[petsc-users] Row Orderings of Mat and Vec

[Hui Zhang]

Suppose using MatCreate() and MatSetSizes() we obtain a Mat A, and then
using VecCreate() and VecSetSizes() with the same rows' arguments as A
we obtain a Vec b.  Let A_i (b_i) consists of the rows owned by processor i.

Can I believe that under the ordering of petsc, the following equality holds,
A= [A_0
    A_1
    ...
    A_N],
b= [b_0
    b_1
    ...
    b_N],
i.e. A_i, b_i with smaller i--the processor number goes first?  

My question comes from assembly of linear system.  Suppose under my application 
ordering(AO) the system is Ax=b.  I can get an AO from A using 

      MatGetOwnershipRanges(A,&Istart,&Iend);
      AOCreateBasic( -, -,app_ind, Istart..Iend, &ao_1);

and assemble A.  Under the petsc ordering, A becomes P_1*A mathematically, with
P_1 the permutation corresponding to ao_1.  In a similar way, we have that b 
becomes P_2 b under the petsc ordering.  I want to make sure P_1 and P_2 are
the same so arises my question.

Thanks a lot!
Hui