fft - Compute the fast Fourier transform of input buffer.
Inputs:
in [BUFFER] [REQUIRED]: input buffer in temporal domain.
Outputs:
real [BUFFER]: real part of FFT coefficients. imaginary [BUFFER]: imaginary part of FFT coefficients. module [BUFFER]: modules of FFT coefficients. phase [BUFFER]: phases of FFT coefficients.
Computes the fast Fourier transform of the (real) input signal, using FFTW3. The output buffers will be of size (n / 2) + 1 if n is the size of the input buffer, as the input signal is taken to be real.
It outputs the complex coefficients in two forms: the cartesian and polar forms, which are stored respectively in real and imaginary for the cartesian, and module and phase for the polar form.
Both are always computed simultaneously.
FFTW3 does not always give the same output across different platforms. Attention has been paid so that it normally always select the same algorithm on the same platform, so on the same computer results are expected to always be reproducible bit for bit, however across systems they may differ marginally.