gidx_distance_leaf_centroid()

static double gidx_distance_leaf_centroid ( const GIDX *  a, const GIDX *  b  )

static

Calculate the centroid->centroid distance between the boxes.

Definition at line 468 of file gserialized_gist_nd.c.

Referenced by gserialized_distance_nd(), and gserialized_gist_distance().

{
  int ndims, i;
  double sum = 0;

  /* Base computation on least available dimensions */
  ndims = Min(GIDX_NDIMS(b), GIDX_NDIMS(a));
  for ( i = 0; i < ndims; ++i )
  {
    double ca, cb, d;
    double amin = GIDX_GET_MIN(a,i);
    double amax = GIDX_GET_MAX(a,i);
    double bmin = GIDX_GET_MIN(b,i);
    double bmax = GIDX_GET_MAX(b,i);
    ca = amin + ( ( amax - amin ) / 2.0 );
    cb = bmin + ( ( bmax - bmin ) / 2.0 );
    d = ca - cb;
    if ( ! isfinite(d) )
    {
      /* Can happen if a dimension was padded with FLT_MAX,
       * effectively meaning "infinite range". In that case
       * we take that dimension as adding 0 to the total
       * distance.
       */
      continue;
    }
    sum += d * d;
/*
    POSTGIS_DEBUGF(3, " centroid of A for dimension %d is %g", i, ca);
    POSTGIS_DEBUGF(3, " centroid of B for dimension %d is %g", i, cb);
    POSTGIS_DEBUGF(3, " distance on dimension %d is %g, squared as %g, grows sum to %g", i, d, d*d, sum);
*/
  }
  return sqrt(sum);
}

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