Full description
D.J. Bernstein Fast Fourier Transform (djbfft) is an extremely
fast library for floating-point convolution. The current version
holds most of the speed records for double-precision FFTs on
general-purpose computers.
djbfft provides power-of-2 complex FFTs, real FFTs at twice the speed,
and fast multiplication of complex arrays. Single precision and double
precision are equally supported.