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Re: Fourier Transform Graph Coordinates

  • To: mathgroup at smc.vnet.net
  • Subject: [mg95036] Re: [mg95022] Fourier Transform Graph Coordinates
  • From: Bob Hanlon <hanlonr at cox.net>
  • Date: Sun, 4 Jan 2009 07:31:30 -0500 (EST)
  • Reply-to: hanlonr at cox.net

data = Abs[Fourier[{-1, -1, -1, -1, 1, 1, 1, 1}]]

{0.,1.84776,0.,0.765367,0.,0.765367,0.,1.84776}

Prepend[Thread[{Range[Length[data]], data}],
   {"x", "y"}] // Grid

Prepend[Transpose[{Range[Length[data]], data}],
   {"x", "y"}] // Grid

p = ListLinePlot[data]

Prepend[p[[1, 1, 3, 2, 1]], {"x", "y"}] // Grid

Prepend[Cases[p, Line[{pts__}] :> pts,
    Infinity], {"x", "y"}] // Grid



Bob Hanlon


On Sat, Jan 3, 2009 at 9:03 AM , DAVID FOURIE wrote:

> Hi all,
>
> I am wanting to compare Fourier Transform graphs in a Java Program. 
> For thi=
> s I need the coordinates, or graph points of the created Fourier 
> Transform =
> graph.
>
> For example using the Mathematica example:
>
>         In[]:=  Fourier[{-1,-1,-1,-1,1,1,1,1}]
>         Out[]:= {0.\[InvisibleSpace] + 0. \[ImaginaryI], -0.707107 - 
> 1.70=
> 711 \[ImaginaryI], 0.\[InvisibleSpace] + 0. \[ImaginaryI], -0.707107 - 
> 0.29=
> 2893 \[ImaginaryI], 0.\[InvisibleSpace] + 0. [ImaginaryI], -0.707107 + 
> 0.29=
> 2893 \[ImaginaryI], 0.\[InvisibleSpace] + 0. \[ImaginaryI], -0.707107 
> + 1.7=
> 0711 \[ImaginaryI]}
>
>         In[]:=  ListPlot[Abs[Fourier[{-1, -1, -1, -1, 1, 1, 1, 1}]],
>         Out[]:= A zig zag graph.
>
>
> I want the coordinates of this graph. I have tried exporting it as a 
> table =
> but it is indecipherable. Idealy the graph would be in the style:
> X       Y
> 1       10
> 2       23
> 3       24
> 4       27
> 5       31
>
> Etc
>
> The style is not the concern though it is just getting the data which 
> gener=
> ates the graph.
>
> Yours
>
>
>
> David Fourie BSc Computer Science
> David.fourie at ncl.ac.uk
> MPhil Computational Neuroscience
> D809
> ext - 8593


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