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Student Support Forum: 'FourierTransform' topicStudent Support Forum > General > Archives > "FourierTransform"

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M.Belevich
01/30/08 05:57am

Hi,

I try to use the FourierTransform and its inverse and obtain strange results, e.g.

a = -0.5; b = 3.5; zero = 1.5;
FourierTransform[
If[x <= a || x >= b, 0., Exp[-Abs[x - zero]], x, k]
gives zero, but using Chop
FourierTransform[
If[x <= a || x >= b, 0., Exp[-Abs[x - zero]] //
Chop, x, k]
the right answer is obtained

1/((1.+ k^2) Sqrt[
2 \[Pi]]) \[ExponentialE]^(-0.5 \[ImaginaryI] k) (-0.135335 +
2. \[ExponentialE]^(2. \[ImaginaryI] k) + \[ExponentialE]^(
4. \[ImaginaryI] k) (-0.135335 - (0.+
0.135335 \[ImaginaryI]) k) + (0.+
0.135335 \[ImaginaryI]) k)

Why does Chop solve the problem? Some other examples may be found in the attached file

Attachment: Error.nb, URL: ,
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