Build libmesh (without --enable-complex) with PETSc (with complex scalars)

[rainiscold]

Hello all,

Can I compile libmesh without enabling complex but with a PETSc that has enabled complex scalars? I ran into an error in this case, it complains that I have to configure libmesh with complex numbers.

I built PETSc with scalar complex, I have no problem building libmesh with "--enable-complex".

The origin of the problem is: I want to solve complex eigenvalue problem in MOOSE. MOOSE can only compile with libmesh (real numbers only). So I want to go around libmesh and manipulate complex numbers in PETSc. See idaholab/moose#29886

Does anyone know any solution to this? Thank you!

[rainiscold]

I don't know if I can go around PETSc because SLEPc heavily relies on PETSc. I'd appreciate it if you @roystgnr can offer some insights.

[jwpeterson]

I would not expect this to be easily possible, unfortunately. All of our LinearSolver and related classes are templated on (and only instantiated for) the Number type, and there is a deeply ingrained assumption that libMesh Number and PetscScalar are consistent with one another. We run into a similar issue when trying to build libmesh+PETSc with (one of the various possible) higher-precision real-valued types as well.