CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Wiki > LU decomposition

LU decomposition

From CFD-Wiki

Revision as of 20:42, 15 December 2005 by Tsaad (Talk | contribs)
Jump to: navigation, search

LU Solvers

For the system of equations A\cdot\phi=B.
The solvers based on factorization are widely popular. The factorization of a non singular matrix A in two matrices L and U, called lower and upper matrices, leads to a direct procedure for the evaluation of the inverse of the matrix. Thus making it possible to calculate the solution vector with given source vector. It now remains a two step process: a forward substitution followed by a backward substitution.

Algorithm

Calculate LU factors of A
 A\cdot \phi = (LU)\cdot \phi = L(U\cdot\phi)=LY=B
Solve LY=B by forward substitution
 Y = L^{-1} B
Solve U\phi =Y by backward substitution
 \phi = U^{-1}Y





Return to Numerical Methods

My wiki