/* * 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, srealloc, sfree #include "structs.h" // for vtx_data #include // for NULL, printf void makecgraph2(struct vtx_data **graph, /* array of vtx data for graph */ int nvtxs, /* number of vertices in graph */ int nedges, /* number of edges 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; /* 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 *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 *ewptr = NULL; /* loops through eweights */ float *fptr = NULL; /* loops through eweights */ float ewgt; /* 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 *eptr = NULL; /* loops through edges data structure */ int cvtx; /* vertex number in coarsened graph */ int cneighbor; /* neighboring vertex number in coarsened graph */ double m1, m2; /* vertex weights of vertices being merged */ int v1, v2; /* vertices being merged */ 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); /* Compute an upper bound on the number of coarse graph edges. */ cnedges = nedges - nmerged; /* 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) { ewptr = eweights = smalloc(size * sizeof(float)); } /* Zero all the seen flags. */ seenflag = smalloc((cnvtxs + 1) * sizeof(int)); sptr = seenflag; for (i = cnvtxs; i; i--) { *(++sptr) = 0; } /* Use the renumbering to fill in the edge lists for the new graph. */ /* Note: This assumes coarse graph vertices are encountered in order. */ cnedges = 0; eptr = edges; ewgt = 1; sptr = seenflag; 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] = links++; if (COARSEN_VWGTS) { cgptr->vwgt = 0; } else { cgptr->vwgt = 1; } eptr[0] = cvtx; cgptr->edges = eptr; if (COARSEN_EWGTS) { cgptr->ewgts = ewptr; } else { cgptr->ewgts = NULL; } *(++sptr) = 0; 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; } /* Increment pointers into edges list. */ cgptr->nedges = nseen; eptr += nseen; if (COARSEN_EWGTS) { ewptr += nseen; } /* Now clear the seenflag values. */ iptr = cgptr->edges; for (j = nseen - 1; j; j--) { seenflag[*(++iptr)] = 0; } cnedges += nseen - 1; } } sfree(seenflag); /* 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; } } /* If desired, make new vtx coordinates = center-of-mass of their parents. */ if (coords != NULL && ccoords != NULL && igeom > 0) { for (i = 0; i < igeom; i++) { ccoords[i] = smalloc((cnvtxs + 1) * sizeof(float)); } for (j = 1; j <= nvtxs; j++) { if (mflag[j] == 0) { /* If unmatched, leave it alone. */ for (i = 0; i < igeom; i++) { ccoords[i][v2cv[j]] = coords[i][j]; } } else if (j < mflag[j]) { /* If matched, use center of mass. */ v1 = j; v2 = mflag[j]; m1 = graph[v1]->vwgt; m2 = graph[v2]->vwgt; for (i = 0; i < igeom; i++) { ccoords[i][v2cv[j]] = (m1 * coords[i][v1] + m2 * coords[i][v2]) / (m1 + m2); } } } } cnedges /= 2; *pcnedges = cnedges; size = 2 * cnedges + cnvtxs; edges = srealloc(edges, size * sizeof(int)); if (COARSEN_EWGTS) { eweights = srealloc(eweights, size * sizeof(float)); } if (DEBUG_COARSEN > 0) { printf(" Coarse graph has %d vertices and %d edges\n", cnvtxs, cnedges); } make_cgraph_time += seconds() - time; sfree(links); sfree(eweights); sfree(edges); }