[petsc-users] Question Regarding Duplicate Indices in VecSetValues().

[Mark Adams]

INSERT_VALUES is clearly an error, but we can't check that easily so you
will probably just get the last value, and ADD_VALUES should work.

Mark

On Tue, Jan 14, 2025 at 8:20 AM Venkata Narayana Sarma Dhavala <
dhavala at udel.edu> wrote:

> Dear PETSc Development Team,
>
> I hope this message finds you well. I am currently working with the
> VecSetValues() function in PETSc, and I have a question regarding its
> behavior when there are duplicate indices in the input array.
>
> PetscErrorCode VecSetValues(Vec x, PetscInt ni, const PetscInt ix[], const
> PetscScalar y[], InsertMode iora)
>
> Specifically, what is the expected behavior if the ix[] array passed to
> VecSetValues() contains duplicate indices? Does the function overwrite the
> value at those indices, or does it handle duplicates differently depending
> on the insert mode (INSERT_VALUES or ADD_VALUES)?
>
> I would greatly appreciate any clarification on this matter, as it will
> help me better understand how to manage values when working with
> potentially repeated indices in the input.
>
> Thank you for your time and assistance.
>
> Best regards,
>
> Narayana Dhavala.
>
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