Almost orthogonal functions

Almost-orthogonal functions, which are obtained by perturbing orthogonal functions, do not exactly satisfy the orthogonality conditions. The notion of almost-orthogonal functions is explained with examples. An error analysis of expansion coefficients based on almost-orthogonal functions is given. Using examples derived from sinusoids, it is shown how computational advantage can be obtained by using almost-orthogonal functions in signal processing.<
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