[BUG] uw.function.evaluate not working in parallel

[bknight1]

I'm getting the following error when the code is doing an uw.function.evaluate:

(uw) benknight@MacBook-Pro UW3_timing % mpiexec -np 4 python3 eval_error_test.py


[2]PETSC ERROR: --------------------- Error Message --------------------------------------------------------------
[2]PETSC ERROR: Invalid argument
[2]PETSC ERROR: Global dof 2 for point 66 is not the unconstrained 1
[2]PETSC ERROR: WARNING! There are unused option(s) set! Could be the program crashed before usage or a spelling mistake, etc!
[2]PETSC ERROR:   Option left: name:-dm_plex_gmsh_mark_vertices value: true source: code
[2]PETSC ERROR:   Option left: name:-dm_plex_gmsh_multiple_tags value: true source: code
[2]PETSC ERROR:   Option left: name:-dm_plex_gmsh_use_regions (no value) source: code
[2]PETSC ERROR:   Option left: name:-dm_plex_hash_location (no value) source: code
[2]PETSC ERROR: See https://petsc.org/release/faq/ for trouble shooting.
[2]PETSC ERROR: Petsc Release Version 3.21.5, unknown 
[2]PETSC ERROR: eval_error_test.py on a arch-darwin-c-debug named MacBook-Pro.lan by benknight Wed Oct  8 17:44:02 2025
[2]PETSC ERROR: Configure options --COPTFLAGS="-g -O3" --CXXOPTFLAGS="-g -O3" --FOPTFLAGS="-g -O3" --with-petsc4py=1 --with-shared-libraries=1 --with-cxx-dialect=C++11 --with-make-np=4 --download-zlib=1 --download-cmake=1 --download-hdf5=1 --download-mumps=1 --download-parmetis=1 --download-metis=1 --download-superlu=1 --download-hypre=1 --download-scalapack=1 --download-superlu_dist=1 --download-pragmatic=1 --download-ctetgen --download-eigen --download-superlu=1 --download-triangle --useThreads=1
[2]PETSC ERROR: #1 PetscSectionCreateGlobalSection() at /Users/benknight/software/petsc-3.21.5/src/vec/is/section/interface/section.c:1517
[2]PETSC ERROR: #2 DMGetGlobalSection() at /Users/benknight/software/petsc-3.21.5/src/dm/interface/dm.c:4635
[2]PETSC ERROR: #3 DMGetSectionSF() at /Users/benknight/software/petsc-3.21.5/src/dm/interface/dm.c:4708
[2]PETSC ERROR: #4 DMLocalToGlobalBegin() at /Users/benknight/software/petsc-3.21.5/src/dm/interface/dm.c:3065
Traceback (most recent call last):
  File "/Users/benknight/Documents/Research/Modelling/UW-models/Setonix_stuff/UW3_timing/eval_error_test.py", line 10, in <module>
Traceback (most recent call last):
  File "/Users/benknight/Documents/Research/Modelling/UW-models/Setonix_stuff/UW3_timing/eval_error_test.py", line 10, in <module>
    data = uw.function.evaluate(v.sym, mesh.data, evalf=True)

Not sure when it was introduced as I haven't run any models in parallel for a while.

I'm on the current dev branch with petsc v3.21.5

To recreate:

import underworld3 as uw

mesh = uw.meshing.UnstructuredSimplexBox()


v = uw.discretisation.MeshVariable('u',    mesh,  mesh.dim, degree=2 )
p = uw.discretisation.MeshVariable('p',    mesh,  1, degree=1 )


data = uw.function.evaluate(v.sym, mesh.data, evalf=True)

print(data)

To add, the evaluate will work if the p mesh variable is not defined.