Parameters in FEniCS 2018/2019 equivalent to LUSolver('mumps') from 2017

[plugged]

If you want to have more specific control over petsc, take a look at my answer here:

Preconditioner not working or bug?

The results are “correct” since fenics / petsc uses the preconditioned residual in order to check the convergence criterion. Also, the petsc faq says that this discrepancy can happen, e.g., for saddle point problems: https://www.mcs.anl.gov/petsc/documentation/faq.html#kspdiverged You could circumvent this by applying the preconditioner from the right hand side, since you will then always have an unpreconditioned norm in your convergence check. A MWE could look like this: from fenics import * …

There it is shown how you can use petsc directly, and how you can define which solver is chosen using “command line options” for petsc.