## Version 3.3.1

18th June 2013

Recent Changes

• Integer

### HSL_MC68 Symmetric sparse matrix: compute elimination orderings

Given a symmetric sparse matrix $A={\left\{{a}_{ij}\right\}}_{n×n}$, HSL_MC68 computes elimination orderings that are suitable for use with a sparse direct solver. Currently the following choices are available

• Approximate minimum degree ordering (with provision for some dense, rows and columns) using MC47,
• Minimum degree ordering using the methodology of MA27,
• Nested bisection ordering using MeTiS,
• MA47 ordering for indeﬁnite matrices which may generate a combination of both $1×1$ and $2×2$ pivots.