...-type preconditioning. And because of concerns about memory usage, GMRES(m) is a good choice if necessary. Originality/value – In this paper, for overcoming difficulties of bad numerical stability resulting from Lagrange multiplier method, together with increasing scale of problems in engineering...

... method for solving equations using Lagrange multiplier method, and facilitates the choice of the reordering for the iterative method. Design/methodology/approach – To reordering the coefficient matrix before a preconditioned iterative method will greatly impact its convergence behavior...