Understanding the FFT (Fast Fourier Transform). A tutorial on the algorithm, and software for laymen, students, technicians and working engineers / Понимание быстрого преобразования Фурье. Учебное пособие по алгоритму и программному обеспечению

It has been said that a good definition first throws the thing to be defined into a very large pool (i.e. a very broad category) and then pulls it out again (i.e. describes the unique characteristics that differentiate it from the other members of that category). That is the approach we will use in tackling the question; "What, exactly, is the Fourier series?" <...>