A parameterized block-splitting preconditioner for indefinite least squares problem

We present a stationary iteration based upon a block splitting for a class of indefinite least squares problem. Convergence of the proposed method is investigated and optimal value of the involving parameter is used. The induced preconditioner is applied to accelerate the convergence of the GMRES method for solving the problem. We also analysed the eigenpair distribution of the preconditioned matrix. {We assess the efficiency of the proposed preconditioner by presenting results from a numerical comparison with several existing preconditioners.