Wiktionary
matrix decomposition
n. (context mathematics English) A process by which a rectangular table of numbers or abstract quantities that can be added and multiplied is broken down into simpler numerical building blocks.
Wikipedia
Matrix decomposition
In the mathematical discipline of linear algebra, a matrix decomposition or matrix factorization is a factorization of a matrix into a product of matrices. There are many different matrix decompositions; each finds use among a particular class of problems.