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Graph Fourier Transform

• To: mathgroup at smc.vnet.net
• Subject: [mg78901] Graph Fourier Transform
• From: efifer at fas.harvard.edu
• Date: Thu, 12 Jul 2007 05:21:02 -0400 (EDT)

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

• Follow-Ups:
  • Re: Graph Fourier Transform
    • From: Sseziwa Mukasa <mukasa@jeol.com>