Sorting a vector

[Matthew Knepley]

On Tue, Jun 16, 2009 at 5:38 AM, tog <guillaume.alleon at gmail.com> wrote:

> Hi there
>
> This is a kind of newbie question :)
> I have a vector which is the solution of my simulation, I want then to
> extract the p indices corresponding to the p biggest values in my vector. Is
> there a way to do this with PETSc ?


You can get p=1 with VecMax().


>
> What if I want to sort my vector to get the indices in ascending order of
> their values ?


The p=2+ and permutation cases are sophisticated in parallel and not
present. In serial, you can use
VecGetArray() and PetscSortReal()/SortRealWithPermutation().

  Matt


>
> Thanks
> Guillaume
>
-- 
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
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