Application of the Implicitly Updated Arnoldi Method with a Complex Shift-and-Invert Strategy in MHD

The implicitly updated Arnoldi method introduced by Sorensen with an internal QR-iteration is a very useful eigenvalue solver for nonsymmetric eigenvalue problems. To make this method rigorous in finding internal eigenvalues, a complex shift-and-invert strategy is used. Therefore a complex variant of the method has been constructed and the method has been compared with a Lanczos method, as implemented by Cullum et al., for a practical problem in magnetohydrodynamics.