/* * Copyright(C) 1999-2020, 2022, 2023 National Technology & Engineering Solutions * of Sandia, LLC (NTESS). Under the terms of Contract DE-NA0003525 with * NTESS, the U.S. Government retains certain rights in this software. * * See packages/seacas/LICENSE for details */ #include "smalloc.h" // for smalloc, sfree #include "structs.h" // for vtx_data #include // for NULL, printf void makecgraph(struct vtx_data **graph, /* array of vtx data for graph */ int nvtxs, /* number of vertices in graph */ struct vtx_data ***pcgraph, /* coarsened version of graph */ int *pcnvtxs, /* number of vtxs in coarsened graph */ int *pcnedges, /* number of edges in coarsened graph */ int *mflag, /* flag indicating vtx matched or not */ int *v2cv, /* mapping from vtxs to coarsened vtxs */ int nmerged, /* number of merged vertices */ int using_ewgts, /* are edge weights being used? */ int igeom, /* dimensions of geometric data */ float **coords, /* coordinates for vertices */ float **ccoords /* coordinates for coarsened vertices */ ) { extern double make_cgraph_time; extern int DEBUG_COARSEN; /* debug flag for coarsening output */ extern int COARSEN_VWGTS; /* turn off vertex weights in coarse graph? */ extern int COARSEN_EWGTS; /* turn off edge weights in coarse graph? */ struct vtx_data **cgraph = NULL; /* coarsened version of graph */ struct vtx_data *links = NULL; /* space for all the vertex data */ struct vtx_data **gptr = NULL; /* loops through cgraph */ struct vtx_data *cgptr = NULL; /* loops through cgraph */ int *start = NULL; /* start of edgevals list for each vertex */ int *iptr = NULL; /* loops through integer arrays */ int *seenflag = NULL; /* flags for vtxs already put in edge list */ int *sptr = NULL; /* loops through seenflags */ float *eweights = NULL; /* space for edge weights in coarsened graph */ float *fptr = NULL; /* loops through eweights */ float ewgt = 0.0; /* edge weight */ double ewgt_sum; /* sum of edge weights */ double time; /* timing parameters */ int nseen; /* number of edges of coarse graph seen so far */ int cnvtxs; /* number of vtxs in coarsened graph */ int cnedges; /* twice number of edges in coarsened graph */ int neighbor; /* neighboring vertex */ int size; /* space needed for coarsened graph */ int *edges = NULL; /* space for edges in coarsened graph */ int cvtx; /* vertex number in coarsened graph */ int cneighbor; /* neighboring vertex number in coarsened graph */ int i, j; /* loop counters */ /* Compute the number of vertices and edges in the coarsened graph, */ /* and construct start pointers into coarsened edge array. */ time = seconds(); *pcnvtxs = cnvtxs = nvtxs - nmerged; /* Construct mapping from original graph vtxs to coarsened graph vtxs. */ makev2cv(mflag, nvtxs, v2cv); start = smalloc((cnvtxs + 2) * sizeof(int)); seenflag = smalloc((cnvtxs + 1) * sizeof(int)); sptr = seenflag; for (i = cnvtxs; i; i--) { *(++sptr) = 0; } countcedges(graph, nvtxs, start, seenflag, mflag, v2cv, pcnedges); cnedges = *pcnedges; if (DEBUG_COARSEN > 0) { printf(" Coarse graph has %d vertices and %d edges\n", cnvtxs, cnedges); } /* Now allocate space for the new graph. */ *pcgraph = cgraph = smalloc((cnvtxs + 1) * sizeof(struct vtx_data *)); links = smalloc(cnvtxs * sizeof(struct vtx_data)); size = 2 * cnedges + cnvtxs; edges = smalloc(size * sizeof(int)); if (COARSEN_EWGTS) { eweights = smalloc(size * sizeof(float)); } /* Fill in simple data fields for coarsened graph. */ /* Edges and weights are put in later. */ gptr = cgraph; sptr = seenflag; for (i = 1; i <= cnvtxs; i++) { size = start[i + 1] - start[i] + 1; links->nedges = size; links->edges = edges; links->edges[0] = i; edges += size; if (COARSEN_VWGTS) { links->vwgt = 0; } else { links->vwgt = 1; } if (COARSEN_EWGTS) { links->ewgts = eweights; eweights += size; } else { links->ewgts = NULL; } *(++gptr) = links++; *(++sptr) = 0; } sfree(start); /* Now form new vertex weights by adding those from contracted edges. */ if (COARSEN_VWGTS) { gptr = graph; for (i = 1; i <= nvtxs; i++) { cgraph[v2cv[i]]->vwgt += (*(++gptr))->vwgt; } } /* Use the renumbering to fill in the edge lists for the new graph. */ ewgt = 1; for (i = 1; i <= nvtxs; i++) { if (mflag[i] > i || mflag[i] == 0) { /* Unmatched edge, or first appearance of matched edge. */ nseen = 1; cvtx = v2cv[i]; cgptr = cgraph[cvtx]; ewgt_sum = 0; iptr = graph[i]->edges; if (using_ewgts) { fptr = graph[i]->ewgts; } for (j = graph[i]->nedges - 1; j; j--) { neighbor = *(++iptr); cneighbor = v2cv[neighbor]; if (cneighbor != cvtx) { if (using_ewgts) { ewgt = *(++fptr); } ewgt_sum += ewgt; /* Seenflags being used as map from cvtx to index. */ if (seenflag[cneighbor] == 0) { /* New neighbor. */ cgptr->edges[nseen] = cneighbor; if (COARSEN_EWGTS) { cgptr->ewgts[nseen] = ewgt; } seenflag[cneighbor] = nseen++; } else { /* Already seen neighbor. */ if (COARSEN_EWGTS) { cgptr->ewgts[seenflag[cneighbor]] += ewgt; } } } else if (using_ewgts) { ++fptr; } } if (mflag[i] > i) { /* Now handle the matched vertex. */ iptr = graph[mflag[i]]->edges; if (using_ewgts) { fptr = graph[mflag[i]]->ewgts; } for (j = graph[mflag[i]]->nedges - 1; j; j--) { neighbor = *(++iptr); cneighbor = v2cv[neighbor]; if (cneighbor != cvtx) { if (using_ewgts) { ewgt = *(++fptr); } ewgt_sum += ewgt; if (seenflag[cneighbor] == 0) { /* New neighbor. */ cgptr->edges[nseen] = cneighbor; if (COARSEN_EWGTS) { cgptr->ewgts[nseen] = ewgt; } seenflag[cneighbor] = nseen++; } else { /* Already seen neighbor. */ if (COARSEN_EWGTS) { cgptr->ewgts[seenflag[cneighbor]] += ewgt; } } } else if (using_ewgts) { ++fptr; } } } if (COARSEN_EWGTS) { cgptr->ewgts[0] = -ewgt_sum; } /* Now clear the seenflag values. */ iptr = cgraph[cvtx]->edges; for (j = cgraph[cvtx]->nedges - 1; j; j--) { seenflag[*(++iptr)] = 0; } } } sfree(seenflag); /* If desired, make new vtx coordinates = center-of-mass of their parents. */ if (coords != NULL && ccoords != NULL && igeom > 0) { makeccoords(graph, cnvtxs, mflag, v2cv, igeom, coords, ccoords); } make_cgraph_time += seconds() - time; }