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Question on multiple variables FourierTransformation.


Dear Collegue,

I carry out Fourier Tranformation of second derivative of a function.

When the function is defined as u[x],
     FourierTransform[D[u[x],{x,2}],x,k]    ---->  -k^2
FourierTransform[u[x], x, k]

But if I introduce another variable and write the function as u[x,t],
carry out same transformation,

      FourierTransform[D[u[x,t],{x,2}],x,k]    gives me only
FourierTransform[u(2, 0)(x, t), x, k]    which is supposed to be
-k^2 FourierTransform[u[x,t], x, k]

I am wondering if Mathematica always defautly considers the variables
dependent so it cannt work out the Fourier transform with mutliple
variables.

Thanks for your help.

Weilou Gao

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Email: wxg124 at psu.edu
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