[petsc-users] Use block Jacobi preconditioner with SNES

[Ali Reza Khaz'ali]

Hi,

I am trying to use block Jacobi preconditioner in SNES (SNESNEWTONLS). 
However, PCBJacobiGetSubKSP function returns an error stating "Object is 
in wrong state, Must call KSPSetUp() or PCSetUp() first". When I add 
KSPSetUp, I got and error from them as: "Must call 
DMShellSetGlobalVector() or DMShellSetCreateGlobalVector()", and if 
PCSetUp is added, "Object is in wrong state, Matrix must be set first" 
error is printed.

Below is a part of my code. It is run serially. Any help is much 
appreciated.

     ierr = SNESGetKSP(snes, &Petsc_ksp);
     CHKERRQ(ierr);
     ierr = KSPGetPC(Petsc_ksp, &Petsc_pc);
     CHKERRQ(ierr);
     ierr = KSPSetTolerances(Petsc_ksp, 1.e-3, 1e-3, PETSC_DEFAULT, 20000);
     CHKERRQ(ierr);
     ierr = SNESSetTolerances(snes, 1e-1, 1e-1, 1e-1, 2000, 2000);
     CHKERRQ(ierr);
     ierr = SNESSetType(snes, SNESNEWTONLS);
     CHKERRQ(ierr);
     ierr = KSPSetType(Petsc_ksp, KSPGMRES);
     CHKERRQ(ierr);
     ierr = PCSetType(Petsc_pc, PCBJACOBI);
     CHKERRQ(ierr);
     ierr = PCSetType(Petsc_pc, PCBJACOBI);
     CHKERRQ(ierr);
     ierr = PCBJacobiSetTotalBlocks(Petsc_pc, 2*Nx*Ny*Nz, SadeqSize);
     CHKERRQ(ierr);

     SNESSetUp(snes);
     CHKERRQ(ierr);
     ierr = PCBJacobiGetSubKSP(Petsc_pc, &nLocal, &Firstly, &subKSP);
     CHKERRQ(ierr);

     for (i = 0; i < nLocal; i++) {
         ierr = KSPGetPC(subKSP[i], &SubPc);
         CHKERRQ(ierr);
         ierr = PCSetType(SubPc, PCLU);
         CHKERRQ(ierr);
         ierr = PCFactorSetMatSolverPackage(SubPc, "mkl_pardiso");
         CHKERRQ(ierr);
         ierr = KSPSetType(subKSP[i], KSPPREONLY);
         CHKERRQ(ierr);
         ierr = KSPSetTolerances(subKSP[i], 1.e-6, PETSC_DEFAULT, 
PETSC_DEFAULT, PETSC_DEFAULT);
         CHKERRQ(ierr);
     }
     ierr = SNESSolve(snes, NULL, Petsc_X);
     CHKERRQ(ierr);



-- 
Ali Reza Khaz’ali
Assistant Professor of Petroleum Engineering,
Department of Chemical Engineering
Isfahan University of Technology
Isfahan, Iran