Apologies. If it helps, there is one cell of overlap in this small test case for a 2D mesh that is 1 cell in height and a number of cells in length. .
process 0 Petsc VecGetLocalSize 2750 size(stateVecV) 2750 process 1 Petsc VecGetLocalSize 2640 size(stateVecV) 2640 On Fri, Jan 6, 2023 at 9:51 AM Matthew Knepley <[email protected]> wrote: > On Fri, Jan 6, 2023 at 9:37 AM Nicholas Arnold-Medabalimi < > [email protected]> wrote: > >> Hi Matt >> >> I made a typo on the line statVecV(offset) = <set to something> in my >> example, I agree. (I wrote that offhand since the actual assignment is much >> larger) I should be statVecV(offset+1) = <assignment> so I'm confident it's >> not a 1 0 indexing thing. >> >> My question is more related to what is happening in the offsets. c0 and >> c1 are pulled using DMplexgetheight stratum, so they are zero-indexed >> (which is why I loop from c0 to (c1-1)). >> >> For the size inquiries. on processor 0 >> Petsc VecGetSize(stateVec) 5390 >> > > I need to see VecGetLocalSize() > > Matt > > >> size(stateVecV) 2640 >> >> on processor 1 >> Petsc VecGetSize 5390 >> size(stateVecV) 2750 >> >> It's quite weird to me that processor one can have a positive offset that >> is less than its starting ownership index (in the initial email output). >> >> Thanks for the assistance >> Nicholas >> >> >> On Fri, Jan 6, 2023 at 9:20 AM Matthew Knepley <[email protected]> wrote: >> >>> On Fri, Jan 6, 2023 at 2:28 AM Nicholas Arnold-Medabalimi < >>> [email protected]> wrote: >>> >>>> Hi Petsc Users, >>>> >>>> I'm working with a dmplex system with a subsampled mesh distributed >>>> with an overlap of 1. >>>> >>>> I'm encountering unusual situations when using VecGetOwnershipRange to >>>> adjust the offset received from a global section. The logic of the >>>> following code is first to get the offset needed to index a global vector >>>> while still being able to check if it is an overlapped cell and skip if >>>> needed while counting the owned cells. >>>> >>> >>> >>>> >>>> call DMGetGlobalSection(dmplex,section,ierr) >>>> call VecGetArrayF90(stateVec,stateVecV,ierr) >>>> call VecGetOwnershipRange(stateVec,oStart,oEnd,ierr) >>>> do i = c0, (c1-1) >>>> >>>> call PetscSectionGetOffset(section,i,offset,ierr) >>>> write(*,*) "cell",i,"offset",offset,'oStart',oStart, offset-oStart >>>> >>>> if(offset<0) then >>>> cycle >>>> endif >>>> offset=offset-oStart >>>> plexcells=plexcells+1 >>>> stateVecV(offset)= <set to something> enddo >>>> >>>> I'm noticing some very weird results that I've appended below. The >>>> GetOffset documentation notes that a negative offset indicates an unowned >>>> point (which I use to cycle). However, the offset subtraction with oStart >>>> will yield an illegal index for the Vector access. I see that on the >>>> documentation for GetOwnershipRange, it notes that this may be >>>> "ill-defined" but I wanted to see if this is type of ill-defined I can >>>> expect or there is just something terribly wrong with my PetscSection.(both >>>> the Vec and Section were produced from DMPlexDistributeField so should by >>>> definition have synchronized section information) I was wondering if there >>>> is a possible output and/or the best way to index the vector. I'm thinking >>>> of subtracting the offset of cell 0 perhaps? >>>> >>> >>> Can you show your vector sizes? Are you sure it is not the fact that F90 >>> arrays use 1-based indices, but these are 0-based offsets? >>> >>> Thanks, >>> >>> Matt >>> >>> >>>> on rank 0 >>>> >>>> cell 0 offset 0 oStart 0 0 >>>> cell 1 offset 55 oStart 0 55 >>>> cell 2 offset 110 oStart 0 110 >>>> cell 3 offset 165 oStart 0 165 >>>> cell 4 offset 220 oStart 0 220 >>>> cell 5 offset 275 oStart 0 275 >>>> cell 6 offset 330 oStart 0 330 >>>> cell 7 offset 385 oStart 0 385 >>>> cell 8 offset 440 oStart 0 440 >>>> cell 9 offset 495 oStart 0 495 >>>> cell 10 offset 550 oStart 0 550 >>>> cell 11 offset 605 oStart 0 605 >>>> cell 12 offset 660 oStart 0 660 >>>> cell 13 offset 715 oStart 0 715 >>>> >>>> and on rank one >>>> cell 0 offset 2475 oStart 2640 -165 >>>> cell 1 offset 2530 oStart 2640 -110 >>>> cell 2 offset 2585 oStart 2640 -55 >>>> cell 3 offset 2640 oStart 2640 0 >>>> cell 4 offset 2695 oStart 2640 55 >>>> cell 5 offset 2750 oStart 2640 110 >>>> cell 6 offset 2805 oStart 2640 165 >>>> cell 7 offset 2860 oStart 2640 220 >>>> cell 8 offset 2915 oStart 2640 275 >>>> cell 9 offset 2970 oStart 2640 330 >>>> cell 10 offset 3025 oStart 2640 385 >>>> cell 11 offset 3080 oStart 2640 440 >>>> cell 12 offset 3135 oStart 2640 495 >>>> cell 13 offset 3190 oStart 2640 550 >>>> cell 14 offset 3245 oStart 2640 605 >>>> cell 15 offset -771 oStart 2640 -3411 >>>> >>>> >>>> Sincerely >>>> Nicholas >>>> >>>> -- >>>> Nicholas Arnold-Medabalimi >>>> >>>> Ph.D. Candidate >>>> Computational Aeroscience Lab >>>> University of Michigan >>>> >>> >>> >>> -- >>> What most experimenters take for granted before they begin their >>> experiments is infinitely more interesting than any results to which their >>> experiments lead. >>> -- Norbert Wiener >>> >>> https://www.cse.buffalo.edu/~knepley/ >>> <http://www.cse.buffalo.edu/~knepley/> >>> >> >> >> -- >> Nicholas Arnold-Medabalimi >> >> Ph.D. Candidate >> Computational Aeroscience Lab >> University of Michigan >> > > > -- > What most experimenters take for granted before they begin their > experiments is infinitely more interesting than any results to which their > experiments lead. > -- Norbert Wiener > > https://www.cse.buffalo.edu/~knepley/ > <http://www.cse.buffalo.edu/~knepley/> > -- Nicholas Arnold-Medabalimi Ph.D. Candidate Computational Aeroscience Lab University of Michigan
