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Re: Fourier Transform Graph Coordinates

  • To: mathgroup at smc.vnet.net
  • Subject: [mg95053] Re: Fourier Transform Graph Coordinates
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Sun, 4 Jan 2009 07:34:43 -0500 (EST)
  • References: <gjng7r$2mm$1@smc.vnet.net>

Hi,

what is with

lst=MapIndexed[{#2[[1]], #1} & ,
  Abs[Fourier[{-1, -1, -1, -1, 1, 1, 1, 1}]]]

Grid[Prepend[lst, {"X", "Y"}]]

??

Regards
   Jens

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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