- fftw - fast fourier transform that use fftw library
- fftw_flags - set computation method of fast fourier transform of the fftw function
- fftw_inplace - set if transform is realized in place
- fftw_norm - set if inverse transform of the fftw function is normalized
- freefftw_plan - free all the planners stored in memory
- pushfftw_plan - push the last used fftw planner in memory