[petsc-users] Erro in solution

[Danesh Daroui]

Dear PETSc users,

I have recently started to use PETSc in our code. As the first try, I
assemble the matrix row by row and then put each non-zero element in
each row into PETSc matrix. Then I start to solve the equation. I use
PETSc on a multi-core machine, so I will not use MPI in my program. I
compiled PETSc without MPI. The PETSc parts of my code are:


        Mat Mp;
        Vec xp, bp;
        KSP ksp;
        PetscErrorCode ierr;

        ierr=MatCreate(PETSC_COMM_WORLD, &Mp);
        ierr=MatSetSizes(Mp, Msize, Msize, Msize, Msize);
        ierr=MatSetType(Mp, MATSEQAIJ);
        ierr=MatSetUp(Mp);

        ierr=VecCreate(PETSC_COMM_WORLD, &xp);
        ierr=VecSetSizes(xp, Msize, Msize);
        ierr=VecSetFromOptions(xp);

        ierr=VecCreate(PETSC_COMM_WORLD, &bp);
        ierr=VecSetSizes(bp, Msize, Msize);
        ierr=VecSetFromOptions(bp);

	.
	.
	.

	// each non zero element of row "i" and column "k" is put in 
	// PETSc matrix
	if (M_row[k]!=0.0)
		ierr=MatSetValues(Mp, 1, &i, 1, &k, &M_row[k],
					ADD_VALUES);


	ierr=MatAssemblyBegin(Mp, MAT_FINAL_ASSEMBLY);
	ierr=MatAssemblyEnd(Mp, MAT_FINAL_ASSEMBLY);

	.
	.
	.

	// copy right-hand-side to PETSc vector
	for (int i=0; i<Msize; ++i)
		VecSetValue(bp, i, b[i], INSERT_VALUES);

	VecAssemblyBegin(bp);
	VecAssemblyEnd(bp);

	ierr=KSPCreate(PETSC_COMM_WORLD, &ksp);
	ierr=KSPSetOperators(ksp, Mp, Mp, DIFFERENT_NONZERO_PATTERN);
	ierr=KSPSetTolerances(ksp, 1.e-2/Msize, 1.e-50, PETSC_DEFAULT, 
				PETSC_DEFAULT);
	ierr=KSPSetFromOptions(ksp);
	ierr=KSPSolve(ksp, bp, xp);





The problem is that whenever I run the code I get following output:




[0]PETSC ERROR: --------------------- Error Message
------------------------------------
[0]PETSC ERROR: Object is in wrong state!
[0]PETSC ERROR: Matrix is missing diagonal entry 309!
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: Petsc Release Version 3.1.0, Patch 8, Thu Mar 17
13:37:48 CDT 2011
[0]PETSC ERROR: See docs/changes/index.html for recent updates.
[0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
[0]PETSC ERROR: See docs/index.html for manual pages.
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: Unknown Name on a linux-gnu named linux-sclt.site by dan
Fri May  6 19:34:19 2011
[0]PETSC ERROR: Libraries linked
from /home/danesh/petsc-3.1-p8/linux-gnu-intel/lib
[0]PETSC ERROR: Configure run at Fri May  6 15:50:26 2011
[0]PETSC ERROR: Configure options PETSC_ARCH=linux-gnu-intel
--with-scalar-type=complex --with-clanguage=c++ --with-mpi=0
--with-cc=icc --with-fc=gfortran --with-cxx=icpc
--with-blas-lapack-dir=/home/danesh/intel/mkl/lib/intel64/
[0]PETSC ERROR:
------------------------------------------------------------------------
[0]PETSC ERROR: MatILUFactorSymbolic_SeqAIJ_ilu0() line 1627 in
src/mat/impls/aij/seq/aijfact.c
[0]PETSC ERROR: MatILUFactorSymbolic_SeqAIJ() line 1731 in
src/mat/impls/aij/seq/aijfact.c
[0]PETSC ERROR: MatILUFactorSymbolic() line 5464 in
src/mat/interface/matrix.c
[0]PETSC ERROR: PCSetUp_ILU() line 204 in
src/ksp/pc/impls/factor/ilu/ilu.c
[0]PETSC ERROR: PCSetUp() line 795 in src/ksp/pc/interface/precon.c
[0]PETSC ERROR: KSPSetUp() line 237 in src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: KSPSolve() line 353 in src/ksp/ksp/interface/itfunc.c



I am sure that the matrix is correct and the system is not singular
because the system can be solved using LAPACK's direct solver. I
probably format the PETSc matrix incorrectly or some PETSc parameters
are wrong. I would appreciate if you give me any clue about possible
problem(s).

Regards,

Danesh