In this paper, we equip Cn with an indefinite scalar product with a specific Hermitian matrix, and our aim is to develop some block Krylov methods to indefinite mode. In fact, by considering the block Arnoldi, block FOM, and block Lanczos methods, we design the indefinite structures of these block Krylov methods; along with some obtained results, we offer the application of this methods in solving linear systems, and as the testifiers, we design numerical examples.

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We describe an indefinite state of Arnoldi's method for solving the eigenvalues problems. In the following, we scrutinize the indefinite state of Lanczos' method for solving the eigenvalue problems and we show that this method for the -Hermitian matrices works much better than Arnoldi's method.

In this paper, we firstly derive a general expression for the entries of the m th ( m ∈ ℕ ) power for two certain types of tridiagonal matrices of arbitrary order. Secondly, we present a method for computing the positive integer powers of the anti-tridiagonal matrix corresponding to these matrices. Also, we give Maple 18 procedures in order to verify our calculations.