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MathGroup Archive 1997

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Re: Fourier Help!!

  • To: mathgroup at smc.vnet.net
  • Subject: [mg6455] Re: [mg6434] Fourier Help!!
  • From: BobHanlon at aol.com
  • Date: Fri, 21 Mar 1997 23:00:03 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

$Version

Power Macintosh 2.2 (February 24, 1994)

?Fourier

Fourier[list] finds the discrete Fourier transform of a
   list of complex numbers.

Fourier[{-1, -1, -1, 1, 1, 1}]

Fourier[{-1, -1, -1, 1, 1, 1}]

Returns unevaluated because input is a list of integers.  Using reals:

Fourier[{-1., -1., -1., 1., 1., 1.}] // Chop

{0, -0.816497 - 1.41421 I, 0, -0.816497, 0, 
 
  -0.816497 + 1.41421 I}

InverseFourier[%] // Chop

{-1., -1., -1., 1., 1., 1.}

Alternatively,

Fourier[{-1, -1, -1, 1, 1, 1}] // N // Chop

{0, -0.816497 - 1.41421 I, 0, -0.816497, 0, 
 
  -0.816497 + 1.41421 I}

InverseFourier[%] // Chop

{-1., -1., -1., 1., 1., 1.}


Bob Hanlon


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