static char help[]= "Test PetscSFCreateByMatchingIndices\n\n";

#include <petsc.h>
#include <petscsf.h>

/* Test PetscSFCreateByMatchingIndices.

testnum 0:

  rank             : 0            1            2
  numRootIndices   : 3            1            1
  rootIndices      : [1 0 2]      [3]          [3]
  rootLocalOffset  : 100          200          300
  layout           : [0 1]        [2]          [3]
  numLeafIndices   : 1            1            2
  leafIndices      : [0]          [2]          [0 3]
  leafLocalOffset  : 400          500          600

would build the following SF:

  [0] 400 <- (0,101)
  [1] 500 <- (0,102)
  [2] 600 <- (0,101)
  [2] 601 <- (2,300)

testnum 1:

  rank             : 0               1               2
  numRootIndices   : 3               1               1
  rootIndices      : [1 0 2]         [3]             [3]
  rootLocalOffset  : 100             200             300
  layout           : [0 1]           [2]             [3]
  numLeafIndices   : numRootIndices  numRootIndices  numRootIndices
  leafIndices      : rootIndices     rootIndices     rootIndices
  leafLocalOffset  : rootLocalOffset rootLocalOffset rootLocalOffset

would build the following SF:

  [1] 200 <- (2,300)

testnum 2:

  No one claims ownership of global index 1, but no one needs it.

  rank             : 0            1            2
  numRootIndices   : 2            1            1
  rootIndices      : [0 2]        [3]          [3]
  rootLocalOffset  : 100          200          300
  layout           : [0 1]        [2]          [3]
  numLeafIndices   : 1            1            2
  leafIndices      : [0]          [2]          [0 3]
  leafLocalOffset  : 400          500          600

would build the following SF:

  [0] 400 <- (0,100)
  [1] 500 <- (0,101)
  [2] 600 <- (0,100)
  [2] 601 <- (2,300)

*/

int main(int argc, char **argv)
{
  PetscSF         sf;
  PetscLayout     layout;
  PetscInt        N, n;
  PetscInt        nA=-1, *A, offsetA=-1;
  PetscInt        nB=-1, *B, offsetB=-1;
  PetscMPIInt     size, rank;
  PetscInt        testnum;
  PetscErrorCode  ierr;

  ierr = PetscInitialize(&argc,&argv,NULL,help);if (ierr) return ierr;
  ierr = PetscOptionsGetInt(NULL,NULL, "-testnum", &testnum, NULL);CHKERRQ(ierr);
  ierr = MPI_Comm_size(PETSC_COMM_WORLD,&size);CHKERRMPI(ierr);
  ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRMPI(ierr);
  if (size != 3) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Must run with 3 MPI processes");

  switch (testnum) {
  case 0:
    N = 4;
    n = PETSC_DECIDE;
    switch (rank) {
    case 0: nA = 3; offsetA = 100; nB = 1; offsetB = 400; break;
    case 1: nA = 1; offsetA = 200; nB = 1; offsetB = 500; break;
    case 2: nA = 1; offsetA = 300; nB = 2; offsetB = 600; break;
    default: SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Must run with 3 MPI processes");
    }
    ierr = PetscMalloc1(nA, &A);CHKERRQ(ierr);
    ierr = PetscMalloc1(nB, &B);CHKERRQ(ierr);
    switch (rank) {
    case 0:
      A[0] = 1; A[1] = 0; A[2] = 2;
      B[0] = 0;
      break;
    case 1:
      A[0] = 3;
      B[0] = 2;
      break;
    case 2:
      A[0] = 3;
      B[0] = 0; B[1] = 3;
      break;
    default: SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Must run with 3 MPI processes");
    }
    break;
  case 1:
    N = 4;
    n = PETSC_DECIDE;
    switch (rank) {
    case 0: nA = 3; offsetA = 100; break;
    case 1: nA = 1; offsetA = 200; break;
    case 2: nA = 1; offsetA = 300; break;
    default: SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Must run with 3 MPI processes");
    }
    ierr = PetscMalloc1(nA, &A);CHKERRQ(ierr);
    switch (rank) {
    case 0:
      A[0] = 1; A[1] = 0; A[2] = 2;
      break;
    case 1:
      A[0] = 3;
      break;
    case 2:
      A[0] = 3;
      break;
    default: SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Must run with 3 MPI processes");
    }
    nB = nA;
    B = A;
    offsetB = offsetA;
    break;
  case 2:
    N = 4;
    n = PETSC_DECIDE;
    switch (rank) {
    case 0: nA = 2; offsetA = 100; nB = 1; offsetB = 400; break;
    case 1: nA = 1; offsetA = 200; nB = 1; offsetB = 500; break;
    case 2: nA = 1; offsetA = 300; nB = 2; offsetB = 600; break;
    default: SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Must run with 3 MPI processes");
    }
    ierr = PetscMalloc1(nA, &A);CHKERRQ(ierr);
    ierr = PetscMalloc1(nB, &B);CHKERRQ(ierr);
    switch (rank) {
    case 0:
      A[0] = 0; A[1] = 2;
      B[0] = 0;
      break;
    case 1:
      A[0] = 3;
      B[0] = 2;
      break;
    case 2:
      A[0] = 3;
      B[0] = 0; B[1] = 3;
      break;
    default: SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_WRONG_MPI_SIZE,"Must run with 3 MPI processes");
    }
    break;
  }
  ierr = PetscLayoutCreate(PETSC_COMM_WORLD, &layout);CHKERRQ(ierr);
  ierr = PetscLayoutSetSize(layout, N);CHKERRQ(ierr);
  ierr = PetscLayoutSetLocalSize(layout, n);CHKERRQ(ierr);
  ierr = PetscLayoutSetBlockSize(layout, 1);CHKERRQ(ierr);
  ierr = PetscSFCreateByMatchingIndices(layout, nA, A, NULL, offsetA, nB, B, NULL, offsetB, NULL, &sf);CHKERRQ(ierr);
  ierr = PetscLayoutDestroy(&layout);CHKERRQ(ierr);
  ierr = PetscFree(A);CHKERRQ(ierr);
  if (testnum != 1) {ierr = PetscFree(B);CHKERRQ(ierr);}
  ierr = PetscObjectSetName((PetscObject)sf, "sf");CHKERRQ(ierr);
  ierr = PetscSFView(sf, NULL);CHKERRQ(ierr);
  ierr = PetscSFDestroy(&sf);CHKERRQ(ierr);

  ierr = PetscFinalize();
  return ierr;
}

/*TEST

  test:
    suffix: 0
    nsize: 3
    args: -testnum 0

  test:
    suffix: 1
    nsize: 3
    args: -testnum 1

  test:
    suffix: 2
    nsize: 3
    args: -testnum 2

TEST*/