Iterative two-level algorithm for nonsymmetric or indefinite elliptic problems

In this paper, a new iterative two-level algorithm is presented for solving the finite element discretization nonsymmetric or indefinite elliptic problems. The uses same coarse space as traditional two-grid algorithm, but its “fine space” higher order under grid. Therefore, only needs one grid, and computational cost much lower than algorithm. Finally, compared with numerical experiments show that to achieve convergence order.