Information about the sub-regions generated by RCB can be obtained by an
application through calls to
Zoltan_RCB_Box. This function is not
required to perform load balancing; it only provides auxiliary information
to an application.
|RCB_OVERALLOC||The amount by which to over-allocate temporary storage arrays
within the RCB algorithm when additional storage is due to changes in
1.0 = no extra storage allocated; 1.5 = 50% extra storage; etc.
|RCB_REUSE||Flag to indicate whether to use previous cuts as initial
the current RCB invocation.
0 = don't use previous cuts; 1 = use previous cuts.
|RCB_OUTPUT_LEVEL||Flag controlling the amount of timing and diagnostic output
0 = no output; 1 = print summary; 2 = print data for each processor.
|CHECK_GEOM||Flag controlling the invocation of input and output error
0 = don't do checking; 1 = do checking.
|KEEP_CUTS||Should information about the cuts determining the RCB
be retained? It costs a bit of time to do so, but this information is
if application wants to add more objects to the decomposition via calls
or to Zoltan_LB_Box_PP_Assign.
0 = don't keep cuts; 1 = keep cuts.
|AVERAGE_CUTS||When set to one, coordinates of RCB cutting planes are computed to be the
average of the coordinates of the closest object on each side of the cut.
Otherwise, coordinates of cutting planes may equal those of one of the
0 = don't average cuts; 1 = average cuts.
|RCB_LOCK_DIRECTIONS||Flag that determines whether the order of the directions of
the cuts is kept
constant after they are determined the first time RCB is called.
0 = don't lock directions; 1 = lock directions.
|RCB_SET_DIRECTIONS||If this flag is set, the order of cuts is changed so that all
of the cuts
in any direction are done as a group. The number of cuts in each
determined and then the value of the parameter is used to determine the
that those cuts are made in. When 1D and 2D problems are partitioned,
directions corresponding to unused dimensions are ignored.
0 = don't order cuts; 1 = xyz; 2 = xzy; 3 = yzx; 4 = yxz; 5 = zxy; 6 = zyx;
|RCB_RECTILINEAR_BLOCKS||Flag controlling the shape of the resulting regions. If this
specified, then when a cut is made, all of the dots located on the cut
moved to the same side of the cut. The resulting regions are then
rectilinear. When these dots are treated as a group, then the resulting
load balance may not be as good as when the group of dots is split by
0 = move dots individually; 1 = move dots in groups.
|REDUCE_DIMENSIONS||When a 3 dimensional geometry is almost flat, it may make more sense to treat it as a 2 dimensional geometry when applying the RCB algorithm. In this case, a 2 dimensional RCB calculation is applied to a plane that corresponds with the geometry. (This results in cuts that, while still orthogonal, may no longer be axis aligned.) If this parameter is set to 1, a 3 dimensional geometry will be treated as 2 dimensional if it is very flat, or 1 dimensional if it is very thin. A 2 dimensional geometry will be treated as 1 dimensional if it is very thin.|
|DEGENERATE_RATIO||If the REDUCE_DIMENSIONS parameter is set, then this parameter determines when a geometry is considered to be degenerate. A bounding box which is oriented to the geometry is constructed, and the lengths of its sides are tested against a ratio of 1 : DEGENERATE_RATIO.||RCB_RECOMPUTE_BOX||Flag indicating whether the bounding box of set of parts is
recomputed at each level of recursion. By default, the longest direction
of the bounding box is cut during bisection. Recomputing the bounding
box at each level of recursion can produce more effective cut directions
for unusually shaped geometries; the computation does, however, take
additional time and communication, and may cause cut directions to
vary from one invocation of RCB to the next.
0 = don't recompute the bounding box; 1 = recompute the box.
||In the multiconstraint case, are
the object weights comparable? Do they have the same units and is the
scaling meaningful? For example, if the jth weight corresponds to the
expected time in phase j (measured in seconds), set this parameter to
1. (0 = incomparable, 1 = comparable)
||Norm used in multicriteria
algorithm; this determines how to balance the different weight
constraints. Valid values are 1,2, and 3. Roughly, if the weights
correspond to different phases, then the value 1 (1-norm) tries to
minimize the total time (sum over all phases) while the value 3
(max-norm) attempts to minimize the worst imbalance in any phase. The
2-norm does something in between. Try a different value if you're
not happy with the balance.
||Maximum allowed ratio between
the largest and smallest side of a subdomain. Must be > 1.
|RCB_OVERALLOC = 1.2|
|RCB_REUSE = 0|
|RCB_OUTPUT_LEVEL = 0|
|CHECK_GEOM = 1|
|KEEP_CUTS = 0|
|AVERAGE_CUTS = 0|
|RCB_LOCK_DIRECTIONS = 0|
|REDUCE_DIMENSIONS = 0|
|DEGENERATE_RATIO = 10|
|RCB_SET_DIRECTIONS = 0|
|RCB_RECTILINEAR_BLOCKS = 0|
|RCB_RECOMPUTE_BOX = 0|
|OBJ_WEIGHTS_COMPARABLE = 0
|RCB_MULTICRITERIA_NORM = 1
|RCB_MAX_ASPECT_RATIO = 10
|Required Query Functions:|
|ZOLTAN_GEOM_MULTI_FN or ZOLTAN_GEOM_FN|
int Zoltan_RCB_Box (
struct Zoltan_Struct * zz,
|FORTRAN:|| FUNCTION Zoltan_RCB_Box(zz, part,ndim, xmin, ymin, zmin,
xmax, ymax, zmax)
INTEGER(Zoltan_INT) :: Zoltan_RCB_Box
TYPE(Zoltan_Struct), INTENT(IN) :: zz
INTEGER(Zoltan_INT), INTENT(IN) :: part
INTEGER(Zoltan_INT), INTENT(OUT) :: ndim
REAL(Zoltan_DOUBLE), INTENT(OUT) :: xmin, ymin, zmin, xmax, ymax, zmax
|zz||Pointer to the Zoltan structure created by Zoltan_Create.|
|part||Part number of part for which the bounding box should be returned.|
|ndim||Upon return, the number of dimensions in the partitioned geometry.|
|xmin, ymin, zmin||Upon return, the coordinates of the lower extent of bounding box for the part. If the geometry is two-dimensional, zmin is -DBL_MAX. If the geometry is one-dimensional, ymin is -DBL_MAX.|
|xmax, ymax, zmax||Upon return, the coordinates of the upper extent of bounding box for the part. If the geometry is two-dimensional, zmax is DBL_MAX. If the geometry is one-dimensional, ymax is DBL_MAX.|