Running squential and parallel linear solver in the same code?

[Barry Smith]

  Ben,

   You can use -pc_type redundant -redundant_pc_type lu to solve the 
linear system with a sequential LU to test if that improves the situation.

Likely your generation of the matrix on 2 processes is wrong, you can run
with -mat_view on a small problem with both 1 and 2 processes and see if 
they are the same in both cases.

  I don't think what you propose to do below makes sense,

   Barry


On Tue, 23 Jan 2007, Ben Tay wrote:

> Hi,
> 
> In my MPI CFD code, I have to solve 2 linear eqns - momentum and poisson
> eqn. There's some error in the code and I don't know which one causes the
> error. May I know if it is possible to solve 1 eqn in sequential mode while
> the other in MPI to pinpoint the error since my code works ok in a
> sequential mode.
> 
> I tried to use this for one of the eqn:
> 
> 
> call
> MatCreateSeqAIJ(PETSC_COMM_SELF,size_x*size_y,size_x*size_y,9,PETSC_NULL_INTEGER,A_mat,ierr)
> 
> call VecCreateSeq(PETSC_COMM_SELF,size_x*size_y,b_rhs,ierr)
> 
> but there's error.
> 
> Thank you.
>