LDL is a set of concise routines for factorizing symmetric
positive-definite sparse matrices, with some applicability to symmetric
indefinite matrices. Its primary purpose is to illustrate much of the
basic theory of sparse matrix algorithms in as concise a code as possible,
including an elegant new method of sparse symmetric factorization that
computes the factorization row-by-row but stores it column-by-column.
This package is part of SuiteSparse.