Cholesky decomposition
1 Cholesky Decomposition
A symmetric and positive definite matrix can be efficiently decomposed into a lower and upper triangular matrix. For a matrix of any type, this is achieved by the LU decomposition which factorizes . If satisfies the above criteria, one can decompose more efficiently into where is a lower triangular matrix with positive diagonal elements. is called the Cholesky triangle.
To solve , one solves first for , and then for .
A variant of the Cholesky decomposition is the form , where is upper triangular.
Cholesky decomposition is often used to solve the normal equations in linear least squares problems; they give , in which is symmetric and positive definite.
To derive , we simply equate coefficients on both sides of the equation:
Solving for the unknowns (the nonzero s), for and , we get:
Because is symmetric and positive definite, the expression under the square root is always positive, and all are real.
References
- 1 Originally from The Data Analysis Briefbook (http://rkb.home.cern.ch/rkb/titleA.htmlhttp://rkb.home.cern.ch/rkb/titleA.html)
Title | Cholesky decomposition |
Canonical name | CholeskyDecomposition |
Date of creation | 2013-03-22 12:07:38 |
Last modified on | 2013-03-22 12:07:38 |
Owner | gufotta (12050) |
Last modified by | gufotta (12050) |
Numerical id | 16 |
Author | gufotta (12050) |
Entry type | Definition |
Classification | msc 62J05 |
Classification | msc 65-00 |
Classification | msc 15-00 |
Synonym | Cholesky factorization |
Synonym | matrix square root |
Related topic | SquareRootOfPositiveDefiniteMatrix |
Defines | Cholesky triangle |