apparently not so clear.
> I generated a list of data from a sinc function.  I am not doing the
> transform from the sinc function.
> If I use Fourier[list of the data], and plot the result, her is where I am
> kind of not sure why I don't get a top hat function, even though I used
very
> fine step for my sinc function data.
>
> ----- Original Message -----
> From: "Jens-Peer Kuska" <kuska at informatik.uni-leipzig.de>
To: mathgroup at smc.vnet.net
> Subject: [mg44413]  Re: FourierTransform of Sinc Function
>
>
> > Hi,
> >
> > what is mysterious on
> >
> > In[]:=FourierTransform[Sin[w*x]/x, x, k]
> >
> > Out[]=(Sqrt[Pi/2]*(-Sign[k - w] + Sign[k + w]))/2
> >
> > Regards
> >   Jens
> >
> > Kieng wrote:
> > >
> > > Dear All,
> > >
> > >  I tested the Fourier Function on a sinc function which should give
the
> > > top-hat but mathatmatica gave some mysterious plot that I don't
> understand.
> > > Anyone knows what is going on.
> > >
> > > Thank you very much,
> > > Sorasak
> >
>

```

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