Fourier Theorem: In the early 19th century, the French mathematician Jean-Baptiste Fourier states that: Any periodic waveform can be expressed as the sum of sine waves with frequencies at integer or harmonic multiples of the fundamental frequency of the waveform and with appropriate maximum amplitudes and phases. A square wave of 1 kHz is composed of a 1 kHz sine wave and its odd multiples (Harmonics) with diminishing amplitudes: A Sin(2p(f[SUB]1[/SUB])t) + A/3 sin(2p(3f[SUB]1[/SUB])t) + A/5 sin(2p(5f[SUB]1[/SUB])t) + A/7 sin(2p(7f[SUB]1[/SUB])t)