Hi, I need to compute the permutations to sort scalar values of a Vec object in decreasing order. I've been developing on a single process for now, using VecGetArrayRead() to extract the values and PetscSortRealWithPermutation() to get the permutations.
I would like to run the code on multiple processes. From these links, I can see it's an issue : https://lists.mcs.anl.gov/pipermail/petsc-users/2013-November/019628.html https://lists.mcs.anl.gov/pipermail/petsc-users/2009-June/004621.html One work around I've been considering : get the max scalar value using VecMax() ; compute a scaling factor that makes this max value equals the largest integer value tolerated by PetscInt ; scale all values of Vec and convert them to integers ; use PetscParallelSortInt() ; inverse the scaling on (now sorted) integers values and convert them back to scalars. This is only a patch really, the main issues being : (1) I would get a sorted Vec, not the permutations and (2) there would be a lost of information when converting scalars to int values. Isn't there a way to parallel sort real values using Petsc? Thank you very much! Antoine Côté
