Translations:Wavelets - book/9/en

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This filter is called a causal finite-impulse-response filter or simply a causal FIR filter. The set of coefficients makes up the impulse-response function, which we recognize as a causal wavelet with a finite number of coefficients. In other words, the impulse-response function of a causal FIR filter is a causal wavelet with a finite number of coefficients. In general, a digital filter is causal if and only if its impulse-response function is a causal wavelet. A digital filter is noncausal if and only if its impulse-response function is a noncausal wavelet. A digital filter is purely noncausal if and only if its impulse-response function is a purely noncausal wavelet.