// Partition Interface
int Zoltan_LB_Partition (
      struct Zoltan_Struct *zz,
      int *changes,
      int *num_gid_entries,
      int *num_lid_entries,
      int *num_import, 
      ZOLTAN_ID_PTR *import_global_ids,
      ZOLTAN_ID_PTR *import_local_ids,
      int **import_procs,
      int **import_to_part,
      int *num_export,
      ZOLTAN_ID_PTR *export_global_ids,
      ZOLTAN_ID_PTR *export_local_ids,
      int **export_procs,
      int **export_to_part);

#include "zoltan.h"
/* Application data type for particle simulation. */
struct Particle {
  int id;
  double x, y, z;
  /* ... solution values, etc. ... */
};

/* Return coordinates for objects requested by Zoltan in globalIDs array. */
void user_geom_multi_fn(void *data, int nge, int nle, int numObj,
  ZOLTAN_ID_PTR globalIDs, ZOLTAN_ID_PTR localIDs,
  int dim, double *geomVec, int *err)
{
  /* Cast data pointer provided in Zoltan_Set_Fn to application data type. */
  /* Application data is an array of Particle structures. */
  struct Particle *user_particles = (struct Particle *) data;
  /* Assume for this example that each globalID and localID is one integer. */
  /* Each globalID is a global particle number; each localID is an index */
  /* into the user’s array of Particles. */
  if (nge != 1 || nle != 1) {*err = ZOLTAN_FATAL; return;}
  /* Loop over objects for which coordinates are requested */
  int i, j = 0;
  for (i = 0; i < numObj; i++) {
    /* Copy the coordinates for the object globalID[i] (with localID[i]) */
    /* into the geomVec vector. Note that Zoltan allocates geomVec. */
    geomVec[j++] = user_particles[localIDs[i]].x;
    if (dim > 1) geomVec[j++] = user_particles[localIDs[i]].y;
    if (dim > 2) geomVec[j++] = user_particles[localIDs[i]].z;
  }
  *err = ZOLTAN_OK;
}