[petsc-users] SuperLU_4.0 with petsc-3.1-p3 - flipped output in KSPSolve.

[Hong Zhang]

Chetan:

Move
ierr = KSPSetFromOptions(ksp); CHKERRQ(ierr);

right before
ierr = KSPSolve()
and run your code with
-pc_type lu -pc_factor_mat_solver_package superlu

I got correct answer.
Attached is my modified code.

Hong
>
> I have a small code that solves a 3x3 system with and without
> SuperLU.  If SuperLU is used, vectors x and b (in A x = b) come
> out flipped after KSPSolve.  Am I doing something stupid?  The two
> outputs, the code, and the configure command are pasted below.
>
> Thanks,
>
> Chetan
>
> --------------------------------------------------------------------------
>
> Run with SuperLU:
>
> ~> lu_test -pc_factor_mat_solver_package superlu
> x before solve
> -10
> -10
> -10
> b before solve
> 200
> 200
> 200
> x after solve
> 200
> 200
> 200
> b after solve
> 0.2
> 0.2
> 0.2
>
> --------------------------------------------------------------------------
>
> Run without SuperLU (default KSP, PC options)
>
> ~> lu_test
> x before solve
> -10
> -10
> -10
> b before solve
> 200
> 200
> 200
> x after solve
> 0.2
> 0.2
> 0.2
> b after solve
> 200
> 200
> 200
>
> --------------------------------------------------------------------------
>
> Program:
>
> int main(int argc, char* argv[])
> {
>    PetscErrorCode ierr;
>
>    ierr = PetscInitialize(&argc, &argv, PETSC_NULL, PETSC_NULL);
> CHKERRQ(ierr);
>
>    Mat A;
>    ierr = MatCreateSeqAIJ(PETSC_COMM_SELF, 3, 3, 1, PETSC_NULL, &A);
> CHKERRQ(ierr);
>    ierr = MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY);
>    ierr = MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY);
>
>    ierr = MatShift(A, 1000); CHKERRQ(ierr);
>
>    Vec x, b;
>    ierr = VecCreateSeq(PETSC_COMM_SELF, 3, &x); CHKERRQ(ierr);
>    ierr = VecShift(x, -10); CHKERRQ(ierr);
>
>    ierr = VecCreateSeq(PETSC_COMM_SELF, 3, &b); CHKERRQ(ierr);
>    ierr = VecShift(b, 200); CHKERRQ(ierr);
>
>    KSP ksp;
>    ierr = KSPCreate(PETSC_COMM_SELF, &ksp); CHKERRQ(ierr);
>    ierr = KSPSetFromOptions(ksp); CHKERRQ(ierr);
>
>    printf("x before solve\n");
>    ierr = VecView(x, PETSC_VIEWER_STDOUT_SELF); CHKERRQ(ierr);
>    printf("b before solve\n");
>    ierr = VecView(b, PETSC_VIEWER_STDOUT_SELF); CHKERRQ(ierr);
>
>    ierr = KSPSetOperators(ksp, A, A, SAME_NONZERO_PATTERN); CHKERRQ(ierr);
>    ierr = KSPSolve(ksp, b, x); CHKERRQ(ierr);
>
>    printf("x after solve\n");
>    ierr = VecView(x, PETSC_VIEWER_STDOUT_SELF); CHKERRQ(ierr);
>    printf("b after solve\n");
>    ierr = VecView(b, PETSC_VIEWER_STDOUT_SELF); CHKERRQ(ierr);
>
>    ierr = PetscFinalize(); CHKERRQ(ierr);
> }
>
> --------------------------------------------------------------------------
>
> configure command:
>
> python ./config/configure.py -with-clanguage=C++ -with-debugging=no
> --with-gnu-compilers=1 --with-mpi=1 --with-umfpack=1 --with-superlu=1
> --with-hypre=1 --download-umfpack=1 --download-superlu=1
> --download-hypre=1 --with-mumps=1 --download-mumps=1 --with-parmetis=1
> --download-parmetis=1 --with-scalapack=1 --download-scalapack=1
> --with-blacs=1 --download-blacs=1 -with-c-support=1
>
> --------------------------------------------------------------------------
>
>
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