[Nek5000-users] How to use AMG instead of XXT with Nek5000 v17.0

[nek5000-users at lists.mcs.anl.gov]

This has changed, see Release Notes. 

Workflow:

1) set p40=1 in your .rea or preconditioner=semg_amg in .par
2) run Nek5000 (this will create the amgdump files in case they don't exist)
3) run the amg_hypre tool (this will create the input files required for AMG)
4) run Nek5000

Note: Step (2) and (3) are only needed once.