Inverse complex FFTW transform

1. What is the inverse FFT?
2. What does FFTW really compute?
3. Is FFTW free?
4. Does Matlab use FFTW?

What is the inverse FFT?

Inverse Fast Fourier transform (IDFT) is an algorithm to undoes the process of DFT. It is also known as backward Fourier transform. It converts a space or time signal to a signal of the frequency domain.

What does FFTW really compute?

FFTW computes an unnormalized transform, that is, the equation IFFT(FFT(X)) = n X holds. In other words, applying the forward and then the backward transform will multiply the input by n. An FFTW_FORWARD transform corresponds to a sign of -1 in the exponent of the DFT.

Is FFTW free?

We believe that FFTW, which is free software, should become the FFT library of choice for most applications. The latest official release of FFTW is version 3.3. 10, available from our download page.

Does Matlab use FFTW?

In a MATLAB Function block, fftw is supported only for simulation. For C/C++ code generation, to select a planning method for FFT library calls, implement a getPlanMethod method in an FFT library callback class. For more information about an FFT library callback class, see coder.