/*************************************************************************
* This function is the entry point for ONWMETIS. It requires weights on the
* vertices. It is for the case that the matrix has been pre-compressed.
**************************************************************************/
void METIS_EdgeComputeSeparator(int *nvtxs, idxtype *xadj, idxtype *adjncy, idxtype *vwgt,
idxtype *adjwgt, int *options, int *sepsize, idxtype *part)
{
int i, j, tvwgt, tpwgts[2];
GraphType graph;
CtrlType ctrl;
SetUpGraph(&graph, OP_ONMETIS, *nvtxs, 1, xadj, adjncy, vwgt, adjwgt, 3);
tvwgt = idxsum(*nvtxs, graph.vwgt);
if (options[0] == 0) { /* Use the default parameters */
ctrl.CType = ONMETIS_CTYPE;
ctrl.IType = ONMETIS_ITYPE;
ctrl.RType = ONMETIS_RTYPE;
ctrl.dbglvl = ONMETIS_DBGLVL;
}
else {
ctrl.CType = options[OPTION_CTYPE];
ctrl.IType = options[OPTION_ITYPE];
ctrl.RType = options[OPTION_RTYPE];
ctrl.dbglvl = options[OPTION_DBGLVL];
}
ctrl.oflags = 0;
ctrl.pfactor = 0;
ctrl.nseps = 1;
ctrl.optype = OP_OEMETIS;
ctrl.CoarsenTo = amin(100, *nvtxs-1);
ctrl.maxvwgt = (int) 1.5*tvwgt/ctrl.CoarsenTo;
InitRandom(options[7]);
AllocateWorkSpace(&ctrl, &graph, 2);
/*============================================================
* Perform the bisection
*============================================================*/
tpwgts[0] = tvwgt/2;
tpwgts[1] = tvwgt-tpwgts[0];
MlevelEdgeBisection(&ctrl, &graph, tpwgts, 1.05);
ConstructMinCoverSeparator(&ctrl, &graph, 1.05);
*sepsize = graph.pwgts[2];
idxcopy(*nvtxs, graph.where, part);
GKfree((void**) &graph.gdata, (void**) &graph.rdata, (void**) &graph.label, LTERM);
FreeWorkSpace(&ctrl, &graph);
}
/*************************************************************************
* This function takes a graph and produces a bisection of it
**************************************************************************/
idxtype MlevelRecursiveBisection(CtrlType *ctrl, GraphType *graph,
idxtype nparts, idxtype *part, float *tpwgts, float ubfactor,
idxtype fpart)
{
idxtype i, j, nvtxs, cut, tvwgt, tpwgts2[2];
idxtype *label, *where;
GraphType lgraph, rgraph;
float wsum;
nvtxs = graph->nvtxs;
if (nvtxs == 0) {
mprintf("\t***Cannot bisect a graph with 0 vertices!\n\t***You are trying to partition a graph into too many parts!\n");
return 0;
}
/* Determine the weights of the partitions */
tvwgt = idxsum(nvtxs, graph->vwgt, 1);
tpwgts2[0] = tvwgt*gk_fsum(nparts/2, tpwgts, 1);
tpwgts2[1] = tvwgt-tpwgts2[0];
MlevelEdgeBisection(ctrl, graph, tpwgts2, ubfactor);
cut = graph->mincut;
/* mprintf("%5D %5D %5D [%5D %f]\n", tpwgts2[0], tpwgts2[1], cut, tvwgt, gk_fsum(nparts/2, tpwgts, 1));*/
label = graph->label;
where = graph->where;
for (i=0; i<nvtxs; i++)
part[label[i]] = where[i] + fpart;
if (nparts > 2) {
SplitGraphPart(ctrl, graph, &lgraph, &rgraph);
/* mprintf("%D %D\n", lgraph.nvtxs, rgraph.nvtxs); */
}
/* Free the memory of the top level graph */
FreeGraph(graph, 0);
/* Scale the fractions in the tpwgts according to the true weight */
wsum = gk_fsum(nparts/2, tpwgts, 1);
gk_fscale(nparts/2, 1.0/wsum, tpwgts, 1);
gk_fscale(nparts-nparts/2, 1.0/(1.0-wsum), tpwgts+nparts/2, 1);
/*
for (i=0; i<nparts; i++)
mprintf("%5.3f ", tpwgts[i]);
mprintf("[%5.3f]\n", wsum);
*/
/* Do the recursive call */
if (nparts > 3) {
cut += MlevelRecursiveBisection(ctrl, &lgraph, nparts/2, part, tpwgts, ubfactor, fpart);
cut += MlevelRecursiveBisection(ctrl, &rgraph, nparts-nparts/2, part, tpwgts+nparts/2, ubfactor, fpart+nparts/2);
}
else if (nparts == 3) {
cut += MlevelRecursiveBisection(ctrl, &rgraph, nparts-nparts/2, part, tpwgts+nparts/2, ubfactor, fpart+nparts/2);
FreeGraph(&lgraph, 0);
}
return cut;
}