Frequency spectrum
In mathematics, the frequency spectrum can be found from the result of a Fourier-related transform of a function. It shows the decomposition of a function into frequency components (sinusoidal basis functions). As opposed to the power spectrum, the frequency spectrum should not only include the energy distribution among the frequency domain but also spatial or phase angle information.Ideally, one would use the full Fourier transform to compute the frequency spectrum, but often only a finite set of discrete samples is available, in which case one generally applies spectral estimation techniques to some form of discrete Fourier transform.