Python PETSc Example BP1 #1806
Python PETSc Example BP1 #1806
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examples/python/bpsraw.py
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| matrix = PETSc.Mat().createAIJ([num_dofs, num_dofs], comm=PETSc.COMM_WORLD) | ||
| matrix.setFromOptions() | ||
| matrix.setUp() | ||
| for i in range(num_dofs): | ||
| e_vec = ceed.Vector(num_dofs) | ||
| r_vec = ceed.Vector(num_dofs) | ||
| e_vec.set_value(0.0) | ||
| r_vec.set_value(0.0) | ||
| with e_vec.array_write() as arr: | ||
| arr[i] = 1.0 | ||
| op.apply(e_vec, r_vec) | ||
| with r_vec.array_read() as r_arr: | ||
| matrix.setValues(range(num_dofs), [i], r_arr) | ||
| matrix.assemble() |
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You'll want a MatShell, not a MatAIJ
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Apologies for leaving this a bit stale. Addressing this led to a lot of other changes. I had trouble setting the matrix type to "shell" and applying context, kept getting segmentation faults. So, instead of using the "shell" type, I used the "python" type and set the context through a python class. Pulled that implementation from the petsc4py 2DPoisson example (about half way down) --> link. I'll tidy up what I have a submit an update soon.
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Overall this is looking like the right approach. The big thing is to try to avoid copying around data during frequent operations, like the matrix application
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Thank you for all the suggestions! Definitely, keeping the data in place would mean less overhead and better efficiency
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@tylercollins5737 , thank you for your work. Are you able to address the reviewer's comments? |
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@valeriabarra I was able to get it working using the "python" matrix type, MatAIJ was not the best. I believe the "python" type and MatCreateShell can achieve the same thing. |
| with self.v.array_read() as va: | ||
| y.setValues(range(lo, hi), va[lo:hi]) | ||
| y.assemble() |
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Ideally, you'd set v to use y's array before you apply the libCEED operator
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That makes more sense, thank you!
| def CreateRestriction(ceed, mesh_elem, P, num_comp, ndofs, offsets): | ||
| return ceed.ElemRestriction(mesh_elem, P, num_comp, 1, ndofs, offsets, cmode=libceed.USE_POINTER) |
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If this just wraps another function call, I think its clearer to use the function call itself
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Totally agree, I have another CreateRestriction function that reflects C but its a WIP
Co-authored-by: Jeremy L Thompson <[email protected]>
Hello!
This is a Python implementation of bpsraw.c for BP1 and was initially discussed in #1774 . I'm aiming to recreate the benchmark behavior using libceed and petsc4py. I appreciate any feedback or indications I'm headed in the right direction!
It does run, but this is a work in progress. Remaining tasks: