Mutual coherence (linear algebra)

In linear algebra, mutual coherence (or simply coherence) measures the maximum similarity between any two columns of a matrix, defined as the largest absolute value of their cross-correlations. First explored by David Donoho and Xiaoming Huo in the late 1990s for pairs of orthogonal bases, it was later expanded by Donoho and Michael Elad in the early 2000s to study sparse representations—where signals are built from a few key components in a larger set.

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