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/*
\file
\brief This file contains the driving routines for multilevel refinement
\date Started 7/24/1997
\author George
\author Copyright 1997-2009, Regents of the University of Minnesota
\version\verbatim $Id: refine.c 10513 2011-07-07 22:06:03Z karypis $ \endverbatim
*/
#include "metislib.h"
/*************************************************************************/
/*! This function is the entry point of refinement */
/*************************************************************************/
void Refine2Way(ctrl_t *ctrl, graph_t *orggraph, graph_t *graph, real_t *tpwgts)
{
IFSET(ctrl->dbglvl, METIS_DBG_TIME, gk_startcputimer(ctrl->UncoarsenTmr));
/* Compute the parameters of the coarsest graph */
Compute2WayPartitionParams(ctrl, graph);
for (;;) {
ASSERT(CheckBnd(graph));
IFSET(ctrl->dbglvl, METIS_DBG_TIME, gk_startcputimer(ctrl->RefTmr));
Balance2Way(ctrl, graph, tpwgts);
FM_2WayRefine(ctrl, graph, tpwgts, ctrl->niter);
IFSET(ctrl->dbglvl, METIS_DBG_TIME, gk_stopcputimer(ctrl->RefTmr));
if (graph == orggraph)
break;
graph = graph->finer;
IFSET(ctrl->dbglvl, METIS_DBG_TIME, gk_startcputimer(ctrl->ProjectTmr));
Project2WayPartition(ctrl, graph);
IFSET(ctrl->dbglvl, METIS_DBG_TIME, gk_stopcputimer(ctrl->ProjectTmr));
}
IFSET(ctrl->dbglvl, METIS_DBG_TIME, gk_stopcputimer(ctrl->UncoarsenTmr));
}
/*************************************************************************/
/*! This function allocates memory for 2-way edge refinement */
/*************************************************************************/
void Allocate2WayPartitionMemory(ctrl_t *ctrl, graph_t *graph)
{
idx_t nvtxs, ncon;
nvtxs = graph->nvtxs;
ncon = graph->ncon;
graph->pwgts = imalloc(2*ncon, "Allocate2WayPartitionMemory: pwgts");
graph->where = imalloc(nvtxs, "Allocate2WayPartitionMemory: where");
graph->bndptr = imalloc(nvtxs, "Allocate2WayPartitionMemory: bndptr");
graph->bndind = imalloc(nvtxs, "Allocate2WayPartitionMemory: bndind");
graph->id = imalloc(nvtxs, "Allocate2WayPartitionMemory: id");
graph->ed = imalloc(nvtxs, "Allocate2WayPartitionMemory: ed");
}
/*************************************************************************/
/*! This function computes the initial id/ed */
/*************************************************************************/
void Compute2WayPartitionParams(ctrl_t *ctrl, graph_t *graph)
{
idx_t i, j, nvtxs, ncon, nbnd, mincut, istart, iend, tid, ted, me;
idx_t *xadj, *vwgt, *adjncy, *adjwgt, *pwgts;
idx_t *where, *bndptr, *bndind, *id, *ed;
nvtxs = graph->nvtxs;
ncon = graph->ncon;
xadj = graph->xadj;
vwgt = graph->vwgt;
adjncy = graph->adjncy;
adjwgt = graph->adjwgt;
where = graph->where;
id = graph->id;
ed = graph->ed;
pwgts = iset(2*ncon, 0, graph->pwgts);
bndptr = iset(nvtxs, -1, graph->bndptr);
bndind = graph->bndind;
/* Compute pwgts */
if (ncon == 1) {
for (i=0; i<nvtxs; i++) {
ASSERT(where[i] >= 0 && where[i] <= 1);
pwgts[where[i]] += vwgt[i];
}
ASSERT(pwgts[0]+pwgts[1] == graph->tvwgt[0]);
}
else {
for (i=0; i<nvtxs; i++) {
me = where[i];
for (j=0; j<ncon; j++)
pwgts[me*ncon+j] += vwgt[i*ncon+j];
}
}
/* Compute the required info for refinement */
for (nbnd=0, mincut=0, i=0; i<nvtxs; i++) {
istart = xadj[i];
iend = xadj[i+1];
me = where[i];
tid = ted = 0;
for (j=istart; j<iend; j++) {
if (me == where[adjncy[j]])
tid += adjwgt[j];
else
ted += adjwgt[j];
}
id[i] = tid;
ed[i] = ted;
if (ted > 0 || istart == iend) {
BNDInsert(nbnd, bndind, bndptr, i);
mincut += ted;
}
}
graph->mincut = mincut/2;
graph->nbnd = nbnd;
}
/*************************************************************************/
/*! Projects a partition and computes the refinement params. */
/*************************************************************************/
void Project2WayPartition(ctrl_t *ctrl, graph_t *graph)
{
idx_t i, j, istart, iend, nvtxs, nbnd, me, tid, ted;
idx_t *xadj, *adjncy, *adjwgt;
idx_t *cmap, *where, *bndptr, *bndind;
idx_t *cwhere, *cbndptr;
idx_t *id, *ed;
graph_t *cgraph;
Allocate2WayPartitionMemory(ctrl, graph);
cgraph = graph->coarser;
cwhere = cgraph->where;
cbndptr = cgraph->bndptr;
nvtxs = graph->nvtxs;
cmap = graph->cmap;
xadj = graph->xadj;
adjncy = graph->adjncy;
adjwgt = graph->adjwgt;
where = graph->where;
id = graph->id;
ed = graph->ed;
bndptr = iset(nvtxs, -1, graph->bndptr);
bndind = graph->bndind;
/* Project the partition and record which of these nodes came from the
coarser boundary */
for (i=0; i<nvtxs; i++) {
j = cmap[i];
where[i] = cwhere[j];
cmap[i] = cbndptr[j];
}
/* Compute the refinement information of the nodes */
for (nbnd=0, i=0; i<nvtxs; i++) {
istart = xadj[i];
iend = xadj[i+1];
tid = ted = 0;
if (cmap[i] == -1) { /* Interior node. Note that cmap[i] = cbndptr[cmap[i]] */
for (j=istart; j<iend; j++)
tid += adjwgt[j];
}
else { /* Potentially an interface node */
me = where[i];
for (j=istart; j<iend; j++) {
if (me == where[adjncy[j]])
tid += adjwgt[j];
else
ted += adjwgt[j];
}
}
id[i] = tid;
ed[i] = ted;
if (ted > 0 || istart == iend)
BNDInsert(nbnd, bndind, bndptr, i);
}
graph->mincut = cgraph->mincut;
graph->nbnd = nbnd;
/* copy pwgts */
icopy(2*graph->ncon, cgraph->pwgts, graph->pwgts);
FreeGraph(&graph->coarser);
graph->coarser = NULL;
}
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