 That is, it takes a function from the time domain into the frequency domain; it is a decomposition of a function into sinusoids of different frequencies; in the case of a Fourier series or discrete Fourier transform, the sinusoids are harmonics of the fundamental frequency of the function being analyzed.When the function is a function of time and represents a physical signal, the transform has a standard interpretation as the frequency spectrum of the signal.The magnitude of the resulting complex-valued function at frequency represents the amplitude of a frequency component whose initial phase is given by the phase of .