xref: /petsc/src/ksp/pc/impls/gamg/geo.c (revision c77c71ff2d9eaa2c74538bf9bf94eff01b512dbf)
1 /*
2  GAMG geometric-algebric multiogrid PC - Mark Adams 2011
3  */
4 
5 #include <../src/ksp/pc/impls/gamg/gamg.h> /*I "petscpc.h" I*/
6 
7 #if defined(PETSC_HAVE_TRIANGLE)
8   #if !defined(ANSI_DECLARATORS)
9     #define ANSI_DECLARATORS
10   #endif
11   #include <triangle.h>
12 #endif
13 
14 #include <petscblaslapack.h>
15 
16 /* Private context for the GAMG preconditioner */
17 typedef struct {
18   PetscInt lid;    /* local vertex index */
19   PetscInt degree; /* vertex degree */
20 } GAMGNode;
21 
22 static inline int petsc_geo_mg_compare(const void *a, const void *b)
23 {
24   return (((GAMGNode *)a)->degree - ((GAMGNode *)b)->degree);
25 }
26 
27 /*
28    PCSetCoordinates_GEO
29 
30    Input Parameter:
31    .  pc - the preconditioner context
32 */
33 PetscErrorCode PCSetCoordinates_GEO(PC pc, PetscInt ndm, PetscInt a_nloc, PetscReal *coords)
34 {
35   PC_MG   *mg      = (PC_MG *)pc->data;
36   PC_GAMG *pc_gamg = (PC_GAMG *)mg->innerctx;
37   PetscInt arrsz, bs, my0, kk, ii, nloc, Iend, aloc;
38   Mat      Amat = pc->pmat;
39 
40   PetscFunctionBegin;
41   PetscValidHeaderSpecific(Amat, MAT_CLASSID, 1);
42   PetscCall(MatGetBlockSize(Amat, &bs));
43   PetscCall(MatGetOwnershipRange(Amat, &my0, &Iend));
44   aloc = (Iend - my0);
45   nloc = (Iend - my0) / bs;
46 
47   PetscCheck(nloc == a_nloc || aloc == a_nloc, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Number of local blocks %" PetscInt_FMT " must be %" PetscInt_FMT " or %" PetscInt_FMT ".", a_nloc, nloc, aloc);
48 
49   pc_gamg->data_cell_rows = 1;
50   PetscCheck(coords || (nloc <= 0), PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Need coordinates for pc_gamg_type 'geo'.");
51   pc_gamg->data_cell_cols = ndm; /* coordinates */
52 
53   arrsz = nloc * pc_gamg->data_cell_rows * pc_gamg->data_cell_cols;
54 
55   /* create data - syntactic sugar that should be refactored at some point */
56   if (!pc_gamg->data || (pc_gamg->data_sz != arrsz)) {
57     PetscCall(PetscFree(pc_gamg->data));
58     PetscCall(PetscMalloc1(arrsz + 1, &pc_gamg->data));
59   }
60   for (kk = 0; kk < arrsz; kk++) pc_gamg->data[kk] = -999.;
61   pc_gamg->data[arrsz] = -99.;
62   /* copy data in - column oriented */
63   if (nloc == a_nloc) {
64     for (kk = 0; kk < nloc; kk++) {
65       for (ii = 0; ii < ndm; ii++) pc_gamg->data[ii * nloc + kk] = coords[kk * ndm + ii];
66     }
67   } else { /* assumes the coordinates are blocked */
68     for (kk = 0; kk < nloc; kk++) {
69       for (ii = 0; ii < ndm; ii++) pc_gamg->data[ii * nloc + kk] = coords[bs * kk * ndm + ii];
70     }
71   }
72   PetscCheck(pc_gamg->data[arrsz] == -99., PETSC_COMM_SELF, PETSC_ERR_PLIB, "pc_gamg->data[arrsz %" PetscInt_FMT "] %g != -99.", arrsz, (double)pc_gamg->data[arrsz]);
73   pc_gamg->data_sz = arrsz;
74   PetscFunctionReturn(PETSC_SUCCESS);
75 }
76 
77 /*
78    PCSetData_GEO
79 
80   Input Parameter:
81    . pc -
82 */
83 PetscErrorCode PCSetData_GEO(PC pc, Mat m)
84 {
85   PetscFunctionBegin;
86   SETERRQ(PetscObjectComm((PetscObject)pc), PETSC_ERR_PLIB, "GEO MG needs coordinates");
87 }
88 
89 /*
90    PCSetFromOptions_GEO
91 
92   Input Parameter:
93    . pc -
94 */
95 PetscErrorCode PCSetFromOptions_GEO(PC pc, PetscOptionItems *PetscOptionsObject)
96 {
97   PetscFunctionBegin;
98   PetscOptionsHeadBegin(PetscOptionsObject, "GAMG-GEO options");
99   {
100     /* -pc_gamg_sa_nsmooths */
101     /* pc_gamg_sa->smooths = 0; */
102     /* ierr = PetscOptionsInt("-pc_gamg_agg_nsmooths", */
103     /*                        "smoothing steps for smoothed aggregation, usually 1 (0)", */
104     /*                        "PCGAMGSetNSmooths_AGG", */
105     /*                        pc_gamg_sa->smooths, */
106     /*                        &pc_gamg_sa->smooths, */
107     /*                        &flag);  */
108   }
109   PetscOptionsHeadEnd();
110   PetscFunctionReturn(PETSC_SUCCESS);
111 }
112 
113 /*
114  triangulateAndFormProl
115 
116    Input Parameter:
117    . selected_2 - list of selected local ID, includes selected ghosts
118    . data_stride -
119    . coords[2*data_stride] - column vector of local coordinates w/ ghosts
120    . nselected_1 - selected IDs that go with base (1) graph includes selected ghosts
121    . clid_lid_1[nselected_1] - lids of selected (c) nodes   ???????????
122    . agg_lists_1 - list of aggregates selected_1 vertices of aggregate unselected vertices
123    . crsGID[selected.size()] - global index for prolongation operator
124    . bs - block size
125   Output Parameter:
126    . a_Prol - prolongation operator
127    . a_worst_best - measure of worst missed fine vertex, 0 is no misses
128 */
129 static PetscErrorCode triangulateAndFormProl(IS selected_2, PetscInt data_stride, PetscReal coords[], PetscInt nselected_1, const PetscInt clid_lid_1[], const PetscCoarsenData *agg_lists_1, const PetscInt crsGID[], PetscInt bs, Mat a_Prol, PetscReal *a_worst_best)
130 {
131 #if defined(PETSC_HAVE_TRIANGLE)
132   PetscInt             jj, tid, tt, idx, nselected_2;
133   struct triangulateio in, mid;
134   const PetscInt      *selected_idx_2;
135   PetscMPIInt          rank;
136   PetscInt             Istart, Iend, nFineLoc, myFine0;
137   int                  kk, nPlotPts, sid;
138   MPI_Comm             comm;
139   PetscReal            tm;
140 
141   PetscFunctionBegin;
142   PetscCall(PetscObjectGetComm((PetscObject)a_Prol, &comm));
143   PetscCallMPI(MPI_Comm_rank(comm, &rank));
144   PetscCall(ISGetSize(selected_2, &nselected_2));
145   if (nselected_2 == 1 || nselected_2 == 2) { /* 0 happens on idle processors */
146     *a_worst_best = 100.0;                    /* this will cause a stop, but not globalized (should not happen) */
147   } else *a_worst_best = 0.0;
148   PetscCall(MPIU_Allreduce(a_worst_best, &tm, 1, MPIU_REAL, MPIU_MAX, comm));
149   if (tm > 0.0) {
150     *a_worst_best = 100.0;
151     PetscFunctionReturn(PETSC_SUCCESS);
152   }
153   PetscCall(MatGetOwnershipRange(a_Prol, &Istart, &Iend));
154   nFineLoc = (Iend - Istart) / bs;
155   myFine0  = Istart / bs;
156   nPlotPts = nFineLoc; /* locals */
157   /* triangle */
158   /* Define input points - in*/
159   in.numberofpoints          = nselected_2;
160   in.numberofpointattributes = 0;
161   /* get nselected points */
162   PetscCall(PetscMalloc1(2 * nselected_2, &in.pointlist));
163   PetscCall(ISGetIndices(selected_2, &selected_idx_2));
164 
165   for (kk = 0, sid = 0; kk < nselected_2; kk++, sid += 2) {
166     PetscInt lid          = selected_idx_2[kk];
167     in.pointlist[sid]     = coords[lid];
168     in.pointlist[sid + 1] = coords[data_stride + lid];
169     if (lid >= nFineLoc) nPlotPts++;
170   }
171   PetscCheck(sid == 2 * nselected_2, PETSC_COMM_SELF, PETSC_ERR_PLIB, "sid %d != 2*nselected_2 %" PetscInt_FMT, sid, nselected_2);
172 
173   in.numberofsegments      = 0;
174   in.numberofedges         = 0;
175   in.numberofholes         = 0;
176   in.numberofregions       = 0;
177   in.trianglelist          = NULL;
178   in.segmentmarkerlist     = NULL;
179   in.pointattributelist    = NULL;
180   in.pointmarkerlist       = NULL;
181   in.triangleattributelist = NULL;
182   in.trianglearealist      = NULL;
183   in.segmentlist           = NULL;
184   in.holelist              = NULL;
185   in.regionlist            = NULL;
186   in.edgelist              = NULL;
187   in.edgemarkerlist        = NULL;
188   in.normlist              = NULL;
189 
190   /* triangulate */
191   mid.pointlist = NULL; /* Not needed if -N switch used. */
192   /* Not needed if -N switch used or number of point attributes is zero: */
193   mid.pointattributelist = NULL;
194   mid.pointmarkerlist    = NULL; /* Not needed if -N or -B switch used. */
195   mid.trianglelist       = NULL; /* Not needed if -E switch used. */
196   /* Not needed if -E switch used or number of triangle attributes is zero: */
197   mid.triangleattributelist = NULL;
198   mid.neighborlist          = NULL; /* Needed only if -n switch used. */
199   /* Needed only if segments are output (-p or -c) and -P not used: */
200   mid.segmentlist = NULL;
201   /* Needed only if segments are output (-p or -c) and -P and -B not used: */
202   mid.segmentmarkerlist = NULL;
203   mid.edgelist          = NULL; /* Needed only if -e switch used. */
204   mid.edgemarkerlist    = NULL; /* Needed if -e used and -B not used. */
205   mid.numberoftriangles = 0;
206 
207   /* Triangulate the points.  Switches are chosen to read and write a  */
208   /*   PSLG (p), preserve the convex hull (c), number everything from  */
209   /*   zero (z), assign a regional attribute to each element (A), and  */
210   /*   produce an edge list (e), a Voronoi diagram (v), and a triangle */
211   /*   neighbor list (n).                                            */
212   if (nselected_2 != 0) {  /* inactive processor */
213     char args[] = "npczQ"; /* c is needed ? */
214     triangulate(args, &in, &mid, (struct triangulateio *)NULL);
215     /* output .poly files for 'showme' */
216     if (!PETSC_TRUE) {
217       static int level = 1;
218       FILE      *file;
219       char       fname[32];
220 
221       PetscCall(PetscSNPrintf(fname, PETSC_STATIC_ARRAY_LENGTH(fname), "C%d_%d.poly", level, rank));
222       file = fopen(fname, "w");
223       /*First line: <# of vertices> <dimension (must be 2)> <# of attributes> <# of boundary markers (0 or 1)>*/
224       fprintf(file, "%d  %d  %d  %d\n", in.numberofpoints, 2, 0, 0);
225       /*Following lines: <vertex #> <x> <y> */
226       for (kk = 0, sid = 0; kk < in.numberofpoints; kk++, sid += 2) fprintf(file, "%d %e %e\n", kk, in.pointlist[sid], in.pointlist[sid + 1]);
227       /*One line: <# of segments> <# of boundary markers (0 or 1)> */
228       fprintf(file, "%d  %d\n", 0, 0);
229       /*Following lines: <segment #> <endpoint> <endpoint> [boundary marker] */
230       /* One line: <# of holes> */
231       fprintf(file, "%d\n", 0);
232       /* Following lines: <hole #> <x> <y> */
233       /* Optional line: <# of regional attributes and/or area constraints> */
234       /* Optional following lines: <region #> <x> <y> <attribute> <maximum area> */
235       fclose(file);
236 
237       /* elems */
238       PetscCall(PetscSNPrintf(fname, PETSC_STATIC_ARRAY_LENGTH(fname), "C%d_%d.ele", level, rank));
239       file = fopen(fname, "w");
240       /* First line: <# of triangles> <nodes per triangle> <# of attributes> */
241       fprintf(file, "%d %d %d\n", mid.numberoftriangles, 3, 0);
242       /* Remaining lines: <triangle #> <node> <node> <node> ... [attributes] */
243       for (kk = 0, sid = 0; kk < mid.numberoftriangles; kk++, sid += 3) fprintf(file, "%d %d %d %d\n", kk, mid.trianglelist[sid], mid.trianglelist[sid + 1], mid.trianglelist[sid + 2]);
244       fclose(file);
245 
246       PetscCall(PetscSNPrintf(fname, PETSC_STATIC_ARRAY_LENGTH(fname), "C%d_%d.node", level, rank));
247       file = fopen(fname, "w");
248       /* First line: <# of vertices> <dimension (must be 2)> <# of attributes> <# of boundary markers (0 or 1)> */
249       /* fprintf(file, "%d  %d  %d  %d\n",in.numberofpoints,2,0,0); */
250       fprintf(file, "%d  %d  %d  %d\n", nPlotPts, 2, 0, 0);
251       /*Following lines: <vertex #> <x> <y> */
252       for (kk = 0, sid = 0; kk < in.numberofpoints; kk++, sid += 2) fprintf(file, "%d %e %e\n", kk, in.pointlist[sid], in.pointlist[sid + 1]);
253 
254       sid /= 2;
255       for (jj = 0; jj < nFineLoc; jj++) {
256         PetscBool sel = PETSC_TRUE;
257         for (kk = 0; kk < nselected_2 && sel; kk++) {
258           PetscInt lid = selected_idx_2[kk];
259           if (lid == jj) sel = PETSC_FALSE;
260         }
261         if (sel) fprintf(file, "%d %e %e\n", sid++, coords[jj], coords[data_stride + jj]);
262       }
263       fclose(file);
264       PetscCheck(sid == nPlotPts, PETSC_COMM_SELF, PETSC_ERR_PLIB, "sid %d != nPlotPts %d", sid, nPlotPts);
265       level++;
266     }
267   }
268   { /* form P - setup some maps */
269     PetscInt clid, mm, *nTri, *node_tri;
270 
271     PetscCall(PetscMalloc2(nselected_2, &node_tri, nselected_2, &nTri));
272 
273     /* need list of triangles on node */
274     for (kk = 0; kk < nselected_2; kk++) nTri[kk] = 0;
275     for (tid = 0, kk = 0; tid < mid.numberoftriangles; tid++) {
276       for (jj = 0; jj < 3; jj++) {
277         PetscInt cid = mid.trianglelist[kk++];
278         if (nTri[cid] == 0) node_tri[cid] = tid;
279         nTri[cid]++;
280       }
281     }
282   #define EPS 1.e-12
283     /* find points and set prolongation */
284     for (mm = clid = 0; mm < nFineLoc; mm++) {
285       PetscBool ise;
286       PetscCall(PetscCDEmptyAt(agg_lists_1, mm, &ise));
287       if (!ise) {
288         const PetscInt lid = mm;
289         PetscScalar    AA[3][3];
290         PetscBLASInt   N = 3, NRHS = 1, LDA = 3, IPIV[3], LDB = 3, INFO;
291         PetscCDIntNd  *pos;
292 
293         PetscCall(PetscCDGetHeadPos(agg_lists_1, lid, &pos));
294         while (pos) {
295           PetscInt flid;
296           PetscCall(PetscCDIntNdGetID(pos, &flid));
297           PetscCall(PetscCDGetNextPos(agg_lists_1, lid, &pos));
298 
299           if (flid < nFineLoc) { /* could be a ghost */
300             PetscInt       bestTID    = -1;
301             PetscReal      best_alpha = 1.e10;
302             const PetscInt fgid       = flid + myFine0;
303             /* compute shape function for gid */
304             const PetscReal fcoord[3] = {coords[flid], coords[data_stride + flid], 1.0};
305             PetscBool       haveit    = PETSC_FALSE;
306             PetscScalar     alpha[3];
307             PetscInt        clids[3];
308 
309             /* look for it */
310             for (tid = node_tri[clid], jj = 0; jj < 5 && !haveit && tid != -1; jj++) {
311               for (tt = 0; tt < 3; tt++) {
312                 PetscInt cid2 = mid.trianglelist[3 * tid + tt];
313                 PetscInt lid2 = selected_idx_2[cid2];
314                 AA[tt][0]     = coords[lid2];
315                 AA[tt][1]     = coords[data_stride + lid2];
316                 AA[tt][2]     = 1.0;
317                 clids[tt]     = cid2; /* store for interp */
318               }
319 
320               for (tt = 0; tt < 3; tt++) alpha[tt] = (PetscScalar)fcoord[tt];
321 
322               /* SUBROUTINE DGESV(N, NRHS, A, LDA, IPIV, B, LDB, INFO) */
323               PetscCallBLAS("LAPACKgesv", LAPACKgesv_(&N, &NRHS, (PetscScalar *)AA, &LDA, IPIV, alpha, &LDB, &INFO));
324               {
325                 PetscBool have   = PETSC_TRUE;
326                 PetscReal lowest = 1.e10;
327                 for (tt = 0, idx = 0; tt < 3; tt++) {
328                   if (PetscRealPart(alpha[tt]) > (1.0 + EPS) || PetscRealPart(alpha[tt]) < -EPS) have = PETSC_FALSE;
329                   if (PetscRealPart(alpha[tt]) < lowest) {
330                     lowest = PetscRealPart(alpha[tt]);
331                     idx    = tt;
332                   }
333                 }
334                 haveit = have;
335               }
336               tid = mid.neighborlist[3 * tid + idx];
337             }
338 
339             if (!haveit) {
340               /* brute force */
341               for (tid = 0; tid < mid.numberoftriangles && !haveit; tid++) {
342                 for (tt = 0; tt < 3; tt++) {
343                   PetscInt cid2 = mid.trianglelist[3 * tid + tt];
344                   PetscInt lid2 = selected_idx_2[cid2];
345                   AA[tt][0]     = coords[lid2];
346                   AA[tt][1]     = coords[data_stride + lid2];
347                   AA[tt][2]     = 1.0;
348                   clids[tt]     = cid2; /* store for interp */
349                 }
350                 for (tt = 0; tt < 3; tt++) alpha[tt] = fcoord[tt];
351                 /* SUBROUTINE DGESV(N, NRHS, A, LDA, IPIV, B, LDB, INFO) */
352                 PetscCallBLAS("LAPACKgesv", LAPACKgesv_(&N, &NRHS, (PetscScalar *)AA, &LDA, IPIV, alpha, &LDB, &INFO));
353                 {
354                   PetscBool have  = PETSC_TRUE;
355                   PetscReal worst = 0.0, v;
356                   for (tt = 0; tt < 3 && have; tt++) {
357                     if (PetscRealPart(alpha[tt]) > 1.0 + EPS || PetscRealPart(alpha[tt]) < -EPS) have = PETSC_FALSE;
358                     if ((v = PetscAbs(PetscRealPart(alpha[tt]) - 0.5)) > worst) worst = v;
359                   }
360                   if (worst < best_alpha) {
361                     best_alpha = worst;
362                     bestTID    = tid;
363                   }
364                   haveit = have;
365                 }
366               }
367             }
368             if (!haveit) {
369               if (best_alpha > *a_worst_best) *a_worst_best = best_alpha;
370               /* use best one */
371               for (tt = 0; tt < 3; tt++) {
372                 PetscInt cid2 = mid.trianglelist[3 * bestTID + tt];
373                 PetscInt lid2 = selected_idx_2[cid2];
374                 AA[tt][0]     = coords[lid2];
375                 AA[tt][1]     = coords[data_stride + lid2];
376                 AA[tt][2]     = 1.0;
377                 clids[tt]     = cid2; /* store for interp */
378               }
379               for (tt = 0; tt < 3; tt++) alpha[tt] = fcoord[tt];
380               /* SUBROUTINE DGESV(N, NRHS, A, LDA, IPIV, B, LDB, INFO) */
381               PetscCallBLAS("LAPACKgesv", LAPACKgesv_(&N, &NRHS, (PetscScalar *)AA, &LDA, IPIV, alpha, &LDB, &INFO));
382             }
383 
384             /* put in row of P */
385             for (idx = 0; idx < 3; idx++) {
386               PetscScalar shp = alpha[idx];
387               if (PetscAbs(PetscRealPart(shp)) > 1.e-6) {
388                 PetscInt cgid = crsGID[clids[idx]];
389                 PetscInt jj = cgid * bs, ii = fgid * bs; /* need to gloalize */
390                 for (tt = 0; tt < bs; tt++, ii++, jj++) PetscCall(MatSetValues(a_Prol, 1, &ii, 1, &jj, &shp, INSERT_VALUES));
391               }
392             }
393           }
394         } /* aggregates iterations */
395         clid++;
396       } /* a coarse agg */
397     }   /* for all fine nodes */
398 
399     PetscCall(ISRestoreIndices(selected_2, &selected_idx_2));
400     PetscCall(MatAssemblyBegin(a_Prol, MAT_FINAL_ASSEMBLY));
401     PetscCall(MatAssemblyEnd(a_Prol, MAT_FINAL_ASSEMBLY));
402 
403     PetscCall(PetscFree2(node_tri, nTri));
404   }
405   free(mid.trianglelist);
406   free(mid.neighborlist);
407   free(mid.segmentlist);
408   free(mid.segmentmarkerlist);
409   free(mid.pointlist);
410   free(mid.pointmarkerlist);
411   PetscCall(PetscFree(in.pointlist));
412   PetscFunctionReturn(PETSC_SUCCESS);
413 #else
414   SETERRQ(PetscObjectComm((PetscObject)a_Prol), PETSC_ERR_PLIB, "configure with TRIANGLE to use geometric MG");
415 #endif
416 }
417 
418 /*
419    getGIDsOnSquareGraph - square graph, get
420 
421    Input Parameter:
422    . nselected_1 - selected local indices (includes ghosts in input Gmat1)
423    . clid_lid_1 - [nselected_1] lids of selected nodes
424    . Gmat1 - graph that goes with 'selected_1'
425    Output Parameter:
426    . a_selected_2 - selected local indices (includes ghosts in output a_Gmat_2)
427    . a_Gmat_2 - graph that is squared of 'Gmat_1'
428    . a_crsGID[a_selected_2.size()] - map of global IDs of coarse grid nodes
429 */
430 static PetscErrorCode getGIDsOnSquareGraph(PC pc, PetscInt nselected_1, const PetscInt clid_lid_1[], const Mat Gmat1, IS *a_selected_2, Mat *a_Gmat_2, PetscInt **a_crsGID)
431 {
432   PetscMPIInt size;
433   PetscInt   *crsGID, kk, my0, Iend, nloc;
434   MPI_Comm    comm;
435 
436   PetscFunctionBegin;
437   PetscCall(PetscObjectGetComm((PetscObject)Gmat1, &comm));
438   PetscCallMPI(MPI_Comm_size(comm, &size));
439   PetscCall(MatGetOwnershipRange(Gmat1, &my0, &Iend)); /* AIJ */
440   nloc = Iend - my0;                                   /* this does not change */
441 
442   if (size == 1) { /* not much to do in serial */
443     PetscCall(PetscMalloc1(nselected_1, &crsGID));
444     for (kk = 0; kk < nselected_1; kk++) crsGID[kk] = kk;
445     *a_Gmat_2 = NULL;
446     PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nselected_1, clid_lid_1, PETSC_COPY_VALUES, a_selected_2));
447   } else {
448     PetscInt     idx, num_fine_ghosts, num_crs_ghost, myCrs0;
449     Mat_MPIAIJ  *mpimat2;
450     Mat          Gmat2;
451     Vec          locState;
452     PetscScalar *cpcol_state;
453 
454     /* scan my coarse zero gid, set 'lid_state' with coarse GID */
455     kk = nselected_1;
456     PetscCallMPI(MPI_Scan(&kk, &myCrs0, 1, MPIU_INT, MPI_SUM, comm));
457     myCrs0 -= nselected_1;
458 
459     if (a_Gmat_2) { /* output */
460       /* grow graph to get wider set of selected vertices to cover fine grid, invalidates 'llist' */
461       PetscCall(PCGAMGSquareGraph_GAMG(pc, Gmat1, &Gmat2));
462       *a_Gmat_2 = Gmat2;  /* output */
463     } else Gmat2 = Gmat1; /* use local to get crsGIDs at least */
464     /* get coarse grid GIDS for selected (locals and ghosts) */
465     mpimat2 = (Mat_MPIAIJ *)Gmat2->data;
466     PetscCall(MatCreateVecs(Gmat2, &locState, NULL));
467     PetscCall(VecSet(locState, (PetscScalar)(PetscReal)(-1))); /* set with UNKNOWN state */
468     for (kk = 0; kk < nselected_1; kk++) {
469       PetscInt    fgid = clid_lid_1[kk] + my0;
470       PetscScalar v    = (PetscScalar)(kk + myCrs0);
471       PetscCall(VecSetValues(locState, 1, &fgid, &v, INSERT_VALUES)); /* set with PID */
472     }
473     PetscCall(VecAssemblyBegin(locState));
474     PetscCall(VecAssemblyEnd(locState));
475     PetscCall(VecScatterBegin(mpimat2->Mvctx, locState, mpimat2->lvec, INSERT_VALUES, SCATTER_FORWARD));
476     PetscCall(VecScatterEnd(mpimat2->Mvctx, locState, mpimat2->lvec, INSERT_VALUES, SCATTER_FORWARD));
477     PetscCall(VecGetLocalSize(mpimat2->lvec, &num_fine_ghosts));
478     PetscCall(VecGetArray(mpimat2->lvec, &cpcol_state));
479     for (kk = 0, num_crs_ghost = 0; kk < num_fine_ghosts; kk++) {
480       if ((PetscInt)PetscRealPart(cpcol_state[kk]) != -1) num_crs_ghost++;
481     }
482     PetscCall(PetscMalloc1(nselected_1 + num_crs_ghost, &crsGID)); /* output */
483     {
484       PetscInt *selected_set;
485       PetscCall(PetscMalloc1(nselected_1 + num_crs_ghost, &selected_set));
486       /* do ghost of 'crsGID' */
487       for (kk = 0, idx = nselected_1; kk < num_fine_ghosts; kk++) {
488         if ((PetscInt)PetscRealPart(cpcol_state[kk]) != -1) {
489           PetscInt cgid     = (PetscInt)PetscRealPart(cpcol_state[kk]);
490           selected_set[idx] = nloc + kk;
491           crsGID[idx++]     = cgid;
492         }
493       }
494       PetscCheck(idx == (nselected_1 + num_crs_ghost), PETSC_COMM_SELF, PETSC_ERR_PLIB, "idx %" PetscInt_FMT " != (nselected_1 %" PetscInt_FMT " + num_crs_ghost %" PetscInt_FMT ")", idx, nselected_1, num_crs_ghost);
495       PetscCall(VecRestoreArray(mpimat2->lvec, &cpcol_state));
496       /* do locals in 'crsGID' */
497       PetscCall(VecGetArray(locState, &cpcol_state));
498       for (kk = 0, idx = 0; kk < nloc; kk++) {
499         if ((PetscInt)PetscRealPart(cpcol_state[kk]) != -1) {
500           PetscInt cgid     = (PetscInt)PetscRealPart(cpcol_state[kk]);
501           selected_set[idx] = kk;
502           crsGID[idx++]     = cgid;
503         }
504       }
505       PetscCheck(idx == nselected_1, PETSC_COMM_SELF, PETSC_ERR_PLIB, "idx %" PetscInt_FMT " != nselected_1 %" PetscInt_FMT, idx, nselected_1);
506       PetscCall(VecRestoreArray(locState, &cpcol_state));
507 
508       if (a_selected_2 != NULL) { /* output */
509         PetscCall(ISCreateGeneral(PETSC_COMM_SELF, (nselected_1 + num_crs_ghost), selected_set, PETSC_OWN_POINTER, a_selected_2));
510       } else {
511         PetscCall(PetscFree(selected_set));
512       }
513     }
514     PetscCall(VecDestroy(&locState));
515   }
516   *a_crsGID = crsGID; /* output */
517   PetscFunctionReturn(PETSC_SUCCESS);
518 }
519 
520 PetscErrorCode PCGAMGCreateGraph_GEO(PC pc, Mat Amat, Mat *a_Gmat)
521 {
522   PC_MG          *mg      = (PC_MG *)pc->data;
523   PC_GAMG        *pc_gamg = (PC_GAMG *)mg->innerctx;
524   const PetscReal vfilter = pc_gamg->threshold[0];
525 
526   PetscFunctionBegin;
527   PetscCall(MatCreateGraph(Amat, PETSC_TRUE, PETSC_TRUE, vfilter, a_Gmat));
528   PetscFunctionReturn(PETSC_SUCCESS);
529 }
530 
531 /*
532    PCGAMGCoarsen_GEO
533 
534   Input Parameter:
535    . a_pc - this
536    . a_Gmat - graph
537   Output Parameter:
538    . a_llist_parent - linked list from selected indices for data locality only
539 */
540 PetscErrorCode PCGAMGCoarsen_GEO(PC a_pc, Mat *a_Gmat, PetscCoarsenData **a_llist_parent)
541 {
542   PetscInt   Istart, Iend, nloc, kk, Ii, ncols;
543   IS         perm;
544   GAMGNode  *gnodes;
545   PetscInt  *permute;
546   Mat        Gmat = *a_Gmat;
547   MPI_Comm   comm;
548   MatCoarsen crs;
549 
550   PetscFunctionBegin;
551   PetscCall(PetscObjectGetComm((PetscObject)a_pc, &comm));
552 
553   PetscCall(MatGetOwnershipRange(Gmat, &Istart, &Iend));
554   nloc = (Iend - Istart);
555 
556   /* create random permutation with sort for geo-mg */
557   PetscCall(PetscMalloc1(nloc, &gnodes));
558   PetscCall(PetscMalloc1(nloc, &permute));
559 
560   for (Ii = Istart; Ii < Iend; Ii++) { /* locals only? */
561     PetscCall(MatGetRow(Gmat, Ii, &ncols, NULL, NULL));
562     {
563       PetscInt lid       = Ii - Istart;
564       gnodes[lid].lid    = lid;
565       gnodes[lid].degree = ncols;
566     }
567     PetscCall(MatRestoreRow(Gmat, Ii, &ncols, NULL, NULL));
568   }
569   if (PETSC_TRUE) {
570     PetscRandom rand;
571     PetscBool  *bIndexSet;
572     PetscReal   rr;
573     PetscInt    iSwapIndex;
574 
575     PetscCall(PetscRandomCreate(comm, &rand));
576     PetscCall(PetscCalloc1(nloc, &bIndexSet));
577     for (Ii = 0; Ii < nloc; Ii++) {
578       PetscCall(PetscRandomGetValueReal(rand, &rr));
579       iSwapIndex = (PetscInt)(rr * nloc);
580       if (!bIndexSet[iSwapIndex] && iSwapIndex != Ii) {
581         GAMGNode iTemp        = gnodes[iSwapIndex];
582         gnodes[iSwapIndex]    = gnodes[Ii];
583         gnodes[Ii]            = iTemp;
584         bIndexSet[Ii]         = PETSC_TRUE;
585         bIndexSet[iSwapIndex] = PETSC_TRUE;
586       }
587     }
588     PetscCall(PetscRandomDestroy(&rand));
589     PetscCall(PetscFree(bIndexSet));
590   }
591   /* only sort locals */
592   qsort(gnodes, nloc, sizeof(GAMGNode), petsc_geo_mg_compare);
593   /* create IS of permutation */
594   for (kk = 0; kk < nloc; kk++) permute[kk] = gnodes[kk].lid; /* locals only */
595   PetscCall(PetscFree(gnodes));
596   PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nloc, permute, PETSC_OWN_POINTER, &perm));
597 
598   /* get MIS aggs */
599 
600   PetscCall(MatCoarsenCreate(comm, &crs));
601   PetscCall(MatCoarsenSetType(crs, MATCOARSENMIS));
602   PetscCall(MatCoarsenSetGreedyOrdering(crs, perm));
603   PetscCall(MatCoarsenSetAdjacency(crs, Gmat));
604   PetscCall(MatCoarsenSetStrictAggs(crs, PETSC_FALSE));
605   PetscCall(MatCoarsenApply(crs));
606   PetscCall(MatCoarsenGetData(crs, a_llist_parent));
607   PetscCall(MatCoarsenDestroy(&crs));
608 
609   PetscCall(ISDestroy(&perm));
610 
611   PetscFunctionReturn(PETSC_SUCCESS);
612 }
613 
614 /*
615  PCGAMGProlongator_GEO
616 
617  Input Parameter:
618  . pc - this
619  . Amat - matrix on this fine level
620  . Graph - used to get ghost data for nodes in
621  . selected_1 - [nselected]
622  . agg_lists - [nselected]
623  Output Parameter:
624  . a_P_out - prolongation operator to the next level
625  */
626 PetscErrorCode PCGAMGProlongator_GEO(PC pc, Mat Amat, Mat Gmat, PetscCoarsenData *agg_lists, Mat *a_P_out)
627 {
628   PC_MG          *mg      = (PC_MG *)pc->data;
629   PC_GAMG        *pc_gamg = (PC_GAMG *)mg->innerctx;
630   const PetscInt  dim = pc_gamg->data_cell_cols, data_cols = pc_gamg->data_cell_cols;
631   PetscInt        Istart, Iend, nloc, my0, jj, kk, ncols, nLocalSelected, bs, *clid_flid;
632   Mat             Prol;
633   PetscMPIInt     rank, size;
634   MPI_Comm        comm;
635   IS              selected_2, selected_1;
636   const PetscInt *selected_idx;
637   MatType         mtype;
638 
639   PetscFunctionBegin;
640   PetscCall(PetscObjectGetComm((PetscObject)Amat, &comm));
641 
642   PetscCallMPI(MPI_Comm_rank(comm, &rank));
643   PetscCallMPI(MPI_Comm_size(comm, &size));
644   PetscCall(MatGetOwnershipRange(Amat, &Istart, &Iend));
645   PetscCall(MatGetBlockSize(Amat, &bs));
646   nloc = (Iend - Istart) / bs;
647   my0  = Istart / bs;
648   PetscCheck((Iend - Istart) % bs == 0, PETSC_COMM_SELF, PETSC_ERR_PLIB, "(Iend %" PetscInt_FMT " - Istart %" PetscInt_FMT ") %% bs %" PetscInt_FMT, Iend, Istart, bs);
649 
650   /* get 'nLocalSelected' */
651   PetscCall(PetscCDGetMIS(agg_lists, &selected_1));
652   PetscCall(ISGetSize(selected_1, &jj));
653   PetscCall(PetscMalloc1(jj, &clid_flid));
654   PetscCall(ISGetIndices(selected_1, &selected_idx));
655   for (kk = 0, nLocalSelected = 0; kk < jj; kk++) {
656     PetscInt lid = selected_idx[kk];
657     if (lid < nloc) {
658       PetscCall(MatGetRow(Gmat, lid + my0, &ncols, NULL, NULL));
659       if (ncols > 1) clid_flid[nLocalSelected++] = lid; /* filter out singletons */
660       PetscCall(MatRestoreRow(Gmat, lid + my0, &ncols, NULL, NULL));
661     }
662   }
663   PetscCall(ISRestoreIndices(selected_1, &selected_idx));
664   PetscCall(ISDestroy(&selected_1)); /* this is selected_1 in serial */
665 
666   /* create prolongator  matrix */
667   PetscCall(MatGetType(Amat, &mtype));
668   PetscCall(MatCreate(comm, &Prol));
669   PetscCall(MatSetSizes(Prol, nloc * bs, nLocalSelected * bs, PETSC_DETERMINE, PETSC_DETERMINE));
670   PetscCall(MatSetBlockSizes(Prol, bs, bs));
671   PetscCall(MatSetType(Prol, mtype));
672   PetscCall(MatSeqAIJSetPreallocation(Prol, 3 * data_cols, NULL));
673   PetscCall(MatMPIAIJSetPreallocation(Prol, 3 * data_cols, NULL, 3 * data_cols, NULL));
674 
675   /* can get all points "removed" - but not on geomg */
676   PetscCall(MatGetSize(Prol, &kk, &jj));
677   if (!jj) {
678     PetscCall(PetscInfo(pc, "ERROE: no selected points on coarse grid\n"));
679     PetscCall(PetscFree(clid_flid));
680     PetscCall(MatDestroy(&Prol));
681     *a_P_out = NULL; /* out */
682     PetscFunctionReturn(PETSC_SUCCESS);
683   }
684 
685   {
686     PetscReal *coords;
687     PetscInt   data_stride;
688     PetscInt  *crsGID = NULL;
689     Mat        Gmat2;
690 
691     PetscCheck(dim == data_cols, PETSC_COMM_SELF, PETSC_ERR_PLIB, "dim %" PetscInt_FMT " != data_cols %" PetscInt_FMT, dim, data_cols);
692     /* grow ghost data for better coarse grid cover of fine grid */
693     /* messy method, squares graph and gets some data */
694     PetscCall(getGIDsOnSquareGraph(pc, nLocalSelected, clid_flid, Gmat, &selected_2, &Gmat2, &crsGID));
695     /* llist is now not valid wrt squared graph, but will work as iterator in 'triangulateAndFormProl' */
696     /* create global vector of coorindates in 'coords' */
697     if (size > 1) {
698       PetscCall(PCGAMGGetDataWithGhosts(Gmat2, dim, pc_gamg->data, &data_stride, &coords));
699     } else {
700       coords      = (PetscReal *)pc_gamg->data;
701       data_stride = pc_gamg->data_sz / pc_gamg->data_cell_cols;
702     }
703     PetscCall(MatDestroy(&Gmat2));
704 
705     /* triangulate */
706     {
707       PetscReal metric, tm;
708 
709       PetscCheck(dim == 2, comm, PETSC_ERR_PLIB, "3D not implemented for 'geo' AMG");
710       PetscCall(triangulateAndFormProl(selected_2, data_stride, coords, nLocalSelected, clid_flid, agg_lists, crsGID, bs, Prol, &metric));
711       PetscCall(PetscFree(crsGID));
712 
713       /* clean up and create coordinates for coarse grid (output) */
714       if (size > 1) PetscCall(PetscFree(coords));
715 
716       PetscCall(MPIU_Allreduce(&metric, &tm, 1, MPIU_REAL, MPIU_MAX, comm));
717       if (tm > 1.) { /* needs to be globalized - should not happen */
718         PetscCall(PetscInfo(pc, " failed metric for coarse grid %e\n", (double)tm));
719         PetscCall(MatDestroy(&Prol));
720       } else if (metric > .0) {
721         PetscCall(PetscInfo(pc, "worst metric for coarse grid = %e\n", (double)metric));
722       }
723     }
724     { /* create next coords - output */
725       PetscReal *crs_crds;
726       PetscCall(PetscMalloc1(dim * nLocalSelected, &crs_crds));
727       for (kk = 0; kk < nLocalSelected; kk++) { /* grab local select nodes to promote - output */
728         PetscInt lid = clid_flid[kk];
729         for (jj = 0; jj < dim; jj++) crs_crds[jj * nLocalSelected + kk] = pc_gamg->data[jj * nloc + lid];
730       }
731 
732       PetscCall(PetscFree(pc_gamg->data));
733       pc_gamg->data    = crs_crds; /* out */
734       pc_gamg->data_sz = dim * nLocalSelected;
735     }
736     PetscCall(ISDestroy(&selected_2));
737   }
738 
739   *a_P_out = Prol; /* out */
740   PetscCall(PetscFree(clid_flid));
741 
742   PetscFunctionReturn(PETSC_SUCCESS);
743 }
744 
745 static PetscErrorCode PCDestroy_GAMG_GEO(PC pc)
746 {
747   PetscFunctionBegin;
748   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCSetCoordinates_C", NULL));
749   PetscFunctionReturn(PETSC_SUCCESS);
750 }
751 
752 /*
753  PCCreateGAMG_GEO
754 
755   Input Parameter:
756    . pc -
757 */
758 PetscErrorCode PCCreateGAMG_GEO(PC pc)
759 {
760   PC_MG   *mg      = (PC_MG *)pc->data;
761   PC_GAMG *pc_gamg = (PC_GAMG *)mg->innerctx;
762 
763   PetscFunctionBegin;
764   pc_gamg->ops->setfromoptions = PCSetFromOptions_GEO;
765   pc_gamg->ops->destroy        = PCDestroy_GAMG_GEO;
766   /* reset does not do anything; setup not virtual */
767 
768   /* set internal function pointers */
769   pc_gamg->ops->creategraph       = PCGAMGCreateGraph_GEO;
770   pc_gamg->ops->coarsen           = PCGAMGCoarsen_GEO;
771   pc_gamg->ops->prolongator       = PCGAMGProlongator_GEO;
772   pc_gamg->ops->optprolongator    = NULL;
773   pc_gamg->ops->createdefaultdata = PCSetData_GEO;
774 
775   PetscCall(PetscObjectComposeFunction((PetscObject)pc, "PCSetCoordinates_C", PCSetCoordinates_GEO));
776   PetscFunctionReturn(PETSC_SUCCESS);
777 }
778