[petsc-users] PetscViewer with 64bit

[Mike Michell]

Thanks for the comments.
To be precise on the question, the entire part of the header of the .vtu
file is attached:

<?xml version="1.0"?>
<VTKFile type="UnstructuredGrid" version="0.1" byte_order="LittleEndian">
  <UnstructuredGrid>
    <Piece NumberOfPoints="4872" NumberOfCells="4000">
      <Points>
        <DataArray type="Float64" Name="Position" NumberOfComponents="3"
format="appended" offset="0" />
      </Points>
      <Cells>
        <DataArray type="Int32" Name="connectivity" NumberOfComponents="1"
format="appended" offset="116932" />
        <DataArray type="Int32" Name="offsets"      NumberOfComponents="1"
format="appended" offset="372936" />
        <DataArray type="UInt8" Name="types"        NumberOfComponents="1"
format="appended" offset="404940" />
      </Cells>
      <CellData>
        <DataArray type="Int32" Name="Rank" NumberOfComponents="1"
format="appended" offset="408944" />
      </CellData>
      <PointData>
        <DataArray type="Float64" Name="Vec_0x37c89c0_4Field_0.0"
NumberOfComponents="1" format="appended" offset="424948" />
      </PointData>
    </Piece>
    <Piece NumberOfPoints="4872" NumberOfCells="4000">
      <Points>
        <DataArray type="Float64" Name="Position" NumberOfComponents="3"
format="appended" offset="463928" />
      </Points>
      <Cells>
        <DataArray type="Int32" Name="connectivity" NumberOfComponents="1"
format="appended" offset="580860" />
        <DataArray type="Int32" Name="offsets"      NumberOfComponents="1"
format="appended" offset="836864" />
        <DataArray type="UInt8" Name="types"        NumberOfComponents="1"
format="appended" offset="868868" />
      </Cells>
      <CellData>
        <DataArray type="Int32" Name="Rank" NumberOfComponents="1"
format="appended" offset="872872" />
      </CellData>
      <PointData>
        <DataArray type="Float64" Name="Vec_0x37c89c0_4Field_0.0"
NumberOfComponents="1" format="appended" offset="888876" />
      </PointData>
    </Piece>
  </UnstructuredGrid>
  <AppendedData encoding="raw">


Thanks,
Mike


> On Sun, Feb 12, 2023 at 6:15 PM Mike Michell <mi.mike1021 at gmail.com>
> wrote:
>
>> Dear PETSc team,
>>
>> I am a user of PETSc with Fortran. My code uses DMPlex to handle dm
>> object. To print out output variable and mesh connectivity, I use VecView()
>> by defining PetscSection on that dm and borrow a vector. The type of the
>> viewer is set to PETSCVIEWERVTK.
>>
>> With 32bit indices, the above work flow has no issue. However, if PETSc
>> is configured with 64bit indices, my output .vtu file has an error if I
>> open the file with visualization tools, such as Paraview or Tecplot, saying
>> that:
>> "Cannot read cell connectivity from Cells in piece 0 because the
>> "offsets" array is not monotonically increasing or starts with a value
>> other than 0."
>>
>> If I open the .vtu file from terminal, I can see such a line:
>> ...
>> <DataArray type="Int32" Name="connectivity" NumberOfComponents="1"
>> format="appended" offset="580860" />
>> ...
>>
>> I expected "DataArray type="Int64", since the PETSc has 64bit indices.
>> Could I get recommendations that I need to check to resolve the issue?
>>
>
> This is probably a bug. We will look at it.
>
> Jed, I saw that Int32 is hardcoded in plexvtu.c, but sizeof(PetscInt) is
> used to calculate the offset, which looks inconsistent. Can you take a look?
>
>   Thanks,
>
>      Matt
>
>
>> Thanks,
>> Mike
>>
>
>
> --
> 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/>
>
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