A class which encapsulates the functionality of an LU factorization.
For a matrix A, the LU factorization is a pair of lower triangular matrix L and upper triangular matrix U so that A = L*U.
In the Math.NET implementation we also store a set of pivot elements for increased numerical stability. The pivot elements encode a permutation matrix P such that P*A = L*U.
The computation of the LU factorization is done at construction time.