CODEWITHSUNDEEP
matlab3dfft
Marco Jammajalla Mangraviti
Marco Jammajalla Mangraviti

Reputation: 159

how to execute 3D-fft in matlab?

I have to transform an input column of 1024 complex value with 3D-fft in matlab. Dimensions are: Nx = 32 Ny = 16 Nz = 2.

What can I do?

Upvotes: 0

Views: 6071

Answers (1)

rayryeng
rayryeng

Reputation: 104514

You have two options:

Option #1 - Apply FFT in each dimension separately

You can manually apply the FFT in each dimension separately. Luis Mendo pointed out that the FFT is a separate operation. You can use the fft function to help you do that. Given that your signal is stored in A, do something like this:

B = fft(fft(fft(A, [], 1), [], 2), [], 3);

Because the operation is separable, it doesn't matter which order you apply the fft to. Here, I did it over the columns, then rows, then slices.

Option #2 - Use fftn

Alternatively, you can use fftn which does the above for you under the hood. This is the N-Dimensional FFT and the documentation says that the equivalent code that fftn performs under the hood is:

Y = X;
for p = 1:length(size(X))
    Y = fft(Y,[],p);
end

Take note that the above code is essentially doing what Option #1 is doing, but we did this without any loops and nested called fft three times.

Now, the above code assumes that your signal is stored in X.... so:

Y = fftn(X);

.... is what you'd do.

Upvotes: 3

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