Iterative Methods by Spd and Small Subspace Solvers for Nonsymmetric or Indefinite Problems
نویسنده
چکیده
This paper is devoted to a class of iterative methods for solving nonsymmetric or indeenite problems that are dominated by some SPD (symmetric positive deenite) problems. The algorithm is based on a direct solver for the original equation restricted on a small subspace and a given iterative method for the SPD equation. It is shown that any convergent iterative method for the SPD problem will give rise to an algorithm that converges with a comparable rate if the small subspace is properly chosen. Furthermore a number of preconditioners that can be used with GMRES type methods are also obtained.
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