Complex sentence: For many functions of practical interest one can define an operation that reverses this: the "inverse Fourier transformation", also called "Fourier synthesis", of a frequency domain representation combines the contributions of all the different frequencies to recover the original function of time.
Split into simpler sentences: For many functions of practical interest one can define an operation which reverses this. The "inverse Fourier transformation", also called "Fourier synthesis", of a frequency domain representation combines the contributions of all the different frequencies to recover the original function of time.