Re: Graph Fourier Transform
- To: mathgroup at smc.vnet.net
- Subject: [mg78930] Re: Graph Fourier Transform
- From: dh <dh at metrohm.ch>
- Date: Fri, 13 Jul 2007 05:59:42 -0400 (EDT)
- References: <f74sip$8ip$1@smc.vnet.net>
Hi Emily,
I do not fully understand what you try to achieve. If you have a
digitized sound sample, the way to go would be FFT, not continuos
Fourier transform. This is used if you have functions.
If you really want to plot Dirac functions, you may replace them by
something with a finite width, e.g. Fun[x_]:=If[Abs[x]<0.02,1,0]
hope this helps, Daniel
efifer at fas.harvard.edu wrote:
> Hi,
>
> I'd really appreciate some help on how I should graph a Fourier Transform of a
> sin function. I am trying to create a frequency spectra of a sound and have the
> input:
>
> FourierTransform[Sum[ampout[i]*Sin[(2.*3.14159*freq[i])t], {i, 1, 18}], t, ?]
>
> As I am trying to get the continuous Fourier Transform. However the answer this
> gives me is full of dirac deltas, which will plot to zero on a graph:
>
> Plot[FourierTransform[Sum[ampout[i]*Sin[(2.*3.14159*
> freq[i])t], {i, 1, 18}], t, 300], {t, 0, 40}, Axes -> True]
>
>
> Does anyone know how I can manipulate the data to get the major frequencies in
> the sound to show up as peaks on the graph?
>
> Thanks,
> Emily
>
>