xref: /petsc/src/ksp/pc/tests/ex7.c (revision 732aec7a18f2199fb53bb9a2f3aef439a834ce31)

static char help[] = "Tests MatILUFactorSymbolic() on matrix with missing diagonal.\n\n";

#include <petscmat.h>
#include <petscpc.h>

int main(int argc, char **args)
{
  Mat         C, A;
  PetscInt    i, j;
  PetscScalar v;
  PC          pc;
  Vec         xtmp;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &args, NULL, help));
  PetscCall(MatCreate(PETSC_COMM_WORLD, &C));
  PetscCall(MatSetSizes(C, PETSC_DECIDE, PETSC_DECIDE, 3, 3));
  PetscCall(MatSetFromOptions(C));
  PetscCall(MatSetUp(C));
  PetscCall(VecCreateSeq(PETSC_COMM_WORLD, 3, &xtmp));
  i = 0;
  j = 0;
  v = 4;
  PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
  i = 0;
  j = 2;
  v = 1;
  PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
  i = 1;
  j = 0;
  v = 1;
  PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
  i = 1;
  j = 1;
  v = 4;
  PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));
  i = 2;
  j = 1;
  v = 1;
  PetscCall(MatSetValues(C, 1, &i, 1, &j, &v, INSERT_VALUES));

  PetscCall(MatAssemblyBegin(C, MAT_FINAL_ASSEMBLY));
  PetscCall(MatAssemblyEnd(C, MAT_FINAL_ASSEMBLY));

  PetscCall(MatView(C, PETSC_VIEWER_STDOUT_WORLD));
  PetscCall(PCCreate(PETSC_COMM_WORLD, &pc));
  PetscCall(PCSetFromOptions(pc));
  PetscCall(PCSetOperators(pc, C, C));
  PetscCall(PCSetUp(pc));
  PetscCall(PCFactorGetMatrix(pc, &A));
  PetscCall(MatView(A, PETSC_VIEWER_STDOUT_WORLD));

  PetscCall(PCDestroy(&pc));
  PetscCall(VecDestroy(&xtmp));
  PetscCall(MatDestroy(&C));

  PetscCall(PetscFinalize());
  return 0;
}