static char help[] = "Tests the use of MatZeroRows() for parallel matrices.\n\
This example also tests the use of MatDuplicate() for both MPIAIJ and MPIBAIJ matrices";

#include <petscmat.h>

extern PetscErrorCode TestMatZeroRows_Basic(Mat, IS, PetscScalar);
extern PetscErrorCode TestMatZeroRows_with_no_allocation(Mat, IS, PetscScalar);

int main(int argc, char **args)
{
  Mat         A;
  PetscInt    i, j, m = 3, n, Ii, J, Imax;
  PetscMPIInt rank, size;
  PetscScalar v, diag = -4.0;
  IS          is;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &args, NULL, help));
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
  n = 2 * size;

  /* create A Square matrix for the five point stencil,YET AGAIN*/
  PetscCall(MatCreate(PETSC_COMM_WORLD, &A));
  PetscCall(MatSetSizes(A, PETSC_DECIDE, PETSC_DECIDE, m * n, m * n));
  PetscCall(MatSetFromOptions(A));
  PetscCall(MatSetUp(A));
  for (i = 0; i < m; i++) {
    for (j = 2 * rank; j < 2 * rank + 2; j++) {
      v  = -1.0;
      Ii = j + n * i;
      if (i > 0) {
        J = Ii - n;
        PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
      }
      if (i < m - 1) {
        J = Ii + n;
        PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
      }
      if (j > 0) {
        J = Ii - 1;
        PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
      }
      if (j < n - 1) {
        J = Ii + 1;
        PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
      }
      v = 4.0;
      PetscCall(MatSetValues(A, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
    }
  }
  PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
  PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));

  /* Create AN IS required by MatZeroRows() */
  Imax = n * rank;
  if (Imax >= n * m - m - 1) Imax = m * n - m - 1;
  PetscCall(ISCreateStride(PETSC_COMM_SELF, m, Imax, 1, &is));

  PetscCall(TestMatZeroRows_Basic(A, is, 0.0));
  PetscCall(TestMatZeroRows_Basic(A, is, diag));

  PetscCall(TestMatZeroRows_with_no_allocation(A, is, 0.0));
  PetscCall(TestMatZeroRows_with_no_allocation(A, is, diag));

  PetscCall(MatDestroy(&A));

  /* Now Create a rectangular matrix with five point stencil (app)
   n+size is used so that this dimension is always divisible by size.
   This way, we can always use bs = size for any number of procs */
  PetscCall(MatCreate(PETSC_COMM_WORLD, &A));
  PetscCall(MatSetSizes(A, PETSC_DECIDE, PETSC_DECIDE, m * n, m * (n + size)));
  PetscCall(MatSetFromOptions(A));
  PetscCall(MatSetUp(A));
  for (i = 0; i < m; i++) {
    for (j = 2 * rank; j < 2 * rank + 2; j++) {
      v  = -1.0;
      Ii = j + n * i;
      if (i > 0) {
        J = Ii - n;
        PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
      }
      if (i < m - 1) {
        J = Ii + n;
        PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
      }
      if (j > 0) {
        J = Ii - 1;
        PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
      }
      if (j < n + size - 1) {
        J = Ii + 1;
        PetscCall(MatSetValues(A, 1, &Ii, 1, &J, &v, INSERT_VALUES));
      }
      v = 4.0;
      PetscCall(MatSetValues(A, 1, &Ii, 1, &Ii, &v, INSERT_VALUES));
    }
  }
  PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
  PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));

  PetscCall(TestMatZeroRows_Basic(A, is, 0.0));
  PetscCall(TestMatZeroRows_Basic(A, is, diag));

  PetscCall(MatDestroy(&A));
  PetscCall(ISDestroy(&is));
  PetscCall(PetscFinalize());
  return 0;
}

PetscErrorCode TestMatZeroRows_Basic(Mat A, IS is, PetscScalar diag)
{
  Mat       B;
  PetscBool keepnonzeropattern;

  /* Now copy A into B, and test it with MatZeroRows() */
  PetscFunctionBeginUser;
  PetscCall(MatDuplicate(A, MAT_COPY_VALUES, &B));

  PetscCall(PetscOptionsHasName(NULL, NULL, "-keep_nonzero_pattern", &keepnonzeropattern));
  if (keepnonzeropattern) PetscCall(MatSetOption(B, MAT_KEEP_NONZERO_PATTERN, PETSC_TRUE));

  PetscCall(MatZeroRowsIS(B, is, diag, 0, 0));
  PetscCall(MatView(B, PETSC_VIEWER_STDOUT_WORLD));
  PetscCall(MatDestroy(&B));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode TestMatZeroRows_with_no_allocation(Mat A, IS is, PetscScalar diag)
{
  Mat B;

  /* Now copy A into B, and test it with MatZeroRows() */
  PetscFunctionBeginUser;
  PetscCall(MatDuplicate(A, MAT_COPY_VALUES, &B));
  /* Set this flag after assembly. This way, it affects only MatZeroRows() */
  PetscCall(MatSetOption(B, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_TRUE));

  PetscCall(MatZeroRowsIS(B, is, diag, 0, 0));
  PetscCall(MatView(B, PETSC_VIEWER_STDOUT_WORLD));
  PetscCall(MatDestroy(&B));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*TEST

   test:
      nsize: 2
      filter: grep -v " MPI process"

   test:
      suffix: 2
      nsize: 3
      args: -mat_type mpibaij -mat_block_size 3
      filter: grep -v " MPI process"

   test:
      suffix: 3
      nsize: 3
      args: -mat_type mpiaij -keep_nonzero_pattern
      filter: grep -v " MPI process"

   test:
      suffix: 4
      nsize: 3
      args: -keep_nonzero_pattern -mat_type mpibaij -mat_block_size 3
      filter: grep -v " MPI process"

   test:
      requires: !defined(PETSC_HAVE_THREADSAFETY)
      suffix: 5
      nsize: 3
      args: -mat_type mpibaij -mat_block_size 3 -mat_view
      filter: grep -v " MPI process"

TEST*/