If we have a function $f(t)$ for $ t = a, a + \triangle t, ..., b=a+n \triangle t$. And then I use the discrete Fourier transform on $f(t)$. Then what is the frequency domain of the result?
For example in Python module Numpy, the DFT only gives you the amplitude of the frequencies (list of amplitudes). But it does not say which amplitude is for which frequency.