TY - JOUR T1 - Preconditioning by Fast Direct Methods for Nonself-Adjoint Nonseparable Elliptic Equations JF - SIAM Journal on Numerical Analysis Y1 - 1986 A1 - Elman, Howard A1 - Schultz, Martin H. AB - We consider the use of fast direct methods as preconditioners for iterative methods for computing the numerical solution of nonself-adjoint elliptic boundary value problems. We derive bounds on convergence rates that are independent of discretization mesh size. For two-dimensional problems on rectangular domains, discretized on an n × n grid, these bounds lead to asymptotic operation counts of O(n2 log n log ε-1) to achieve relative error ε and O(n2(log n)2) to reach truncation error. VL - 23 SN - 0036-1429 UR - http://www.jstor.org/stable/2157450 CP - 1 ER -