[Dune] Read in matrix and rhs, solve linear system

[Buesing, Henrik]

> If it is not about speed, then you might be able to solve such a system
> on process. Compared to other AMG's we do not need that much memory.

[Buesing, Henrik] Ok. I will try to benchmark in serial or come up with a smaller system.
I converted my matrix to matrixmarket and ran matrixmarket-amg

Below is the output. Is there a way to find out why he aborted? 

Henrik


%%MatrixMarket
%%MatrixMarket
Level 0 has 6.3058e+06 unknowns, 6.3058e+06 unknowns per proc (procs=1)
aggregating finished.
Level 1 has 2.45706e+06 unknowns, 2.45706e+06 unknowns per proc (procs=1)
aggregating finished.
Level 2 has 904947 unknowns, 904947 unknowns per proc (procs=1)
aggregating finished.
Level 3 has 500740 unknowns, 500740 unknowns per proc (procs=1)
aggregating finished.
Level 4 has 179584 unknowns, 179584 unknowns per proc (procs=1)
aggregating finished.
Level 5 has 85507 unknowns, 85507 unknowns per proc (procs=1)
aggregating finished.
Level 6 has 39132 unknowns, 39132 unknowns per proc (procs=1)
aggregating finished.
Level 7 has 21563 unknowns, 21563 unknowns per proc (procs=1)
aggregating finished.
Level 8 has 13195 unknowns, 13195 unknowns per proc (procs=1)
aggregating finished.
Level 9 has 10225 unknowns, 10225 unknowns per proc (procs=1)
aggregating finished.
Stopped coarsening because of rate breakdown 10225/9256=1.10469<1.2
operator complexity: 1.62054
Building hierarchy of 10 levels (inclusive coarse solver) took 223.879 seconds.
Building hierarchy took 223.88 seconds
=== GeneralizedPCGSolver
 Iter          Defect            Rate
    0        0.0181497
terminate called after throwing an instance of 'Dune::MathError'