Incomplete block factorization preconditiong for indefinite elliptic problems (Q1964050)

Using the finite difference method to solve an indefinite elliptic problem results in a linear system whose coefficient matrix is block tridiaginal and symmetric indefinite. The author shows that specific incomplete block factorization exists for this indefinite matrix if the mesh size is reasonably small, and this factorization can be used as an efficient preconditioner. The eigenvalues of the preconditioned matrix are estimated. Numerical results are also presented.