Hi all, I am solving a six field battery problem (concentration and potential for each of the two solid and one electrolyte domains) and I want to experiment with nested/recursice fieldsplitting. I have the IS's and am able to use these to define my PCFieldSplitsSetIS(). However, I can imagine this getting really messy from a programming standpoint, especially once I need to add temperature into the mix, so it is my hope that I can translate these index sets and fields into a DM (maybe DMShell?) so that I can just rely on command line options to play around with various combinations of field assignments and splits (e.g. -pc_fieldsplit_X_fields)
However, it doesn't seem clear to me how I would create a DM when you already know the IS's for each fields. If I understand functions like DMCreateFieldDecomposition() correctly, it seems that it returns to you the IS's and sub DM's associated with the original DM, whereas I want to do it the other way around. Perhaps the "reversal" of something like DMCreateFieldIS() <https://www.mcs.anl.gov/petsc/petsc-dev/src/dm/interface/dm.c.html#DMCreateFieldIS>, where you convert the IS into a PetscSection or is there an easier/better way? Any thoughts/help appreciated! Justin