The smoothed aggregation solver supports nonsymmetric (i.e., non-Hermitian) and indefinite matrices, through recent advances in multigrid research. The demo highlighted here constructs a solver for a small nonsymmetric recirculating flow problem. The out-of-the-box example diverges, while more advanced options yield a convergent solver.

Using

python demo.py --solver 1

we observe the following convergence history.