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Book Review: Electrical Power Systems: Design and Analysis

sequently defines the power spectrum as the Fourier transform of this function, despite the fact that such transforms do not exist (in a mathematical sense) for stationary stochastic processes which possess either 'line' spectra or 'mixed' spectra. This feature is particularly surprising since in the earlier chapters the author goes into considerable detail in explaining the difference between discrete, continuous, and 'mixed' probability distributions, and could have used this as a very convenient starting point for a corresponding discussion of power spectra, and at the same time drawn the reader's attention to the isomorphism between probability distribution and power spectra. The treatment of spectral estimation via spectral windows is again rather poor, and conveys very little of the flavour of this topic. The crucial statistical parameters which underlie the whole subject of spectral windows (namely, variance and bias), are relegated to a small sub-section later in the chapter, and the vast statistical literature on this topic seems to have been largely ignored. In summary, this is a book which is written in a style aimed primarily at engineers, contains a large number of interesting examples, but is not without its faults. M. B. PRIESTLEY, Professor ofMathematics, UMIST