**Definition:** The L1 norm is the p=1 norm case of Lebesgue’s Lp spaces. Norms are positive mappings from a vector space X over the field of real or complex numbers into the real numbers that abides by the principle of superposition. Norms are often a measure of an object size and hence they are distance functions (from the origin) e.g. metrics. There exist a myriad of norms with Lebesgue’s Lp norms being perhaps the most familiar.

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