What is the "default" linear solver/preconditioner?

1

I am wondering what the default solvers are. When I check the default options I get:

info(LinearVariationalSolver.default_parameters(), True)

linear_variational_solver  |    type    value  
---------------------------------------------
linear_solver              |  string  default  
preconditioner             |  string  default

I had the impression that it was PetSc, but I can’t find what the default means (some built-in solver)?

2

With the standard build with a PETSc backend: UMFPACK in serial and MUMPS in parallel.