xref: /petsc/src/dm/tutorials/swarm_ex1.c (revision 4e8208cbcbc709572b8abe32f33c78b69c819375)

#include "petscis.h"
#include "petscsys.h"
#include "petscsystypes.h"
#include "petscvec.h"
static char help[] = "Tests DMSwarm\n\n";

#include <petscdm.h>
#include <petscdmda.h>
#include <petscdmswarm.h>

PETSC_EXTERN PetscErrorCode DMSwarmCollect_General(DM, PetscErrorCode (*)(DM, void *, PetscInt *, PetscInt **), size_t, void *, PetscInt *);
PETSC_EXTERN PetscErrorCode DMSwarmCollect_DMDABoundingBox(DM, PetscInt *);

PetscErrorCode ex1_1(void)
{
  DM          dms;
  Vec         x;
  PetscMPIInt rank, size;
  PetscInt    p;

  PetscFunctionBegin;
  PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  PetscCheck(!(size > 1) || !(size != 4), PETSC_COMM_WORLD, PETSC_ERR_SUP, "Must be run with 4 MPI ranks");

  PetscCall(DMCreate(PETSC_COMM_WORLD, &dms));
  PetscCall(DMSetType(dms, DMSWARM));
  PetscCall(PetscObjectSetName((PetscObject)dms, "Particles"));

  PetscCall(DMSwarmInitializeFieldRegister(dms));
  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "viscosity", 1, PETSC_REAL));
  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "strain", 1, PETSC_REAL));
  PetscCall(DMSwarmFinalizeFieldRegister(dms));
  PetscCall(DMSwarmSetLocalSizes(dms, 5 + rank, 4));
  PetscCall(DMView(dms, PETSC_VIEWER_STDOUT_WORLD));

  {
    PetscReal *array;
    PetscCall(DMSwarmGetField(dms, "viscosity", NULL, NULL, (void **)&array));
    for (p = 0; p < 5 + rank; p++) array[p] = 11.1 + p * 0.1 + rank * 100.0;
    PetscCall(DMSwarmRestoreField(dms, "viscosity", NULL, NULL, (void **)&array));
  }

  {
    PetscReal *array;
    PetscCall(DMSwarmGetField(dms, "strain", NULL, NULL, (void **)&array));
    for (p = 0; p < 5 + rank; p++) array[p] = 2.0e-2 + p * 0.001 + rank * 1.0;
    PetscCall(DMSwarmRestoreField(dms, "strain", NULL, NULL, (void **)&array));
  }

  PetscCall(DMSwarmCreateGlobalVectorFromField(dms, "viscosity", &x));
  PetscCall(DMSwarmDestroyGlobalVectorFromField(dms, "viscosity", &x));

  PetscCall(DMSwarmVectorDefineField(dms, "strain"));
  PetscCall(DMCreateGlobalVector(dms, &x));
  PetscCall(VecDestroy(&x));

  {
    PetscInt *rankval;
    PetscInt  npoints[2], npoints_orig[2];

    PetscCall(DMSwarmGetLocalSize(dms, &npoints_orig[0]));
    PetscCall(DMSwarmGetSize(dms, &npoints_orig[1]));
    PetscCall(DMSwarmGetField(dms, DMSwarmField_rank, NULL, NULL, (void **)&rankval));
    if ((rank == 0) && (size > 1)) {
      rankval[0] = 1;
      rankval[3] = 1;
    }
    if (rank == 3) rankval[2] = 1;
    PetscCall(DMSwarmRestoreField(dms, DMSwarmField_rank, NULL, NULL, (void **)&rankval));
    PetscCall(DMSwarmMigrate(dms, PETSC_TRUE));
    PetscCall(DMSwarmGetLocalSize(dms, &npoints[0]));
    PetscCall(DMSwarmGetSize(dms, &npoints[1]));
    PetscCall(PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD, "rank[%d] before(%" PetscInt_FMT ",%" PetscInt_FMT ") after(%" PetscInt_FMT ",%" PetscInt_FMT ")\n", rank, npoints_orig[0], npoints_orig[1], npoints[0], npoints[1]));
    PetscCall(PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD));
  }
  {
    PetscCall(DMSwarmCreateGlobalVectorFromField(dms, "viscosity", &x));
    PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(DMSwarmDestroyGlobalVectorFromField(dms, "viscosity", &x));
  }
  {
    PetscCall(DMSwarmCreateGlobalVectorFromField(dms, "strain", &x));
    PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(DMSwarmDestroyGlobalVectorFromField(dms, "strain", &x));
  }

  PetscCall(DMDestroy(&dms));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode ex1_2(void)
{
  DM          dms;
  Vec         x;
  PetscMPIInt rank, size;
  PetscInt    p;

  PetscFunctionBegin;
  PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  PetscCall(DMCreate(PETSC_COMM_WORLD, &dms));
  PetscCall(DMSetType(dms, DMSWARM));
  PetscCall(PetscObjectSetName((PetscObject)dms, "Particles"));
  PetscCall(DMSwarmInitializeFieldRegister(dms));

  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "viscosity", 1, PETSC_REAL));
  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "strain", 1, PETSC_REAL));
  PetscCall(DMSwarmFinalizeFieldRegister(dms));
  PetscCall(DMSwarmSetLocalSizes(dms, 5 + rank, 4));
  PetscCall(DMView(dms, PETSC_VIEWER_STDOUT_WORLD));
  {
    PetscReal *array;
    PetscCall(DMSwarmGetField(dms, "viscosity", NULL, NULL, (void **)&array));
    for (p = 0; p < 5 + rank; p++) array[p] = 11.1 + p * 0.1 + rank * 100.0;
    PetscCall(DMSwarmRestoreField(dms, "viscosity", NULL, NULL, (void **)&array));
  }
  {
    PetscReal *array;
    PetscCall(DMSwarmGetField(dms, "strain", NULL, NULL, (void **)&array));
    for (p = 0; p < 5 + rank; p++) array[p] = 2.0e-2 + p * 0.001 + rank * 1.0;
    PetscCall(DMSwarmRestoreField(dms, "strain", NULL, NULL, (void **)&array));
  }
  {
    PetscInt *rankval;
    PetscInt  npoints[2], npoints_orig[2];

    PetscCall(DMSwarmGetLocalSize(dms, &npoints_orig[0]));
    PetscCall(DMSwarmGetSize(dms, &npoints_orig[1]));
    PetscCall(PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD, "rank[%d] before(%" PetscInt_FMT ",%" PetscInt_FMT ")\n", rank, npoints_orig[0], npoints_orig[1]));
    PetscCall(PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD));

    PetscCall(DMSwarmGetField(dms, "DMSwarm_rank", NULL, NULL, (void **)&rankval));

    if (rank == 1) rankval[0] = -1;
    if (rank == 2) rankval[1] = -1;
    if (rank == 3) {
      rankval[3] = -1;
      rankval[4] = -1;
    }
    PetscCall(DMSwarmRestoreField(dms, "DMSwarm_rank", NULL, NULL, (void **)&rankval));
    PetscCall(DMSwarmCollectViewCreate(dms));
    PetscCall(DMSwarmGetLocalSize(dms, &npoints[0]));
    PetscCall(DMSwarmGetSize(dms, &npoints[1]));
    PetscCall(PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD, "rank[%d] after(%" PetscInt_FMT ",%" PetscInt_FMT ")\n", rank, npoints[0], npoints[1]));
    PetscCall(PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD));

    PetscCall(DMSwarmCreateGlobalVectorFromField(dms, "viscosity", &x));
    PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(DMSwarmDestroyGlobalVectorFromField(dms, "viscosity", &x));

    PetscCall(DMSwarmCollectViewDestroy(dms));
    PetscCall(DMSwarmGetLocalSize(dms, &npoints[0]));
    PetscCall(DMSwarmGetSize(dms, &npoints[1]));
    PetscCall(PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD, "rank[%d] after_v(%" PetscInt_FMT ",%" PetscInt_FMT ")\n", rank, npoints[0], npoints[1]));
    PetscCall(PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD));

    PetscCall(DMSwarmCreateGlobalVectorFromField(dms, "viscosity", &x));
    PetscCall(VecView(x, PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(DMSwarmDestroyGlobalVectorFromField(dms, "viscosity", &x));
  }
  PetscCall(DMDestroy(&dms));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*
 splot "c-rank0.gp","c-rank1.gp","c-rank2.gp","c-rank3.gp"
*/
PetscErrorCode ex1_3(void)
{
  DM          dms;
  PetscMPIInt rank, size;
  PetscInt    is, js, ni, nj, overlap;
  DM          dmcell;

  PetscFunctionBegin;
  PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  overlap = 2;
  PetscCall(DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DMDA_STENCIL_BOX, 13, 13, PETSC_DECIDE, PETSC_DECIDE, 1, overlap, NULL, NULL, &dmcell));
  PetscCall(DMSetFromOptions(dmcell));
  PetscCall(DMSetUp(dmcell));
  PetscCall(DMDASetUniformCoordinates(dmcell, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0));
  PetscCall(DMDAGetCorners(dmcell, &is, &js, NULL, &ni, &nj, NULL));
  PetscCall(DMCreate(PETSC_COMM_WORLD, &dms));
  PetscCall(DMSetType(dms, DMSWARM));
  PetscCall(PetscObjectSetName((PetscObject)dms, "Particles"));
  PetscCall(DMSwarmSetCellDM(dms, dmcell));

  /* load in data types */
  PetscCall(DMSwarmInitializeFieldRegister(dms));
  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "viscosity", 1, PETSC_REAL));
  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "coorx", 1, PETSC_REAL));
  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "coory", 1, PETSC_REAL));
  PetscCall(DMSwarmFinalizeFieldRegister(dms));
  PetscCall(DMSwarmSetLocalSizes(dms, ni * nj * 4, 4));
  PetscCall(DMView(dms, PETSC_VIEWER_STDOUT_WORLD));

  /* set values within the swarm */
  {
    PetscReal   *array_x, *array_y;
    PetscInt     npoints, i, j, cnt;
    DMDACoor2d **LA_coor;
    Vec          coor;
    DM           dmcellcdm;

    PetscCall(DMGetCoordinateDM(dmcell, &dmcellcdm));
    PetscCall(DMGetCoordinates(dmcell, &coor));
    PetscCall(DMDAVecGetArray(dmcellcdm, coor, &LA_coor));
    PetscCall(DMSwarmGetLocalSize(dms, &npoints));
    PetscCall(DMSwarmGetField(dms, "coorx", NULL, NULL, (void **)&array_x));
    PetscCall(DMSwarmGetField(dms, "coory", NULL, NULL, (void **)&array_y));
    cnt = 0;
    for (j = js; j < js + nj; j++) {
      for (i = is; i < is + ni; i++) {
        PetscReal xp, yp;
        xp                   = PetscRealPart(LA_coor[j][i].x);
        yp                   = PetscRealPart(LA_coor[j][i].y);
        array_x[4 * cnt + 0] = xp - 0.05;
        if (array_x[4 * cnt + 0] < -1.0) array_x[4 * cnt + 0] = -1.0 + 1.0e-12;
        array_x[4 * cnt + 1] = xp + 0.05;
        if (array_x[4 * cnt + 1] > 1.0) array_x[4 * cnt + 1] = 1.0 - 1.0e-12;
        array_x[4 * cnt + 2] = xp - 0.05;
        if (array_x[4 * cnt + 2] < -1.0) array_x[4 * cnt + 2] = -1.0 + 1.0e-12;
        array_x[4 * cnt + 3] = xp + 0.05;
        if (array_x[4 * cnt + 3] > 1.0) array_x[4 * cnt + 3] = 1.0 - 1.0e-12;

        array_y[4 * cnt + 0] = yp - 0.05;
        if (array_y[4 * cnt + 0] < -1.0) array_y[4 * cnt + 0] = -1.0 + 1.0e-12;
        array_y[4 * cnt + 1] = yp - 0.05;
        if (array_y[4 * cnt + 1] < -1.0) array_y[4 * cnt + 1] = -1.0 + 1.0e-12;
        array_y[4 * cnt + 2] = yp + 0.05;
        if (array_y[4 * cnt + 2] > 1.0) array_y[4 * cnt + 2] = 1.0 - 1.0e-12;
        array_y[4 * cnt + 3] = yp + 0.05;
        if (array_y[4 * cnt + 3] > 1.0) array_y[4 * cnt + 3] = 1.0 - 1.0e-12;
        cnt++;
      }
    }
    PetscCall(DMSwarmRestoreField(dms, "coory", NULL, NULL, (void **)&array_y));
    PetscCall(DMSwarmRestoreField(dms, "coorx", NULL, NULL, (void **)&array_x));
    PetscCall(DMDAVecRestoreArray(dmcellcdm, coor, &LA_coor));
  }
  {
    PetscInt npoints[2], npoints_orig[2], ng;

    PetscCall(DMSwarmGetLocalSize(dms, &npoints_orig[0]));
    PetscCall(DMSwarmGetSize(dms, &npoints_orig[1]));
    PetscCall(PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD, "rank[%d] before(%" PetscInt_FMT ",%" PetscInt_FMT ")\n", rank, npoints_orig[0], npoints_orig[1]));
    PetscCall(PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(DMSwarmCollect_DMDABoundingBox(dms, &ng));

    PetscCall(DMSwarmGetLocalSize(dms, &npoints[0]));
    PetscCall(DMSwarmGetSize(dms, &npoints[1]));
    PetscCall(PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD, "rank[%d] after(%" PetscInt_FMT ",%" PetscInt_FMT ")\n", rank, npoints[0], npoints[1]));
    PetscCall(PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD));
  }
  {
    PetscReal *array_x, *array_y;
    PetscInt   npoints, p;
    FILE      *fp = NULL;
    char       name[PETSC_MAX_PATH_LEN];

    PetscCall(PetscSNPrintf(name, PETSC_MAX_PATH_LEN - 1, "c-rank%d.gp", rank));
    fp = fopen(name, "w");
    PetscCheck(fp, PETSC_COMM_SELF, PETSC_ERR_FILE_OPEN, "Cannot open file %s", name);
    PetscCall(DMSwarmGetLocalSize(dms, &npoints));
    PetscCall(DMSwarmGetField(dms, "coorx", NULL, NULL, (void **)&array_x));
    PetscCall(DMSwarmGetField(dms, "coory", NULL, NULL, (void **)&array_y));
    for (p = 0; p < npoints; p++) fprintf(fp, "%+1.4e %+1.4e %1.4e\n", array_x[p], array_y[p], (double)rank);
    PetscCall(DMSwarmRestoreField(dms, "coory", NULL, NULL, (void **)&array_y));
    PetscCall(DMSwarmRestoreField(dms, "coorx", NULL, NULL, (void **)&array_x));
    fclose(fp);
  }
  PetscCall(DMDestroy(&dmcell));
  PetscCall(DMDestroy(&dms));
  PetscFunctionReturn(PETSC_SUCCESS);
}

typedef struct {
  PetscReal cx[2];
  PetscReal radius;
} CollectZoneCtx;

PetscErrorCode collect_zone(DM dm, PetscCtx ctx, PetscInt *nfound, PetscInt **foundlist)
{
  CollectZoneCtx *zone = (CollectZoneCtx *)ctx;
  PetscInt        p, npoints;
  PetscReal      *array_x, *array_y, r2;
  PetscInt        p2collect, *plist;
  PetscMPIInt     rank;

  PetscFunctionBegin;
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  PetscCall(DMSwarmGetLocalSize(dm, &npoints));
  PetscCall(DMSwarmGetField(dm, "coorx", NULL, NULL, (void **)&array_x));
  PetscCall(DMSwarmGetField(dm, "coory", NULL, NULL, (void **)&array_y));

  r2        = zone->radius * zone->radius;
  p2collect = 0;
  for (p = 0; p < npoints; p++) {
    PetscReal sep2;

    sep2 = (array_x[p] - zone->cx[0]) * (array_x[p] - zone->cx[0]);
    sep2 += (array_y[p] - zone->cx[1]) * (array_y[p] - zone->cx[1]);
    if (sep2 < r2) p2collect++;
  }

  PetscCall(PetscMalloc1(p2collect + 1, &plist));
  p2collect = 0;
  for (p = 0; p < npoints; p++) {
    PetscReal sep2;

    sep2 = (array_x[p] - zone->cx[0]) * (array_x[p] - zone->cx[0]);
    sep2 += (array_y[p] - zone->cx[1]) * (array_y[p] - zone->cx[1]);
    if (sep2 < r2) {
      plist[p2collect] = p;
      p2collect++;
    }
  }
  PetscCall(DMSwarmRestoreField(dm, "coory", NULL, NULL, (void **)&array_y));
  PetscCall(DMSwarmRestoreField(dm, "coorx", NULL, NULL, (void **)&array_x));

  *nfound    = p2collect;
  *foundlist = plist;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode ex1_4(void)
{
  DM              dms;
  PetscMPIInt     rank, size;
  PetscInt        is, js, ni, nj, overlap, nn;
  DM              dmcell;
  CollectZoneCtx *zone;
  PetscReal       dx;

  PetscFunctionBegin;
  PetscCallMPI(MPI_Comm_size(PETSC_COMM_WORLD, &size));
  PetscCallMPI(MPI_Comm_rank(PETSC_COMM_WORLD, &rank));
  nn      = 101;
  dx      = 2.0 / (PetscReal)(nn - 1);
  overlap = 0;
  PetscCall(DMDACreate2d(PETSC_COMM_WORLD, DM_BOUNDARY_NONE, DM_BOUNDARY_NONE, DMDA_STENCIL_BOX, nn, nn, PETSC_DECIDE, PETSC_DECIDE, 1, overlap, NULL, NULL, &dmcell));
  PetscCall(DMSetFromOptions(dmcell));
  PetscCall(DMSetUp(dmcell));
  PetscCall(DMDASetUniformCoordinates(dmcell, -1.0, 1.0, -1.0, 1.0, -1.0, 1.0));
  PetscCall(DMDAGetCorners(dmcell, &is, &js, NULL, &ni, &nj, NULL));
  PetscCall(DMCreate(PETSC_COMM_WORLD, &dms));
  PetscCall(DMSetType(dms, DMSWARM));
  PetscCall(PetscObjectSetName((PetscObject)dms, "Particles"));

  /* load in data types */
  PetscCall(DMSwarmInitializeFieldRegister(dms));
  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "viscosity", 1, PETSC_REAL));
  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "coorx", 1, PETSC_REAL));
  PetscCall(DMSwarmRegisterPetscDatatypeField(dms, "coory", 1, PETSC_REAL));
  PetscCall(DMSwarmFinalizeFieldRegister(dms));
  PetscCall(DMSwarmSetLocalSizes(dms, ni * nj * 4, 4));
  PetscCall(DMView(dms, PETSC_VIEWER_STDOUT_WORLD));

  /* set values within the swarm */
  {
    PetscReal   *array_x, *array_y;
    PetscInt     npoints, i, j, cnt;
    DMDACoor2d **LA_coor;
    Vec          coor;
    DM           dmcellcdm;

    PetscCall(DMGetCoordinateDM(dmcell, &dmcellcdm));
    PetscCall(DMGetCoordinates(dmcell, &coor));
    PetscCall(DMDAVecGetArray(dmcellcdm, coor, &LA_coor));
    PetscCall(DMSwarmGetLocalSize(dms, &npoints));
    PetscCall(DMSwarmGetField(dms, "coorx", NULL, NULL, (void **)&array_x));
    PetscCall(DMSwarmGetField(dms, "coory", NULL, NULL, (void **)&array_y));
    cnt = 0;
    for (j = js; j < js + nj; j++) {
      for (i = is; i < is + ni; i++) {
        PetscReal xp, yp;

        xp                   = PetscRealPart(LA_coor[j][i].x);
        yp                   = PetscRealPart(LA_coor[j][i].y);
        array_x[4 * cnt + 0] = xp - dx * 0.1; /*if (array_x[4*cnt+0] < -1.0) array_x[4*cnt+0] = -1.0+1.0e-12;*/
        array_x[4 * cnt + 1] = xp + dx * 0.1; /*if (array_x[4*cnt+1] > 1.0)  { array_x[4*cnt+1] =  1.0-1.0e-12; }*/
        array_x[4 * cnt + 2] = xp - dx * 0.1; /*if (array_x[4*cnt+2] < -1.0) array_x[4*cnt+2] = -1.0+1.0e-12;*/
        array_x[4 * cnt + 3] = xp + dx * 0.1; /*if (array_x[4*cnt+3] > 1.0)  { array_x[4*cnt+3] =  1.0-1.0e-12; }*/
        array_y[4 * cnt + 0] = yp - dx * 0.1; /*if (array_y[4*cnt+0] < -1.0) array_y[4*cnt+0] = -1.0+1.0e-12;*/
        array_y[4 * cnt + 1] = yp - dx * 0.1; /*if (array_y[4*cnt+1] < -1.0) array_y[4*cnt+1] = -1.0+1.0e-12;*/
        array_y[4 * cnt + 2] = yp + dx * 0.1; /*if (array_y[4*cnt+2] > 1.0)  { array_y[4*cnt+2] =  1.0-1.0e-12; }*/
        array_y[4 * cnt + 3] = yp + dx * 0.1; /*if (array_y[4*cnt+3] > 1.0)  { array_y[4*cnt+3] =  1.0-1.0e-12; }*/
        cnt++;
      }
    }
    PetscCall(DMSwarmRestoreField(dms, "coory", NULL, NULL, (void **)&array_y));
    PetscCall(DMSwarmRestoreField(dms, "coorx", NULL, NULL, (void **)&array_x));
    PetscCall(DMDAVecRestoreArray(dmcellcdm, coor, &LA_coor));
  }
  PetscCall(PetscMalloc1(1, &zone));
  if (size == 4) {
    if (rank == 0) {
      zone->cx[0]  = 0.5;
      zone->cx[1]  = 0.5;
      zone->radius = 0.3;
    }
    if (rank == 1) {
      zone->cx[0]  = -0.5;
      zone->cx[1]  = 0.5;
      zone->radius = 0.25;
    }
    if (rank == 2) {
      zone->cx[0]  = 0.5;
      zone->cx[1]  = -0.5;
      zone->radius = 0.2;
    }
    if (rank == 3) {
      zone->cx[0]  = -0.5;
      zone->cx[1]  = -0.5;
      zone->radius = 0.1;
    }
  } else {
    if (rank == 0) {
      zone->cx[0]  = 0.5;
      zone->cx[1]  = 0.5;
      zone->radius = 0.8;
    } else {
      zone->cx[0]  = 10.0;
      zone->cx[1]  = 10.0;
      zone->radius = 0.0;
    }
  }
  {
    PetscInt npoints[2], npoints_orig[2], ng;

    PetscCall(DMSwarmGetLocalSize(dms, &npoints_orig[0]));
    PetscCall(DMSwarmGetSize(dms, &npoints_orig[1]));
    PetscCall(PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD, "rank[%d] before(%" PetscInt_FMT ",%" PetscInt_FMT ")\n", rank, npoints_orig[0], npoints_orig[1]));
    PetscCall(PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(DMSwarmCollect_General(dms, collect_zone, sizeof(CollectZoneCtx), zone, &ng));
    PetscCall(DMSwarmGetLocalSize(dms, &npoints[0]));
    PetscCall(DMSwarmGetSize(dms, &npoints[1]));
    PetscCall(PetscViewerASCIIPushSynchronized(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_WORLD, "rank[%d] after(%" PetscInt_FMT ",%" PetscInt_FMT ")\n", rank, npoints[0], npoints[1]));
    PetscCall(PetscViewerFlush(PETSC_VIEWER_STDOUT_WORLD));
    PetscCall(PetscViewerASCIIPopSynchronized(PETSC_VIEWER_STDOUT_WORLD));
  }
  {
    PetscReal *array_x, *array_y;
    PetscInt   npoints, p;
    FILE      *fp = NULL;
    char       name[PETSC_MAX_PATH_LEN];

    PetscCall(PetscSNPrintf(name, PETSC_MAX_PATH_LEN - 1, "c-rank%d.gp", rank));
    fp = fopen(name, "w");
    PetscCheck(fp, PETSC_COMM_SELF, PETSC_ERR_FILE_OPEN, "Cannot open file %s", name);
    PetscCall(DMSwarmGetLocalSize(dms, &npoints));
    PetscCall(DMSwarmGetField(dms, "coorx", NULL, NULL, (void **)&array_x));
    PetscCall(DMSwarmGetField(dms, "coory", NULL, NULL, (void **)&array_y));
    for (p = 0; p < npoints; p++) fprintf(fp, "%+1.4e %+1.4e %1.4e\n", array_x[p], array_y[p], (double)rank);
    PetscCall(DMSwarmRestoreField(dms, "coory", NULL, NULL, (void **)&array_y));
    PetscCall(DMSwarmRestoreField(dms, "coorx", NULL, NULL, (void **)&array_x));
    fclose(fp);
  }
  PetscCall(DMDestroy(&dmcell));
  PetscCall(DMDestroy(&dms));
  PetscCall(PetscFree(zone));
  PetscFunctionReturn(PETSC_SUCCESS);
}

int main(int argc, char **argv)
{
  PetscInt test_mode = 4;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, NULL, help));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-test_mode", &test_mode, NULL));
  if (test_mode == 1) {
    PetscCall(ex1_1());
  } else if (test_mode == 2) {
    PetscCall(ex1_2());
  } else if (test_mode == 3) {
    PetscCall(ex1_3());
  } else if (test_mode == 4) {
    PetscCall(ex1_4());
  } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_USER, "Unknown test_mode value, should be 1,2,3,4");
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   build:
      requires: !complex double

   test:
      args: -test_mode 1
      filter: grep -v atomic
      filter_output: grep -v atomic

   test:
      suffix: 2
      args: -test_mode 2
      filter: grep -v atomic
      filter_output: grep -v atomic

   test:
      suffix: 3
      args: -test_mode 3
      filter: grep -v atomic
      filter_output: grep -v atomic
      TODO: broken

   test:
      suffix: 4
      args: -test_mode 4
      filter: grep -v atomic
      filter_output: grep -v atomic

   test:
      suffix: 5
      nsize: 4
      args: -test_mode 1
      filter: grep -v atomic
      filter_output: grep -v atomic

   test:
      suffix: 6
      nsize: 4
      args: -test_mode 2
      filter: grep -v atomic
      filter_output: grep -v atomic

   test:
      suffix: 7
      nsize: 4
      args: -test_mode 3
      filter: grep -v atomic
      filter_output: grep -v atomic
      TODO: broken

   test:
      suffix: 8
      nsize: 4
      args: -test_mode 4
      filter: grep -v atomic
      filter_output: grep -v atomic

TEST*/