[petsc-users] Generally constrained solvers with FenicsX

[Biro Clouds]

Hi all,

I've been struggling for some time now trying to get a generally
constrained solver (ideally ALMM, but PDIPM might work too) to work in
python, specifically with FEniCS X. My model is an incremental variational
approach to plasticity and normally requires two lagrange multipliers
alongside the energy functional terms. However, through experimentation
outside of this environment, I found that dealing with these lagrange
multipliers as non linear constraints in the SciPy optimise function worked
very well and has allowed me to achieve some good results. I'd like to
implement an approach as similar as possible to this with a TAO solver, and
ALMM method looks the most similar to me. I have looked in the Fenics
discourse forum and there is vanishingly small amounts of PETSc TAO content
there, and I've found no good example of ALMM solvers in python, or even
the  setEqualityConstraint() function anywhere. I'm relatively new to all
this and cannot read C code unfortunately, so the constrained example in C
is not much help to me, especially as the implementation seems completely
different to python.

Kind regards,

Magnus
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