This equation can be discretized. For simplicity, assume that samples of the input and output are taken at evenly spaced points in time separated by time. Let the samples of be represented by the sequence , and let be represented by the sequence , which correspond to the same points in time. Making these substitutions,
This equation can be discretized For simplicity assume that samples of the input and output are taken at evenly spaced points in time separated by time Let the samples of be represented by the sequence  and let be represented by the sequence  which correspond to the same points in time Making these substitutions