Parameterized rotated block preconditioning techniques for block two-by-two systems with application to complex linear systems

In this paper, based on the rotated block triangular preconditioning technique, we present a class of parameterized rotated block preconditioners to accelerate Krylov subspace iterative methods with coefficient matrices of nonsymmetric sub‐blocks. The parameterized rotated block preconditioners can be seen as a generalization of the rotated block triangular preconditioners. The eigen‐properties of the corresponding preconditioned matrices are analyzed. Numerical experiments are used to demonstrate the feasibility and effectiveness of the parameterized rotated block preconditioners.