Abstract: In this paper we investigate structured backward errors for three kinds of generalized saddle point systems where the matrix is not symmetric and its block is not zero and has perturbations. Computable formula of backward errors are derived. The expressions are useful for testing the stability of practical algorithms. [Copyright &y& Elsevier]
Abstract: In this paper, we construct two classes of -disjunct matrix with subspaces in a symplectic space and prove that the ratio efficiency of two constructions are smaller than that of D’yachkov et al. (2005) . [Copyright &y& Elsevier]