EXPLOITING ZEROS ON THE DIAGONAL IN THE DIRECT SOLUTION OF INDEFINITESPARSE SYMMETRICAL LINEAR-SYSTEMS

We describe the design of a new code for the solution of sparse indefi nite symmetric linear systems of equations. The principal difference b etween this new code and earlier work lies in the exploitation of the additional sparsity available when the matrix has a significant number of zero diagonal entries. Other new features have been included to en hance the execution speed, particularly on vector and parallel machine s.