The document discusses Fourier series and their application in power electronics. Fourier series can be used to represent nearly any periodic function as a sum of sinusoids. Any periodic waveform produced by a real circuit meets the conditions for a Fourier series representation. In power electronics, Fourier series are used to analyze waveforms where jumps occur as switches select circuit connections. The integrals for coefficients in piecewise sinusoidal waveforms can be computed numerically using programming languages. Only the desired, or "wanted", Fourier component is of interest for most applications in power electronics.