In this paper we empirically evaluate a recently proposed Fast Approximate Discrete
Fourier Transform (FADFT) algorithm, FADFT-2, for the first time. FADFT-2 returns approximate
Fourier representations for frequency-sparse signals and works by random sampling. Its implemen-
tation is benchmarked against two competing methods. The first is the popular exact FFT imple-
mentation FFTW Version 3.1. The second is an implementation of FADFT-2’s ancestor, FADFT-1.
Experiments verify the theoretical runtimes of both FADFT-1 and FADFT-2. In doing so it is shown
that FADFT-2 not only generally outperforms FADFT-1 on all but the sparsest signals, but is also
significantly faster than FFTW 3.1 on large sparse signals. Furthermore, it is demonstrated that
FADFT-2 is indistinguishable from FADFT-1 in terms of noise tolerance despite FADFT-2’s better
execution time.