Hi, I'm was sorting an array which that has duplicate entries: (x = [39 9 19 39 29]). I noticed that for duplicate entries after sorting, the index returned are not in ascending. The example below will explain this further. Here is the code snippet: ============================================ do ii=1,5 index(ii) = ii endo index = index -1 call PetscSortIntWithPermutation( 5, x, index, ierr) index = index + 1 do ii=1,5 write(*,*), x(ii), index(ii), x(index(ii)) enddo ============================================ Output: 39 2 9 9 3 19 19 5 29 39 4 39 29 1 39 Output (Expected by me, similar to MATLAB output): Note the difference in the index(4) and index(5) values 39 2 9 9 3 19 19 5 29 39 1 39 29 4 39 I tired using PetscSortIntWithArray and go similar result. I was wondering if there is a sorting option that can get me the output which I'm expecting. The only way around I came up for this was to look at the index(:) entries that correspond to duplicate values and sort them again. -Gautam.