Subspace projection extrapolation scheme for transient field simulations

A subspace projection extrapolation (SPE) scheme is introduced for the start vector generation for the iterative solution of the algebraic systems of equations resulting from implicit time integration schemes for electromagnetic discrete field formulations. The SPE scheme yields optimal linear combinations from multiple available start vectors. Spectral components of the exact solution contained therein are optimally resolved which causes subsequently started conjugate gradient (CG) methods to converge according to a reduced effective condition number similar to deflated CG methods. Numerical tests show a significant improvement in numerical efficiency with the SPE scheme in comparison to established extrapolation methods.