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253 lines
8.8 KiB
253 lines
8.8 KiB
/*
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* Copyright(C) 1999-2020, 2022, 2023 National Technology & Engineering Solutions
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* of Sandia, LLC (NTESS). Under the terms of Contract DE-NA0003525 with
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* NTESS, the U.S. Government retains certain rights in this software.
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*
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* See packages/seacas/LICENSE for details
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*/
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#include "smalloc.h" // for smalloc, srealloc, sfree
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#include "structs.h" // for vtx_data
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#include <stdio.h> // for NULL, printf
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void makecgraph2(struct vtx_data **graph, /* array of vtx data for graph */
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int nvtxs, /* number of vertices in graph */
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int nedges, /* number of edges in graph */
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struct vtx_data ***pcgraph, /* coarsened version of graph */
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int *pcnvtxs, /* number of vtxs in coarsened graph */
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int *pcnedges, /* number of edges in coarsened graph */
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int *mflag, /* flag indicating vtx matched or not */
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int *v2cv, /* mapping from vtxs to coarsened vtxs */
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int nmerged, /* number of merged vertices */
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int using_ewgts, /* are edge weights being used? */
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int igeom, /* dimensions of geometric data */
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float **coords, /* coordinates for vertices */
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float **ccoords /* coordinates for coarsened vertices */
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)
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{
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extern double make_cgraph_time;
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extern int DEBUG_COARSEN; /* debug flag for coarsening output */
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extern int COARSEN_VWGTS; /* turn off vertex weights in coarse graph? */
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extern int COARSEN_EWGTS; /* turn off edge weights in coarse graph? */
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struct vtx_data **cgraph; /* coarsened version of graph */
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struct vtx_data *links = NULL; /* space for all the vertex data */
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struct vtx_data **gptr = NULL; /* loops through cgraph */
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struct vtx_data *cgptr = NULL; /* loops through cgraph */
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int *iptr = NULL; /* loops through integer arrays */
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int *seenflag = NULL; /* flags for vtxs already put in edge list */
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int *sptr = NULL; /* loops through seenflags */
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float *eweights = NULL; /* space for edge weights in coarsened graph */
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float *ewptr = NULL; /* loops through eweights */
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float *fptr = NULL; /* loops through eweights */
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float ewgt; /* edge weight */
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double ewgt_sum; /* sum of edge weights */
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double time; /* timing parameters */
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int nseen; /* number of edges of coarse graph seen so far */
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int cnvtxs; /* number of vtxs in coarsened graph */
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int cnedges; /* twice number of edges in coarsened graph */
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int neighbor; /* neighboring vertex */
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int size; /* space needed for coarsened graph */
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int *edges = NULL; /* space for edges in coarsened graph */
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int *eptr = NULL; /* loops through edges data structure */
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int cvtx; /* vertex number in coarsened graph */
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int cneighbor; /* neighboring vertex number in coarsened graph */
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double m1, m2; /* vertex weights of vertices being merged */
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int v1, v2; /* vertices being merged */
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int i, j; /* loop counters */
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/* Compute the number of vertices and edges in the coarsened graph, */
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/* and construct start pointers into coarsened edge array. */
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time = seconds();
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*pcnvtxs = cnvtxs = nvtxs - nmerged;
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/* Construct mapping from original graph vtxs to coarsened graph vtxs. */
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makev2cv(mflag, nvtxs, v2cv);
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/* Compute an upper bound on the number of coarse graph edges. */
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cnedges = nedges - nmerged;
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/* Now allocate space for the new graph. */
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*pcgraph = cgraph = smalloc((cnvtxs + 1) * sizeof(struct vtx_data *));
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links = smalloc(cnvtxs * sizeof(struct vtx_data));
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size = 2 * cnedges + cnvtxs;
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edges = smalloc(size * sizeof(int));
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if (COARSEN_EWGTS) {
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ewptr = eweights = smalloc(size * sizeof(float));
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}
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/* Zero all the seen flags. */
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seenflag = smalloc((cnvtxs + 1) * sizeof(int));
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sptr = seenflag;
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for (i = cnvtxs; i; i--) {
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*(++sptr) = 0;
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}
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/* Use the renumbering to fill in the edge lists for the new graph. */
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/* Note: This assumes coarse graph vertices are encountered in order. */
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cnedges = 0;
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eptr = edges;
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ewgt = 1;
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sptr = seenflag;
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for (i = 1; i <= nvtxs; i++) {
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if (mflag[i] > i || mflag[i] == 0) {
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/* Unmatched edge, or first appearance of matched edge. */
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nseen = 1;
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cvtx = v2cv[i];
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cgptr = cgraph[cvtx] = links++;
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if (COARSEN_VWGTS) {
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cgptr->vwgt = 0;
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}
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else {
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cgptr->vwgt = 1;
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}
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eptr[0] = cvtx;
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cgptr->edges = eptr;
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if (COARSEN_EWGTS) {
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cgptr->ewgts = ewptr;
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}
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else {
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cgptr->ewgts = NULL;
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}
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*(++sptr) = 0;
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ewgt_sum = 0;
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iptr = graph[i]->edges;
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if (using_ewgts) {
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fptr = graph[i]->ewgts;
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}
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for (j = graph[i]->nedges - 1; j; j--) {
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neighbor = *(++iptr);
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cneighbor = v2cv[neighbor];
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if (cneighbor != cvtx) {
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if (using_ewgts) {
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ewgt = *(++fptr);
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}
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ewgt_sum += ewgt;
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/* Seenflags being used as map from cvtx to index. */
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if (seenflag[cneighbor] == 0) { /* New neighbor. */
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cgptr->edges[nseen] = cneighbor;
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if (COARSEN_EWGTS) {
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cgptr->ewgts[nseen] = ewgt;
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}
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seenflag[cneighbor] = nseen++;
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}
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else { /* Already seen neighbor. */
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if (COARSEN_EWGTS) {
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cgptr->ewgts[seenflag[cneighbor]] += ewgt;
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}
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}
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}
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else if (using_ewgts) {
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++fptr;
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}
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}
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if (mflag[i] > i) { /* Now handle the matched vertex. */
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iptr = graph[mflag[i]]->edges;
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if (using_ewgts) {
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fptr = graph[mflag[i]]->ewgts;
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}
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for (j = graph[mflag[i]]->nedges - 1; j; j--) {
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neighbor = *(++iptr);
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cneighbor = v2cv[neighbor];
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if (cneighbor != cvtx) {
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if (using_ewgts) {
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ewgt = *(++fptr);
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}
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ewgt_sum += ewgt;
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if (seenflag[cneighbor] == 0) { /* New neighbor. */
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cgptr->edges[nseen] = cneighbor;
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if (COARSEN_EWGTS) {
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cgptr->ewgts[nseen] = ewgt;
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}
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seenflag[cneighbor] = nseen++;
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}
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else { /* Already seen neighbor. */
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if (COARSEN_EWGTS) {
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cgptr->ewgts[seenflag[cneighbor]] += ewgt;
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}
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}
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}
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else if (using_ewgts) {
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++fptr;
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}
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}
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}
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if (COARSEN_EWGTS) {
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cgptr->ewgts[0] = -ewgt_sum;
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}
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/* Increment pointers into edges list. */
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cgptr->nedges = nseen;
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eptr += nseen;
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if (COARSEN_EWGTS) {
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ewptr += nseen;
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}
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/* Now clear the seenflag values. */
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iptr = cgptr->edges;
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for (j = nseen - 1; j; j--) {
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seenflag[*(++iptr)] = 0;
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}
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cnedges += nseen - 1;
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}
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}
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sfree(seenflag);
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/* Form new vertex weights by adding those from contracted edges. */
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if (COARSEN_VWGTS) {
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gptr = graph;
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for (i = 1; i <= nvtxs; i++) {
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cgraph[v2cv[i]]->vwgt += (*(++gptr))->vwgt;
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}
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}
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/* If desired, make new vtx coordinates = center-of-mass of their parents. */
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if (coords != NULL && ccoords != NULL && igeom > 0) {
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for (i = 0; i < igeom; i++) {
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ccoords[i] = smalloc((cnvtxs + 1) * sizeof(float));
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}
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for (j = 1; j <= nvtxs; j++) {
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if (mflag[j] == 0) { /* If unmatched, leave it alone. */
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for (i = 0; i < igeom; i++) {
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ccoords[i][v2cv[j]] = coords[i][j];
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}
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}
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else if (j < mflag[j]) { /* If matched, use center of mass. */
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v1 = j;
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v2 = mflag[j];
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m1 = graph[v1]->vwgt;
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m2 = graph[v2]->vwgt;
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for (i = 0; i < igeom; i++) {
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ccoords[i][v2cv[j]] = (m1 * coords[i][v1] + m2 * coords[i][v2]) / (m1 + m2);
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}
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}
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}
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}
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cnedges /= 2;
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*pcnedges = cnedges;
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size = 2 * cnedges + cnvtxs;
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edges = srealloc(edges, size * sizeof(int));
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if (COARSEN_EWGTS) {
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eweights = srealloc(eweights, size * sizeof(float));
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}
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if (DEBUG_COARSEN > 0) {
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printf(" Coarse graph has %d vertices and %d edges\n", cnvtxs, cnedges);
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}
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make_cgraph_time += seconds() - time;
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sfree(links);
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sfree(eweights);
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sfree(edges);
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}
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