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MathGroup Archive 2001

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Re: Bug in FourierTransform?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg31088] Re: Bug in FourierTransform?
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Tue, 9 Oct 2001 01:55:39 -0400 (EDT)
  • Organization: Universitaet Leipzig
  • References: <9pme6e$657$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Hi,

FourierTransform[] does not split sums into 
single terms. Because FourierTransform[a+b,_,_]
may extist but FourierTransform[a,_,_]+FourierTransform[b,_,_]
may be not existing or may be divergent.

I assume that Mathematica try to integrate the full
expression and this take a very long time.

Regards
  Jens

Daniel Arteaga wrote:
> 
> Hi,
> 
> Mathematica hangs up when trying to compute the Fourier transform of
> 
> F[X_, Y_] :=
>   E^(-100 + 20*X - 2*X^2 - 10*Y - Y^2/2) +
>     E^(-100 - 2*X^2 - 10*Y - Y^2/2 + 10*(10 + Y)) +
>     E^(-200 + 20*X - 2*X^2 - 10*Y - Y^2/2 + 10*(2*X + Y)) +
>     E^(-200 - 2*X^2 - 10*Y - Y^2/2 + 10*(10 + Y) + 10*(2*X + Y))
> 
> FourierTransform[F[X,Y],Y,P]
> 
> (keeps running forever)
> 
> However, it computes very fast the Fourier transform of each term
> separately. I am using Mathematica 4.1 in Windows 2000. Mathematica 2.2
> computed correctly this fourier transform.
> 
> Any idea?
> 
> Daniel Arteaga


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