xref: /petsc/src/ksp/pc/impls/gamg/gamg.c (revision bb74729cafbfcb6265ea097979a2a2cac4d11507)
1 /*
2  GAMG geometric-algebric multigrid PC - Mark Adams 2011
3  */
4 #include "petsc-private/matimpl.h"
5 #include <../src/ksp/pc/impls/gamg/gamg.h>           /*I "petscpc.h" I*/
6 #include <petsc-private/kspimpl.h>
7 #include <assert.h>
8 
9 #if defined PETSC_GAMG_USE_LOG
10 PetscLogEvent petsc_gamg_setup_events[NUM_SET];
11 #endif
12 
13 #if defined PETSC_USE_LOG
14 PetscLogEvent PC_GAMGGgraph_AGG;
15 PetscLogEvent PC_GAMGGgraph_GEO;
16 PetscLogEvent PC_GAMGCoarsen_AGG;
17 PetscLogEvent PC_GAMGCoarsen_GEO;
18 PetscLogEvent PC_GAMGProlongator_AGG;
19 PetscLogEvent PC_GAMGProlongator_GEO;
20 PetscLogEvent PC_GAMGOptprol_AGG;
21 PetscLogEvent PC_GAMGKKTProl_AGG;
22 #endif
23 
24 #define GAMG_MAXLEVELS 30
25 
26 /* #define GAMG_STAGES */
27 #if (defined PETSC_GAMG_USE_LOG && defined GAMG_STAGES)
28 static PetscLogStage gamg_stages[GAMG_MAXLEVELS];
29 #endif
30 
31 static PetscFunctionList GAMGList = 0;
32 
33 /* ----------------------------------------------------------------------------- */
34 #undef __FUNCT__
35 #define __FUNCT__ "PCReset_GAMG"
36 PetscErrorCode PCReset_GAMG(PC pc)
37 {
38   PetscErrorCode ierr;
39   PC_MG          *mg      = (PC_MG*)pc->data;
40   PC_GAMG        *pc_gamg = (PC_GAMG*)mg->innerctx;
41 
42   PetscFunctionBegin;
43   if (pc_gamg->data) { /* this should not happen, cleaned up in SetUp */
44     PetscPrintf(((PetscObject)pc)->comm,"***[%d]%s this should not happen, cleaned up in SetUp\n",0,__FUNCT__);
45     ierr = PetscFree(pc_gamg->data);CHKERRQ(ierr);
46   }
47   pc_gamg->data = NULL; pc_gamg->data_sz = 0;
48 
49   if (pc_gamg->orig_data) {
50     ierr = PetscFree(pc_gamg->orig_data);CHKERRQ(ierr);
51   }
52   PetscFunctionReturn(0);
53 }
54 
55 /* private 2x2 Mat Nest for Stokes */
56 typedef struct {
57   Mat A11,A21,A12,Amat;
58   IS  prim_is,constr_is;
59 } GAMGKKTMat;
60 
61 #undef __FUNCT__
62 #define __FUNCT__ "GAMGKKTMatCreate"
63 static PetscErrorCode GAMGKKTMatCreate(Mat A, PetscBool iskkt, GAMGKKTMat *out)
64 {
65   PetscFunctionBegin;
66   out->Amat = A;
67   if (iskkt) {
68     PetscErrorCode ierr;
69     IS             is_constraint, is_prime;
70     PetscInt       nmin,nmax;
71 
72     ierr = MatGetOwnershipRange(A, &nmin, &nmax);CHKERRQ(ierr);
73     ierr = MatFindZeroDiagonals(A, &is_constraint);CHKERRQ(ierr);
74     ierr = ISComplement(is_constraint, nmin, nmax, &is_prime);CHKERRQ(ierr);
75 
76     out->prim_is   = is_prime;
77     out->constr_is = is_constraint;
78 
79     ierr = MatGetSubMatrix(A, is_prime, is_prime,      MAT_INITIAL_MATRIX, &out->A11);CHKERRQ(ierr);
80     ierr = MatGetSubMatrix(A, is_prime, is_constraint, MAT_INITIAL_MATRIX, &out->A12);CHKERRQ(ierr);
81     ierr = MatGetSubMatrix(A, is_constraint, is_prime, MAT_INITIAL_MATRIX, &out->A21);CHKERRQ(ierr);
82   } else {
83     out->A11       = A;
84     out->A21       = NULL;
85     out->A12       = NULL;
86     out->prim_is   = NULL;
87     out->constr_is = NULL;
88   }
89   PetscFunctionReturn(0);
90 }
91 
92 #undef __FUNCT__
93 #define __FUNCT__ "GAMGKKTMatDestroy"
94 static PetscErrorCode GAMGKKTMatDestroy(GAMGKKTMat *mat)
95 {
96   PetscErrorCode ierr;
97 
98   PetscFunctionBegin;
99   if (mat->A11 && mat->A11 != mat->Amat) {
100     ierr = MatDestroy(&mat->A11);CHKERRQ(ierr);
101   }
102   ierr = MatDestroy(&mat->A21);CHKERRQ(ierr);
103   ierr = MatDestroy(&mat->A12);CHKERRQ(ierr);
104 
105   ierr = ISDestroy(&mat->prim_is);CHKERRQ(ierr);
106   ierr = ISDestroy(&mat->constr_is);CHKERRQ(ierr);
107   PetscFunctionReturn(0);
108 }
109 
110 /* -------------------------------------------------------------------------- */
111 /*
112    createLevel: create coarse op with RAP.  repartition and/or reduce number
113      of active processors.
114 
115    Input Parameter:
116    . pc - parameters + side effect: coarse data in 'pc_gamg->data' and
117           'pc_gamg->data_sz' are changed via repartitioning/reduction.
118    . Amat_fine - matrix on this fine (k) level
119    . cr_bs - coarse block size
120    . isLast -
121    . stokes -
122    In/Output Parameter:
123    . a_P_inout - prolongation operator to the next level (k-->k-1)
124    . a_nactive_proc - number of active procs
125    Output Parameter:
126    . a_Amat_crs - coarse matrix that is created (k-1)
127 */
128 
129 #undef __FUNCT__
130 #define __FUNCT__ "createLevel"
131 static PetscErrorCode createLevel(const PC pc,const Mat Amat_fine,const PetscInt cr_bs,const PetscBool isLast,const PetscBool stokes,Mat *a_P_inout,Mat *a_Amat_crs,PetscMPIInt *a_nactive_proc)
132 {
133   PetscErrorCode  ierr;
134   PC_MG           *mg         = (PC_MG*)pc->data;
135   PC_GAMG         *pc_gamg    = (PC_GAMG*)mg->innerctx;
136   const PetscBool repart      = pc_gamg->repart;
137   const PetscInt  min_eq_proc = pc_gamg->min_eq_proc, coarse_max = pc_gamg->coarse_eq_limit;
138   Mat             Cmat,Pold=*a_P_inout;
139   MPI_Comm        wcomm = ((PetscObject)Amat_fine)->comm;
140   PetscMPIInt     rank,size,new_size,nactive=*a_nactive_proc;
141   PetscInt        ncrs_eq,ncrs_prim,f_bs;
142 
143   PetscFunctionBegin;
144   ierr = MPI_Comm_rank(wcomm, &rank);CHKERRQ(ierr);
145   ierr = MPI_Comm_size(wcomm, &size);CHKERRQ(ierr);
146   ierr = MatGetBlockSize(Amat_fine, &f_bs);CHKERRQ(ierr);
147   /* RAP */
148   ierr = MatPtAP(Amat_fine, Pold, MAT_INITIAL_MATRIX, 2.0, &Cmat);CHKERRQ(ierr);
149 
150   /* set 'ncrs_prim' (nodes), 'ncrs_eq' (equations)*/
151   ncrs_prim = pc_gamg->data_sz/pc_gamg->data_cell_cols/pc_gamg->data_cell_rows;
152   assert(pc_gamg->data_sz%(pc_gamg->data_cell_cols*pc_gamg->data_cell_rows)==0);
153   ierr = MatGetLocalSize(Cmat, &ncrs_eq, NULL);CHKERRQ(ierr);
154 
155   /* get number of PEs to make active 'new_size', reduce, can be any integer 1-P */
156   {
157     PetscInt ncrs_eq_glob;
158     ierr     = MatGetSize(Cmat, &ncrs_eq_glob, NULL);CHKERRQ(ierr);
159     new_size = (PetscMPIInt)((float)ncrs_eq_glob/(float)min_eq_proc + 0.5); /* hardwire min. number of eq/proc */
160     if (new_size == 0 || ncrs_eq_glob < coarse_max) new_size = 1;
161     else if (new_size >= nactive) new_size = nactive; /* no change, rare */
162     if (isLast) new_size = 1;
163   }
164 
165   if (!repart && new_size==nactive) *a_Amat_crs = Cmat; /* output - no repartitioning or reduction - could bail here */
166   else {
167     const PetscInt *idx,ndata_rows=pc_gamg->data_cell_rows,ndata_cols=pc_gamg->data_cell_cols,node_data_sz=ndata_rows*ndata_cols;
168     PetscInt       *counts,*newproc_idx,ii,jj,kk,strideNew,*tidx,ncrs_prim_new,ncrs_eq_new,nloc_old;
169     IS             is_eq_newproc,is_eq_newproc_prim,is_eq_num,is_eq_num_prim,isscat,new_eq_indices;
170     VecScatter     vecscat;
171     PetscScalar    *array;
172     Vec            src_crd, dest_crd;
173 
174     nloc_old = ncrs_eq/cr_bs; assert(ncrs_eq%cr_bs==0);
175 #if defined PETSC_GAMG_USE_LOG
176     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET12],0,0,0,0);CHKERRQ(ierr);
177 #endif
178     /* make 'is_eq_newproc' */
179     ierr = PetscMalloc(size*sizeof(PetscInt), &counts);CHKERRQ(ierr);
180     if (repart && !stokes) {
181       /* Repartition Cmat_{k} and move colums of P^{k}_{k-1} and coordinates of primal part accordingly */
182       Mat adj;
183 
184       if (pc_gamg->verbose>0) {
185         if (pc_gamg->verbose==1) PetscPrintf(wcomm,"\t[%d]%s repartition: size (active): %d --> %d, neq = %d\n",rank,__FUNCT__,*a_nactive_proc,new_size,ncrs_eq);
186         else {
187           PetscInt n;
188           ierr = MPI_Allreduce(&ncrs_eq, &n, 1, MPIU_INT, MPI_SUM, wcomm);CHKERRQ(ierr);
189           PetscPrintf(wcomm,"\t[%d]%s repartition: size (active): %d --> %d, neq = %d\n",rank,__FUNCT__,*a_nactive_proc,new_size,n);
190         }
191       }
192 
193       /* get 'adj' */
194       if (cr_bs == 1) {
195         ierr = MatConvert(Cmat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj);CHKERRQ(ierr);
196       } else {
197         /* make a scalar matrix to partition (no Stokes here) */
198         Mat               tMat;
199         PetscInt          Istart_crs,Iend_crs,ncols,jj,Ii;
200         const PetscScalar *vals;
201         const PetscInt    *idx;
202         PetscInt          *d_nnz, *o_nnz, M, N;
203         static PetscInt   llev = 0;
204 
205         ierr = PetscMalloc(ncrs_prim*sizeof(PetscInt), &d_nnz);CHKERRQ(ierr);
206         ierr = PetscMalloc(ncrs_prim*sizeof(PetscInt), &o_nnz);CHKERRQ(ierr);
207         ierr = MatGetOwnershipRange(Cmat, &Istart_crs, &Iend_crs);CHKERRQ(ierr);
208         ierr = MatGetSize(Cmat, &M, &N);CHKERRQ(ierr);
209         for (Ii = Istart_crs, jj = 0; Ii < Iend_crs; Ii += cr_bs, jj++) {
210           ierr      = MatGetRow(Cmat,Ii,&ncols,0,0);CHKERRQ(ierr);
211           d_nnz[jj] = ncols/cr_bs;
212           o_nnz[jj] = ncols/cr_bs;
213           ierr      = MatRestoreRow(Cmat,Ii,&ncols,0,0);CHKERRQ(ierr);
214           if (d_nnz[jj] > ncrs_prim) d_nnz[jj] = ncrs_prim;
215           if (o_nnz[jj] > (M/cr_bs-ncrs_prim)) o_nnz[jj] = M/cr_bs-ncrs_prim;
216         }
217 
218         ierr = MatCreate(wcomm, &tMat);CHKERRQ(ierr);
219         ierr = MatSetSizes(tMat, ncrs_prim, ncrs_prim,PETSC_DETERMINE, PETSC_DETERMINE);CHKERRQ(ierr);
220         ierr = MatSetType(tMat,MATAIJ);CHKERRQ(ierr);
221         ierr = MatSeqAIJSetPreallocation(tMat,0,d_nnz);CHKERRQ(ierr);
222         ierr = MatMPIAIJSetPreallocation(tMat,0,d_nnz,0,o_nnz);CHKERRQ(ierr);
223         ierr = PetscFree(d_nnz);CHKERRQ(ierr);
224         ierr = PetscFree(o_nnz);CHKERRQ(ierr);
225 
226         for (ii = Istart_crs; ii < Iend_crs; ii++) {
227           PetscInt dest_row = ii/cr_bs;
228           ierr = MatGetRow(Cmat,ii,&ncols,&idx,&vals);CHKERRQ(ierr);
229           for (jj = 0; jj < ncols; jj++) {
230             PetscInt    dest_col = idx[jj]/cr_bs;
231             PetscScalar v        = 1.0;
232             ierr = MatSetValues(tMat,1,&dest_row,1,&dest_col,&v,ADD_VALUES);CHKERRQ(ierr);
233           }
234           ierr = MatRestoreRow(Cmat,ii,&ncols,&idx,&vals);CHKERRQ(ierr);
235         }
236         ierr = MatAssemblyBegin(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
237         ierr = MatAssemblyEnd(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
238 
239         if (llev++ == -1) {
240           PetscViewer viewer; char fname[32];
241           ierr = PetscSNPrintf(fname,sizeof(fname),"part_mat_%D.mat",llev);CHKERRQ(ierr);
242           PetscViewerBinaryOpen(wcomm,fname,FILE_MODE_WRITE,&viewer);
243           ierr = MatView(tMat, viewer);CHKERRQ(ierr);
244           ierr = PetscViewerDestroy(&viewer);CHKERRQ(ierr);
245         }
246 
247         ierr = MatConvert(tMat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj);CHKERRQ(ierr);
248 
249         ierr = MatDestroy(&tMat);CHKERRQ(ierr);
250       } /* create 'adj' */
251 
252       { /* partition: get newproc_idx */
253         char            prefix[256];
254         const char      *pcpre;
255         const PetscInt  *is_idx;
256         MatPartitioning mpart;
257         IS              proc_is;
258         PetscInt        targetPE;
259 
260         ierr = MatPartitioningCreate(wcomm, &mpart);CHKERRQ(ierr);
261         ierr = MatPartitioningSetAdjacency(mpart, adj);CHKERRQ(ierr);
262         ierr = PCGetOptionsPrefix(pc, &pcpre);CHKERRQ(ierr);
263         ierr = PetscSNPrintf(prefix,sizeof(prefix),"%spc_gamg_",pcpre ? pcpre : "");CHKERRQ(ierr);
264         ierr = PetscObjectSetOptionsPrefix((PetscObject)mpart,prefix);CHKERRQ(ierr);
265         ierr = MatPartitioningSetFromOptions(mpart);CHKERRQ(ierr);
266         ierr = MatPartitioningSetNParts(mpart, new_size);CHKERRQ(ierr);
267         ierr = MatPartitioningApply(mpart, &proc_is);CHKERRQ(ierr);
268         ierr = MatPartitioningDestroy(&mpart);CHKERRQ(ierr);
269 
270         /* collect IS info */
271         ierr     = PetscMalloc(ncrs_eq*sizeof(PetscInt), &newproc_idx);CHKERRQ(ierr);
272         ierr     = ISGetIndices(proc_is, &is_idx);CHKERRQ(ierr);
273         targetPE = 1; /* bring to "front" of machine */
274         /*targetPE = size/new_size;*/ /* spread partitioning across machine */
275         for (kk = jj = 0 ; kk < nloc_old ; kk++) {
276           for (ii = 0 ; ii < cr_bs ; ii++, jj++) {
277             newproc_idx[jj] = is_idx[kk] * targetPE; /* distribution */
278           }
279         }
280         ierr = ISRestoreIndices(proc_is, &is_idx);CHKERRQ(ierr);
281         ierr = ISDestroy(&proc_is);CHKERRQ(ierr);
282       }
283       ierr = MatDestroy(&adj);CHKERRQ(ierr);
284 
285       ierr = ISCreateGeneral(wcomm, ncrs_eq, newproc_idx, PETSC_COPY_VALUES, &is_eq_newproc);CHKERRQ(ierr);
286       if (newproc_idx != 0) {
287         ierr = PetscFree(newproc_idx);CHKERRQ(ierr);
288       }
289     } else { /* simple aggreagtion of parts -- 'is_eq_newproc' */
290 
291       PetscInt rfactor,targetPE;
292       /* find factor */
293       if (new_size == 1) rfactor = size; /* easy */
294       else {
295         PetscReal best_fact = 0.;
296         jj = -1;
297         for (kk = 1 ; kk <= size ; kk++) {
298           if (size%kk==0) { /* a candidate */
299             PetscReal nactpe = (PetscReal)size/(PetscReal)kk, fact = nactpe/(PetscReal)new_size;
300             if (fact > 1.0) fact = 1./fact; /* keep fact < 1 */
301             if (fact > best_fact) {
302               best_fact = fact; jj = kk;
303             }
304           }
305         }
306         if (jj != -1) rfactor = jj;
307         else rfactor = 1; /* does this happen .. a prime */
308       }
309       new_size = size/rfactor;
310 
311       if (new_size==nactive) {
312         *a_Amat_crs = Cmat; /* output - no repartitioning or reduction, bail out because nested here */
313         ierr        = PetscFree(counts);CHKERRQ(ierr);
314         if (pc_gamg->verbose>0) {
315           PetscPrintf(wcomm,"\t[%d]%s aggregate processors noop: new_size=%d, neq(loc)=%d\n",rank,__FUNCT__,new_size,ncrs_eq);
316         }
317         PetscFunctionReturn(0);
318       }
319 
320       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s number of equations (loc) %d with simple aggregation\n",rank,__FUNCT__,ncrs_eq);
321       targetPE = rank/rfactor;
322       ierr     = ISCreateStride(wcomm, ncrs_eq, targetPE, 0, &is_eq_newproc);CHKERRQ(ierr);
323 
324       if (stokes) {
325         ierr = ISCreateStride(wcomm, ncrs_prim*cr_bs, targetPE, 0, &is_eq_newproc_prim);CHKERRQ(ierr);
326       }
327     } /* end simple 'is_eq_newproc' */
328 
329     /*
330      Create an index set from the is_eq_newproc index set to indicate the mapping TO
331      */
332     ierr = ISPartitioningToNumbering(is_eq_newproc, &is_eq_num);CHKERRQ(ierr);
333     if (stokes) {
334       ierr = ISPartitioningToNumbering(is_eq_newproc_prim, &is_eq_num_prim);CHKERRQ(ierr);
335     } else is_eq_num_prim = is_eq_num;
336     /*
337       Determine how many equations/vertices are assigned to each processor
338      */
339     ierr        = ISPartitioningCount(is_eq_newproc, size, counts);CHKERRQ(ierr);
340     ncrs_eq_new = counts[rank];
341     ierr        = ISDestroy(&is_eq_newproc);CHKERRQ(ierr);
342     if (stokes) {
343       ierr          = ISPartitioningCount(is_eq_newproc_prim, size, counts);CHKERRQ(ierr);
344       ierr          = ISDestroy(&is_eq_newproc_prim);CHKERRQ(ierr);
345       ncrs_prim_new = counts[rank]/cr_bs; /* nodes */
346     } else ncrs_prim_new = ncrs_eq_new/cr_bs; /* eqs */
347 
348     ierr = PetscFree(counts);CHKERRQ(ierr);
349 #if defined PETSC_GAMG_USE_LOG
350     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET12],0,0,0,0);CHKERRQ(ierr);
351 #endif
352 
353     /* move data (for primal equations only) */
354     /* Create a vector to contain the newly ordered element information */
355     ierr = VecCreate(wcomm, &dest_crd);CHKERRQ(ierr);
356     ierr = VecSetSizes(dest_crd, node_data_sz*ncrs_prim_new, PETSC_DECIDE);CHKERRQ(ierr);
357     ierr = VecSetFromOptions(dest_crd);CHKERRQ(ierr); /* this is needed! */
358     /*
359      There are 'ndata_rows*ndata_cols' data items per node, (one can think of the vectors of having
360      a block size of ...).  Note, ISs are expanded into equation space by 'cr_bs'.
361      */
362     ierr = PetscMalloc((ncrs_prim*node_data_sz)*sizeof(PetscInt), &tidx);CHKERRQ(ierr);
363     ierr = ISGetIndices(is_eq_num_prim, &idx);CHKERRQ(ierr);
364     for (ii=0,jj=0; ii<ncrs_prim; ii++) {
365       PetscInt id = idx[ii*cr_bs]/cr_bs; /* get node back */
366       for (kk=0; kk<node_data_sz; kk++, jj++) tidx[jj] = id*node_data_sz + kk;
367     }
368     ierr = ISRestoreIndices(is_eq_num_prim, &idx);CHKERRQ(ierr);
369     ierr = ISCreateGeneral(wcomm, node_data_sz*ncrs_prim, tidx, PETSC_COPY_VALUES, &isscat);CHKERRQ(ierr);
370     ierr = PetscFree(tidx);CHKERRQ(ierr);
371     /*
372      Create a vector to contain the original vertex information for each element
373      */
374     ierr = VecCreateSeq(PETSC_COMM_SELF, node_data_sz*ncrs_prim, &src_crd);CHKERRQ(ierr);
375     for (jj=0; jj<ndata_cols; jj++) {
376       const PetscInt stride0=ncrs_prim*pc_gamg->data_cell_rows;
377       for (ii=0; ii<ncrs_prim; ii++) {
378         for (kk=0; kk<ndata_rows; kk++) {
379           PetscInt    ix = ii*ndata_rows + kk + jj*stride0, jx = ii*node_data_sz + kk*ndata_cols + jj;
380           PetscScalar tt = (PetscScalar)pc_gamg->data[ix];
381           ierr = VecSetValues(src_crd, 1, &jx, &tt, INSERT_VALUES);CHKERRQ(ierr);
382         }
383       }
384     }
385     ierr = VecAssemblyBegin(src_crd);CHKERRQ(ierr);
386     ierr = VecAssemblyEnd(src_crd);CHKERRQ(ierr);
387     /*
388       Scatter the element vertex information (still in the original vertex ordering)
389       to the correct processor
390     */
391     ierr = VecScatterCreate(src_crd, NULL, dest_crd, isscat, &vecscat);CHKERRQ(ierr);
392     ierr = ISDestroy(&isscat);CHKERRQ(ierr);
393     ierr = VecScatterBegin(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
394     ierr = VecScatterEnd(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
395     ierr = VecScatterDestroy(&vecscat);CHKERRQ(ierr);
396     ierr = VecDestroy(&src_crd);CHKERRQ(ierr);
397     /*
398       Put the element vertex data into a new allocation of the gdata->ele
399     */
400     ierr = PetscFree(pc_gamg->data);CHKERRQ(ierr);
401     ierr = PetscMalloc(node_data_sz*ncrs_prim_new*sizeof(PetscReal), &pc_gamg->data);CHKERRQ(ierr);
402 
403     pc_gamg->data_sz = node_data_sz*ncrs_prim_new;
404     strideNew        = ncrs_prim_new*ndata_rows;
405 
406     ierr = VecGetArray(dest_crd, &array);CHKERRQ(ierr);
407     for (jj=0; jj<ndata_cols; jj++) {
408       for (ii=0; ii<ncrs_prim_new; ii++) {
409         for (kk=0; kk<ndata_rows; kk++) {
410           PetscInt ix = ii*ndata_rows + kk + jj*strideNew, jx = ii*node_data_sz + kk*ndata_cols + jj;
411           pc_gamg->data[ix] = PetscRealPart(array[jx]);
412         }
413       }
414     }
415     ierr = VecRestoreArray(dest_crd, &array);CHKERRQ(ierr);
416     ierr = VecDestroy(&dest_crd);CHKERRQ(ierr);
417 
418     /* move A and P (columns) with new layout */
419 #if defined PETSC_GAMG_USE_LOG
420     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
421 #endif
422 
423     /*
424       Invert for MatGetSubMatrix
425     */
426     ierr = ISInvertPermutation(is_eq_num, ncrs_eq_new, &new_eq_indices);CHKERRQ(ierr);
427     ierr = ISSort(new_eq_indices);CHKERRQ(ierr); /* is this needed? */
428     ierr = ISSetBlockSize(new_eq_indices, cr_bs);CHKERRQ(ierr);
429     if (is_eq_num != is_eq_num_prim) {
430       ierr = ISDestroy(&is_eq_num_prim);CHKERRQ(ierr); /* could be same as 'is_eq_num' */
431     }
432     ierr = ISDestroy(&is_eq_num);CHKERRQ(ierr);
433 #if defined PETSC_GAMG_USE_LOG
434     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
435     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
436 #endif
437     /* 'a_Amat_crs' output */
438     {
439       Mat mat;
440       ierr        = MatGetSubMatrix(Cmat, new_eq_indices, new_eq_indices, MAT_INITIAL_MATRIX, &mat);CHKERRQ(ierr);
441       *a_Amat_crs = mat;
442 
443       if (!PETSC_TRUE) {
444         PetscInt cbs, rbs;
445         ierr = MatGetBlockSizes(Cmat, &rbs, &cbs);CHKERRQ(ierr);
446         ierr = PetscPrintf(MPI_COMM_SELF,"[%d]%s Old Mat rbs=%d cbs=%d\n",rank,__FUNCT__,rbs,cbs);CHKERRQ(ierr);
447         ierr = MatGetBlockSizes(mat, &rbs, &cbs);CHKERRQ(ierr);
448         ierr = PetscPrintf(MPI_COMM_SELF,"[%d]%s New Mat rbs=%d cbs=%d cr_bs=%d\n",rank,__FUNCT__,rbs,cbs,cr_bs);CHKERRQ(ierr);
449       }
450     }
451     ierr = MatDestroy(&Cmat);CHKERRQ(ierr);
452 
453 #if defined PETSC_GAMG_USE_LOG
454     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
455 #endif
456     /* prolongator */
457     {
458       IS       findices;
459       PetscInt Istart,Iend;
460       Mat      Pnew;
461       ierr = MatGetOwnershipRange(Pold, &Istart, &Iend);CHKERRQ(ierr);
462 #if defined PETSC_GAMG_USE_LOG
463       ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
464 #endif
465       ierr = ISCreateStride(wcomm,Iend-Istart,Istart,1,&findices);CHKERRQ(ierr);
466       ierr = ISSetBlockSize(findices,f_bs);CHKERRQ(ierr);
467       ierr = MatGetSubMatrix(Pold, findices, new_eq_indices, MAT_INITIAL_MATRIX, &Pnew);CHKERRQ(ierr);
468       ierr = ISDestroy(&findices);CHKERRQ(ierr);
469 
470       if (!PETSC_TRUE) {
471         PetscInt cbs, rbs;
472         ierr = MatGetBlockSizes(Pold, &rbs, &cbs);CHKERRQ(ierr);
473         ierr = PetscPrintf(MPI_COMM_SELF,"[%d]%s Pold rbs=%d cbs=%d\n",rank,__FUNCT__,rbs,cbs);CHKERRQ(ierr);
474         ierr = MatGetBlockSizes(Pnew, &rbs, &cbs);CHKERRQ(ierr);
475         ierr = PetscPrintf(MPI_COMM_SELF,"[%d]%s Pnew rbs=%d cbs=%d\n",rank,__FUNCT__,rbs,cbs);CHKERRQ(ierr);
476       }
477 #if defined PETSC_GAMG_USE_LOG
478       ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
479 #endif
480       ierr = MatDestroy(a_P_inout);CHKERRQ(ierr);
481 
482       /* output - repartitioned */
483       *a_P_inout = Pnew;
484     }
485     ierr = ISDestroy(&new_eq_indices);CHKERRQ(ierr);
486 
487     *a_nactive_proc = new_size; /* output */
488   }
489 
490   /* outout matrix data */
491   if (!PETSC_TRUE) {
492     PetscViewer viewer; char fname[32]; static int llev=0; Cmat = *a_Amat_crs;
493     if (llev==0) {
494       sprintf(fname,"Cmat_%d.m",llev++);
495       PetscViewerASCIIOpen(wcomm,fname,&viewer);
496       ierr = PetscViewerSetFormat(viewer, PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
497       ierr = MatView(Amat_fine, viewer);CHKERRQ(ierr);
498       ierr = PetscViewerDestroy(&viewer);
499     }
500     sprintf(fname,"Cmat_%d.m",llev++);
501     PetscViewerASCIIOpen(wcomm,fname,&viewer);
502     ierr = PetscViewerSetFormat(viewer, PETSC_VIEWER_ASCII_MATLAB);CHKERRQ(ierr);
503     ierr = MatView(Cmat, viewer);CHKERRQ(ierr);
504     ierr = PetscViewerDestroy(&viewer);
505   }
506   PetscFunctionReturn(0);
507 }
508 
509 /* -------------------------------------------------------------------------- */
510 /*
511    PCSetUp_GAMG - Prepares for the use of the GAMG preconditioner
512                     by setting data structures and options.
513 
514    Input Parameter:
515 .  pc - the preconditioner context
516 
517    Application Interface Routine: PCSetUp()
518 
519    Notes:
520    The interface routine PCSetUp() is not usually called directly by
521    the user, but instead is called by PCApply() if necessary.
522 */
523 #undef __FUNCT__
524 #define __FUNCT__ "PCSetUp_GAMG"
525 PetscErrorCode PCSetUp_GAMG(PC pc)
526 {
527   PetscErrorCode ierr;
528   PC_MG          *mg      = (PC_MG*)pc->data;
529   PC_GAMG        *pc_gamg = (PC_GAMG*)mg->innerctx;
530   Mat            Pmat     = pc->pmat;
531   PetscInt       fine_level,level,level1,bs,M,qq,lidx,nASMBlocksArr[GAMG_MAXLEVELS];
532   MPI_Comm       wcomm = ((PetscObject)pc)->comm;
533   PetscMPIInt    rank,size,nactivepe;
534   Mat            Aarr[GAMG_MAXLEVELS],Parr[GAMG_MAXLEVELS];
535   PetscReal      emaxs[GAMG_MAXLEVELS];
536   IS             *ASMLocalIDsArr[GAMG_MAXLEVELS];
537   GAMGKKTMat     kktMatsArr[GAMG_MAXLEVELS];
538   PetscLogDouble nnz0=0.,nnztot=0.;
539   MatInfo        info;
540   PetscBool      stokes = PETSC_FALSE, redo_mesh_setup = (PetscBool)(!pc_gamg->reuse_prol);
541 
542   PetscFunctionBegin;
543   ierr = MPI_Comm_rank(wcomm,&rank);CHKERRQ(ierr);
544   ierr = MPI_Comm_size(wcomm,&size);CHKERRQ(ierr);
545 
546   if (pc_gamg->verbose>2) PetscPrintf(wcomm,"[%d]%s pc_gamg->setup_count=%d pc->setupcalled=%d\n",rank,__FUNCT__,pc_gamg->setup_count,pc->setupcalled);
547 
548   if (pc_gamg->setup_count++ > 0) {
549     if (redo_mesh_setup) {
550       /* reset everything */
551       ierr            = PCReset_MG(pc);CHKERRQ(ierr);
552       pc->setupcalled = 0;
553     } else {
554       PC_MG_Levels **mglevels = mg->levels;
555       /* just do Galerkin grids */
556       Mat B,dA,dB;
557       assert(pc->setupcalled);
558 
559       if (pc_gamg->Nlevels > 1) {
560         /* currently only handle case where mat and pmat are the same on coarser levels */
561         ierr = KSPGetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,&dA,&dB,NULL);CHKERRQ(ierr);
562         /* (re)set to get dirty flag */
563         ierr = KSPSetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,dA,dB,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
564 
565         for (level=pc_gamg->Nlevels-2; level>-1; level--) {
566           /* the first time through the matrix structure has changed from repartitioning */
567           if (pc_gamg->setup_count==2 /*&& (pc_gamg->repart || level==0)*/) {
568             ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_INITIAL_MATRIX,1.0,&B);CHKERRQ(ierr);
569             ierr = MatDestroy(&mglevels[level]->A);CHKERRQ(ierr);
570 
571             mglevels[level]->A = B;
572           } else {
573             ierr = KSPGetOperators(mglevels[level]->smoothd,NULL,&B,NULL);CHKERRQ(ierr);
574             ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_REUSE_MATRIX,1.0,&B);CHKERRQ(ierr);
575           }
576           ierr = KSPSetOperators(mglevels[level]->smoothd,B,B,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
577           dB   = B;
578         }
579       }
580 
581       ierr = PCSetUp_MG(pc);CHKERRQ(ierr);
582 
583       /* PCSetUp_MG seems to insists on setting this to GMRES */
584       ierr = KSPSetType(mglevels[0]->smoothd, KSPPREONLY);CHKERRQ(ierr);
585       PetscFunctionReturn(0);
586     }
587   }
588 
589   ierr = PetscOptionsGetBool(((PetscObject)pc)->prefix,"-pc_fieldsplit_detect_saddle_point",&stokes,NULL);CHKERRQ(ierr);
590 
591   ierr = GAMGKKTMatCreate(Pmat, stokes, &kktMatsArr[0]);CHKERRQ(ierr);
592 
593   if (!pc_gamg->data) {
594     if (pc_gamg->orig_data) {
595       ierr = MatGetBlockSize(Pmat, &bs);CHKERRQ(ierr);
596       ierr = MatGetLocalSize(Pmat, &qq, NULL);CHKERRQ(ierr);
597 
598       pc_gamg->data_sz        = (qq/bs)*pc_gamg->orig_data_cell_rows*pc_gamg->orig_data_cell_cols;
599       pc_gamg->data_cell_rows = pc_gamg->orig_data_cell_rows;
600       pc_gamg->data_cell_cols = pc_gamg->orig_data_cell_cols;
601 
602       ierr = PetscMalloc(pc_gamg->data_sz*sizeof(PetscReal), &pc_gamg->data);CHKERRQ(ierr);
603       for (qq=0; qq<pc_gamg->data_sz; qq++) pc_gamg->data[qq] = pc_gamg->orig_data[qq];
604     } else {
605       if (!pc_gamg->createdefaultdata) SETERRQ(wcomm,PETSC_ERR_PLIB,"'createdefaultdata' not set(?) need to support NULL data");
606       if (stokes) SETERRQ(wcomm,PETSC_ERR_PLIB,"Need data (eg, PCSetCoordinates) for Stokes problems");
607       ierr = pc_gamg->createdefaultdata(pc, kktMatsArr[0].A11);CHKERRQ(ierr);
608     }
609   }
610 
611   /* cache original data for reuse */
612   if (!pc_gamg->orig_data && redo_mesh_setup) {
613     ierr = PetscMalloc(pc_gamg->data_sz*sizeof(PetscReal), &pc_gamg->orig_data);CHKERRQ(ierr);
614     for (qq=0; qq<pc_gamg->data_sz; qq++) pc_gamg->orig_data[qq] = pc_gamg->data[qq];
615     pc_gamg->orig_data_cell_rows = pc_gamg->data_cell_rows;
616     pc_gamg->orig_data_cell_cols = pc_gamg->data_cell_cols;
617   }
618 
619   /* get basic dims */
620   if (stokes) bs = pc_gamg->data_cell_rows; /* this is agg-mg specific */
621   else {
622     ierr = MatGetBlockSize(Pmat, &bs);CHKERRQ(ierr);
623   }
624 
625   ierr = MatGetSize(Pmat, &M, &qq);CHKERRQ(ierr);
626   if (pc_gamg->verbose) {
627     PetscInt NN = M;
628     if (pc_gamg->verbose==1) {
629       ierr =  MatGetInfo(Pmat,MAT_LOCAL,&info);CHKERRQ(ierr);
630       ierr = MatGetLocalSize(Pmat, &NN, &qq);CHKERRQ(ierr);
631     } else {
632       ierr = MatGetInfo(Pmat,MAT_GLOBAL_SUM,&info);CHKERRQ(ierr);
633     }
634     nnz0   = info.nz_used;
635     nnztot = info.nz_used;
636     ierr   = PetscPrintf(wcomm,"\t[%d]%s level %d N=%d, n data rows=%d, n data cols=%d, nnz/row (ave)=%d, np=%d\n",
637                          rank,__FUNCT__,0,M,pc_gamg->data_cell_rows,pc_gamg->data_cell_cols,
638                          (int)(nnz0/(PetscReal)NN),size);CHKERRQ(ierr);
639   }
640 
641   /* Get A_i and R_i */
642   for (level=0, Aarr[0]=Pmat, nactivepe = size; /* hard wired stopping logic */
643        level < (pc_gamg->Nlevels-1) && (level==0 || M>pc_gamg->coarse_eq_limit);  /* && (size==1 || nactivepe>1); */
644        level++) {
645     level1 = level + 1;
646 #if defined PETSC_GAMG_USE_LOG
647     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET1],0,0,0,0);CHKERRQ(ierr);
648 #if (defined GAMG_STAGES)
649     ierr = PetscLogStagePush(gamg_stages[level]);CHKERRQ(ierr);
650 #endif
651 #endif
652     /* deal with Stokes, get sub matrices */
653     if (level > 0) {
654       ierr = GAMGKKTMatCreate(Aarr[level], stokes, &kktMatsArr[level]);CHKERRQ(ierr);
655     }
656     { /* construct prolongator */
657       Mat              Gmat;
658       PetscCoarsenData *agg_lists;
659       Mat              Prol11,Prol22;
660 
661       ierr = pc_gamg->graph(pc,kktMatsArr[level].A11, &Gmat);CHKERRQ(ierr);
662       ierr = pc_gamg->coarsen(pc, &Gmat, &agg_lists);CHKERRQ(ierr);
663       ierr = pc_gamg->prolongator(pc, kktMatsArr[level].A11, Gmat, agg_lists, &Prol11);CHKERRQ(ierr);
664 
665       /* could have failed to create new level */
666       if (Prol11) {
667         /* get new block size of coarse matrices */
668         ierr = MatGetBlockSizes(Prol11, NULL, &bs);CHKERRQ(ierr);
669 
670         if (stokes) {
671           if (!pc_gamg->formkktprol) SETERRQ(wcomm,PETSC_ERR_USER,"Stokes not supportd by AMG method.");
672           /* R A12 == (T = A21 P)';  G = T' T; coarsen G; form plain agg with G */
673           ierr = pc_gamg->formkktprol(pc, Prol11, kktMatsArr[level].A21, &Prol22);CHKERRQ(ierr);
674         }
675 
676         if (pc_gamg->optprol) {
677           /* smooth */
678           ierr = pc_gamg->optprol(pc, kktMatsArr[level].A11, &Prol11);CHKERRQ(ierr);
679         }
680 
681         if (stokes) {
682           IS  is_row[2];
683           Mat a[4];
684 
685           is_row[0] = kktMatsArr[level].prim_is; is_row[1] = kktMatsArr[level].constr_is;
686           a[0]      = Prol11; a[1] = NULL; a[2] = NULL; a[3] = Prol22;
687           ierr      = MatCreateNest(wcomm,2,is_row, 2, is_row, a, &Parr[level1]);CHKERRQ(ierr);
688         } else Parr[level1] = Prol11;
689       } else Parr[level1] = NULL;
690 
691       if (pc_gamg->use_aggs_in_gasm) {
692         ierr = PetscCDGetASMBlocks(agg_lists, bs, &nASMBlocksArr[level], &ASMLocalIDsArr[level]);CHKERRQ(ierr);
693       }
694 
695       ierr = MatDestroy(&Gmat);CHKERRQ(ierr);
696       ierr = PetscCDDestroy(agg_lists);CHKERRQ(ierr);
697     } /* construct prolongator scope */
698 #if defined PETSC_GAMG_USE_LOG
699     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET1],0,0,0,0);CHKERRQ(ierr);
700 #endif
701     /* cache eigen estimate */
702     if (pc_gamg->emax_id != -1) {
703       PetscBool flag;
704       ierr = PetscObjectComposedDataGetReal((PetscObject)kktMatsArr[level].A11, pc_gamg->emax_id, emaxs[level], flag);CHKERRQ(ierr);
705       if (!flag) emaxs[level] = -1.;
706     } else emaxs[level] = -1.;
707     if (level==0) Aarr[0] = Pmat; /* use Pmat for finest level setup */
708     if (!Parr[level1]) {
709       if (pc_gamg->verbose) {
710         ierr =  PetscPrintf(wcomm,"\t[%d]%s stop gridding, level %d\n",rank,__FUNCT__,level);CHKERRQ(ierr);
711       }
712       break;
713     }
714 #if defined PETSC_GAMG_USE_LOG
715     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
716 #endif
717 
718     ierr = createLevel(pc, Aarr[level], bs, (PetscBool)(level==pc_gamg->Nlevels-2),
719                        stokes, &Parr[level1], &Aarr[level1], &nactivepe);CHKERRQ(ierr);
720 
721 #if defined PETSC_GAMG_USE_LOG
722     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
723 #endif
724     ierr = MatGetSize(Aarr[level1], &M, &qq);CHKERRQ(ierr);
725 
726     if (pc_gamg->verbose > 0) {
727       PetscInt NN = M;
728       if (pc_gamg->verbose==1) {
729         ierr = MatGetInfo(Aarr[level1],MAT_LOCAL,&info);CHKERRQ(ierr);
730         ierr = MatGetLocalSize(Aarr[level1], &NN, &qq);CHKERRQ(ierr);
731       } else {
732         ierr = MatGetInfo(Aarr[level1], MAT_GLOBAL_SUM, &info);CHKERRQ(ierr);
733       }
734 
735       nnztot += info.nz_used;
736       ierr    = PetscPrintf(wcomm,"\t\t[%d]%s %d) N=%d, n data cols=%d, nnz/row (ave)=%d, %d active pes\n",
737                             rank,__FUNCT__,(int)level1,M,pc_gamg->data_cell_cols,
738                             (int)(info.nz_used/(PetscReal)NN), nactivepe);CHKERRQ(ierr);
739     }
740 
741     /* stop if one node -- could pull back for singular problems */
742     if (M/pc_gamg->data_cell_cols < 2) {
743       level++;
744       break;
745     }
746 #if (defined PETSC_GAMG_USE_LOG && defined GAMG_STAGES)
747     ierr = PetscLogStagePop();CHKERRQ(ierr);
748 #endif
749   } /* levels */
750 
751   if (pc_gamg->data) {
752     ierr          = PetscFree(pc_gamg->data);CHKERRQ(ierr);
753     pc_gamg->data = NULL;
754   }
755 
756   if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s %d levels, grid complexity = %g\n",0,__FUNCT__,level+1,nnztot/nnz0);
757   pc_gamg->Nlevels = level + 1;
758   fine_level       = level;
759   ierr             = PCMGSetLevels(pc,pc_gamg->Nlevels,NULL);CHKERRQ(ierr);
760 
761   /* simple setup */
762   if (!PETSC_TRUE) {
763     PC_MG_Levels **mglevels = mg->levels;
764     for (lidx=0,level=pc_gamg->Nlevels-1;
765          lidx<fine_level;
766          lidx++, level--) {
767       ierr = PCMGSetInterpolation(pc, lidx+1, Parr[level]);CHKERRQ(ierr);
768       ierr = KSPSetOperators(mglevels[lidx]->smoothd, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN);CHKERRQ(ierr);
769       ierr = MatDestroy(&Parr[level]);CHKERRQ(ierr);
770       ierr = MatDestroy(&Aarr[level]);CHKERRQ(ierr);
771     }
772     ierr = KSPSetOperators(mglevels[fine_level]->smoothd, Aarr[0], Aarr[0], SAME_NONZERO_PATTERN);CHKERRQ(ierr);
773 
774     ierr = PCSetUp_MG(pc);CHKERRQ(ierr);
775   } else if (pc_gamg->Nlevels > 1) { /* don't setup MG if one level */
776     /* set default smoothers & set operators */
777     for (lidx = 1, level = pc_gamg->Nlevels-2;
778          lidx <= fine_level;
779          lidx++, level--) {
780       KSP smoother;
781       PC  subpc;
782 
783       ierr = PCMGGetSmoother(pc, lidx, &smoother);CHKERRQ(ierr);
784       ierr = KSPGetPC(smoother, &subpc);CHKERRQ(ierr);
785 
786       ierr = KSPSetNormType(smoother, KSP_NORM_NONE);CHKERRQ(ierr);
787       /* set ops */
788       ierr = KSPSetOperators(smoother, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN);CHKERRQ(ierr);
789       ierr = PCMGSetInterpolation(pc, lidx, Parr[level+1]);CHKERRQ(ierr);
790 
791       /* create field split PC, get subsmoother */
792       if (stokes) {
793         KSP      *ksps;
794         PetscInt nn;
795         ierr     = PCFieldSplitSetIS(subpc,"0",kktMatsArr[level].prim_is);CHKERRQ(ierr);
796         ierr     = PCFieldSplitSetIS(subpc,"1",kktMatsArr[level].constr_is);CHKERRQ(ierr);
797         ierr     = PCFieldSplitGetSubKSP(subpc,&nn,&ksps);CHKERRQ(ierr);
798         smoother = ksps[0];
799         ierr     = KSPGetPC(smoother, &subpc);CHKERRQ(ierr);
800         ierr     = PetscFree(ksps);CHKERRQ(ierr);
801       }
802       ierr = GAMGKKTMatDestroy(&kktMatsArr[level]);CHKERRQ(ierr);
803 
804       /* set defaults */
805       ierr = KSPSetType(smoother, KSPCHEBYSHEV);CHKERRQ(ierr);
806 
807       /* override defaults and command line args (!) */
808       if (pc_gamg->use_aggs_in_gasm) {
809         PetscInt sz;
810         IS       *is;
811 
812         sz   = nASMBlocksArr[level];
813         is   = ASMLocalIDsArr[level];
814         ierr = PCSetType(subpc, PCGASM);CHKERRQ(ierr);
815         if (sz==0) {
816           IS       is;
817           PetscInt my0,kk;
818           ierr = MatGetOwnershipRange(Aarr[level], &my0, &kk);CHKERRQ(ierr);
819           ierr = ISCreateGeneral(PETSC_COMM_SELF, 1, &my0, PETSC_COPY_VALUES, &is);CHKERRQ(ierr);
820           ierr = PCGASMSetSubdomains(subpc, 1, &is, NULL);CHKERRQ(ierr);
821           ierr = ISDestroy(&is);CHKERRQ(ierr);
822         } else {
823           PetscInt kk;
824           ierr = PCGASMSetSubdomains(subpc, sz, is, NULL);CHKERRQ(ierr);
825           for (kk=0; kk<sz; kk++) {
826             ierr = ISDestroy(&is[kk]);CHKERRQ(ierr);
827           }
828           ierr = PetscFree(is);CHKERRQ(ierr);
829         }
830         ierr = PCGASMSetOverlap(subpc, 0);CHKERRQ(ierr);
831 
832         ASMLocalIDsArr[level] = NULL;
833         nASMBlocksArr[level]  = 0;
834         ierr                  = PCGASMSetType(subpc, PC_GASM_BASIC);CHKERRQ(ierr);
835       } else {
836         ierr = PCSetType(subpc, PCJACOBI);CHKERRQ(ierr);
837       }
838     }
839     {
840       /* coarse grid */
841       KSP smoother,*k2; PC subpc,pc2; PetscInt ii,first;
842       Mat Lmat = Aarr[(level=pc_gamg->Nlevels-1)]; lidx = 0;
843       ierr = PCMGGetSmoother(pc, lidx, &smoother);CHKERRQ(ierr);
844       ierr = KSPSetOperators(smoother, Lmat, Lmat, SAME_NONZERO_PATTERN);CHKERRQ(ierr);
845       ierr = KSPSetNormType(smoother, KSP_NORM_NONE);CHKERRQ(ierr);
846       ierr = KSPGetPC(smoother, &subpc);CHKERRQ(ierr);
847       ierr = PCSetType(subpc, PCBJACOBI);CHKERRQ(ierr);
848       ierr = PCSetUp(subpc);CHKERRQ(ierr);
849       ierr = PCBJacobiGetSubKSP(subpc,&ii,&first,&k2);CHKERRQ(ierr);      assert(ii==1);
850       ierr = KSPGetPC(k2[0],&pc2);CHKERRQ(ierr);
851       ierr = PCSetType(pc2, PCLU);CHKERRQ(ierr);
852       ierr = PCFactorSetShiftType(pc2,MAT_SHIFT_INBLOCKS);CHKERRQ(ierr);
853     }
854 
855     /* should be called in PCSetFromOptions_GAMG(), but cannot be called prior to PCMGSetLevels() */
856     ierr = PetscObjectOptionsBegin((PetscObject)pc);CHKERRQ(ierr);
857     ierr = PCSetFromOptions_MG(pc);CHKERRQ(ierr);
858     ierr = PetscOptionsEnd();CHKERRQ(ierr);
859     if (mg->galerkin != 2) SETERRQ(wcomm,PETSC_ERR_USER,"GAMG does Galerkin manually so the -pc_mg_galerkin option must not be used.");
860 
861     /* create cheby smoothers */
862     for (lidx = 1, level = pc_gamg->Nlevels-2;
863          lidx <= fine_level;
864          lidx++, level--) {
865       KSP       smoother;
866       PetscBool flag;
867       PC        subpc;
868 
869       ierr = PCMGGetSmoother(pc, lidx, &smoother);CHKERRQ(ierr);
870       ierr = KSPGetPC(smoother, &subpc);CHKERRQ(ierr);
871 
872       /* create field split PC, get subsmoother */
873       if (stokes) {
874         KSP      *ksps;
875         PetscInt nn;
876         ierr     = PCFieldSplitGetSubKSP(subpc,&nn,&ksps);CHKERRQ(ierr);
877         smoother = ksps[0];
878         ierr     = KSPGetPC(smoother, &subpc);CHKERRQ(ierr);
879         ierr     = PetscFree(ksps);CHKERRQ(ierr);
880       }
881 
882       /* do my own cheby */
883       ierr = PetscObjectTypeCompare((PetscObject)smoother, KSPCHEBYSHEV, &flag);CHKERRQ(ierr);
884       if (flag) {
885         PetscReal emax, emin;
886         ierr = PetscObjectTypeCompare((PetscObject)subpc, PCJACOBI, &flag);CHKERRQ(ierr);
887         if (flag && emaxs[level] > 0.0) emax=emaxs[level]; /* eigen estimate only for diagnal PC */
888         else { /* eigen estimate 'emax' */
889           KSP eksp;
890           Mat Lmat = Aarr[level];
891           Vec bb, xx;
892 
893           ierr = MatGetVecs(Lmat, &bb, 0);CHKERRQ(ierr);
894           ierr = MatGetVecs(Lmat, &xx, 0);CHKERRQ(ierr);
895           {
896             PetscRandom rctx;
897             ierr = PetscRandomCreate(wcomm,&rctx);CHKERRQ(ierr);
898             ierr = PetscRandomSetFromOptions(rctx);CHKERRQ(ierr);
899             ierr = VecSetRandom(bb,rctx);CHKERRQ(ierr);
900             ierr = PetscRandomDestroy(&rctx);CHKERRQ(ierr);
901           }
902 
903           /* zeroing out BC rows -- needed for crazy matrices */
904           {
905             PetscInt    Istart,Iend,ncols,jj,Ii;
906             PetscScalar zero = 0.0;
907             ierr = MatGetOwnershipRange(Lmat, &Istart, &Iend);CHKERRQ(ierr);
908             for (Ii = Istart, jj = 0; Ii < Iend; Ii++, jj++) {
909               ierr = MatGetRow(Lmat,Ii,&ncols,0,0);CHKERRQ(ierr);
910               if (ncols <= 1) {
911                 ierr = VecSetValues(bb, 1, &Ii, &zero, INSERT_VALUES);CHKERRQ(ierr);
912               }
913               ierr = MatRestoreRow(Lmat,Ii,&ncols,0,0);CHKERRQ(ierr);
914             }
915             ierr = VecAssemblyBegin(bb);CHKERRQ(ierr);
916             ierr = VecAssemblyEnd(bb);CHKERRQ(ierr);
917           }
918 
919           ierr = KSPCreate(wcomm, &eksp);CHKERRQ(ierr);
920           ierr = KSPSetTolerances(eksp, PETSC_DEFAULT, PETSC_DEFAULT, PETSC_DEFAULT, 10);CHKERRQ(ierr);
921           ierr = KSPSetNormType(eksp, KSP_NORM_NONE);CHKERRQ(ierr);
922           ierr = KSPSetOptionsPrefix(eksp,((PetscObject)pc)->prefix);CHKERRQ(ierr);
923           ierr = KSPAppendOptionsPrefix(eksp, "gamg_est_");CHKERRQ(ierr);
924           ierr = KSPSetFromOptions(eksp);CHKERRQ(ierr);
925 
926           ierr = KSPSetInitialGuessNonzero(eksp, PETSC_FALSE);CHKERRQ(ierr);
927           ierr = KSPSetOperators(eksp, Lmat, Lmat, SAME_NONZERO_PATTERN);CHKERRQ(ierr);
928           ierr = KSPSetComputeSingularValues(eksp,PETSC_TRUE);CHKERRQ(ierr);
929 
930           /* set PC type to be same as smoother */
931           ierr = KSPSetPC(eksp, subpc);CHKERRQ(ierr);
932 
933           /* solve - keep stuff out of logging */
934           ierr = PetscLogEventDeactivate(KSP_Solve);CHKERRQ(ierr);
935           ierr = PetscLogEventDeactivate(PC_Apply);CHKERRQ(ierr);
936           ierr = KSPSolve(eksp, bb, xx);CHKERRQ(ierr);
937           ierr = PetscLogEventActivate(KSP_Solve);CHKERRQ(ierr);
938           ierr = PetscLogEventActivate(PC_Apply);CHKERRQ(ierr);
939 
940           ierr = KSPComputeExtremeSingularValues(eksp, &emax, &emin);CHKERRQ(ierr);
941 
942           ierr = VecDestroy(&xx);CHKERRQ(ierr);
943           ierr = VecDestroy(&bb);CHKERRQ(ierr);
944           ierr = KSPDestroy(&eksp);CHKERRQ(ierr);
945 
946           if (pc_gamg->verbose > 0) {
947             PetscInt N1, tt;
948             ierr = MatGetSize(Aarr[level], &N1, &tt);CHKERRQ(ierr);
949             PetscPrintf(wcomm,"\t\t\t%s PC setup max eigen=%e min=%e on level %d (N=%d)\n",__FUNCT__,emax,emin,lidx,N1);
950           }
951         }
952         {
953           PetscInt N1, N0;
954           ierr = MatGetSize(Aarr[level], &N1, NULL);CHKERRQ(ierr);
955           ierr = MatGetSize(Aarr[level+1], &N0, NULL);CHKERRQ(ierr);
956           /* heuristic - is this crap? */
957           /* emin = 1.*emax/((PetscReal)N1/(PetscReal)N0); */
958           emin  = emax * pc_gamg->eigtarget[0];
959           emax *= pc_gamg->eigtarget[1];
960         }
961         ierr = KSPChebyshevSetEigenvalues(smoother, emax, emin);CHKERRQ(ierr);
962       } /* setup checby flag */
963     } /* non-coarse levels */
964 
965     /* clean up */
966     for (level=1; level<pc_gamg->Nlevels; level++) {
967       ierr = MatDestroy(&Parr[level]);CHKERRQ(ierr);
968       ierr = MatDestroy(&Aarr[level]);CHKERRQ(ierr);
969     }
970 
971     ierr = PCSetUp_MG(pc);CHKERRQ(ierr);
972 
973     if (PETSC_TRUE) {
974       KSP smoother;  /* PCSetUp_MG seems to insists on setting this to GMRES on coarse grid */
975       ierr = PCMGGetSmoother(pc, 0, &smoother);CHKERRQ(ierr);
976       ierr = KSPSetType(smoother, KSPPREONLY);CHKERRQ(ierr);
977     }
978   } else {
979     KSP smoother;
980     if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s one level solver used (system is seen as DD). Using default solver.\n",rank,__FUNCT__);
981     ierr = PCMGGetSmoother(pc, 0, &smoother);CHKERRQ(ierr);
982     ierr = KSPSetOperators(smoother, Aarr[0], Aarr[0], SAME_NONZERO_PATTERN);CHKERRQ(ierr);
983     ierr = KSPSetType(smoother, KSPPREONLY);CHKERRQ(ierr);
984     ierr = PCSetUp_MG(pc);CHKERRQ(ierr);
985   }
986   PetscFunctionReturn(0);
987 }
988 
989 /* ------------------------------------------------------------------------- */
990 /*
991  PCDestroy_GAMG - Destroys the private context for the GAMG preconditioner
992    that was created with PCCreate_GAMG().
993 
994    Input Parameter:
995 .  pc - the preconditioner context
996 
997    Application Interface Routine: PCDestroy()
998 */
999 #undef __FUNCT__
1000 #define __FUNCT__ "PCDestroy_GAMG"
1001 PetscErrorCode PCDestroy_GAMG(PC pc)
1002 {
1003   PetscErrorCode ierr;
1004   PC_MG          *mg     = (PC_MG*)pc->data;
1005   PC_GAMG        *pc_gamg= (PC_GAMG*)mg->innerctx;
1006 
1007   PetscFunctionBegin;
1008   ierr = PCReset_GAMG(pc);CHKERRQ(ierr);
1009   ierr = PetscFree(pc_gamg);CHKERRQ(ierr);
1010   ierr = PCDestroy_MG(pc);CHKERRQ(ierr);
1011   PetscFunctionReturn(0);
1012 }
1013 
1014 
1015 #undef __FUNCT__
1016 #define __FUNCT__ "PCGAMGSetProcEqLim"
1017 /*@
1018    PCGAMGSetProcEqLim - Set number of equations to aim for on coarse grids via
1019    processor reduction.
1020 
1021    Not Collective on PC
1022 
1023    Input Parameters:
1024 .  pc - the preconditioner context
1025 
1026 
1027    Options Database Key:
1028 .  -pc_gamg_process_eq_limit
1029 
1030    Level: intermediate
1031 
1032    Concepts: Unstructured multrigrid preconditioner
1033 
1034 .seealso: ()
1035 @*/
1036 PetscErrorCode  PCGAMGSetProcEqLim(PC pc, PetscInt n)
1037 {
1038   PetscErrorCode ierr;
1039 
1040   PetscFunctionBegin;
1041   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1042   ierr = PetscTryMethod(pc,"PCGAMGSetProcEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1043   PetscFunctionReturn(0);
1044 }
1045 
1046 EXTERN_C_BEGIN
1047 #undef __FUNCT__
1048 #define __FUNCT__ "PCGAMGSetProcEqLim_GAMG"
1049 PetscErrorCode PCGAMGSetProcEqLim_GAMG(PC pc, PetscInt n)
1050 {
1051   PC_MG   *mg      = (PC_MG*)pc->data;
1052   PC_GAMG *pc_gamg = (PC_GAMG*)mg->innerctx;
1053 
1054   PetscFunctionBegin;
1055   if (n>0) pc_gamg->min_eq_proc = n;
1056   PetscFunctionReturn(0);
1057 }
1058 EXTERN_C_END
1059 
1060 #undef __FUNCT__
1061 #define __FUNCT__ "PCGAMGSetCoarseEqLim"
1062 /*@
1063    PCGAMGSetCoarseEqLim - Set max number of equations on coarse grids.
1064 
1065  Collective on PC
1066 
1067    Input Parameters:
1068 .  pc - the preconditioner context
1069 
1070 
1071    Options Database Key:
1072 .  -pc_gamg_coarse_eq_limit
1073 
1074    Level: intermediate
1075 
1076    Concepts: Unstructured multrigrid preconditioner
1077 
1078 .seealso: ()
1079  @*/
1080 PetscErrorCode PCGAMGSetCoarseEqLim(PC pc, PetscInt n)
1081 {
1082   PetscErrorCode ierr;
1083 
1084   PetscFunctionBegin;
1085   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1086   ierr = PetscTryMethod(pc,"PCGAMGSetCoarseEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1087   PetscFunctionReturn(0);
1088 }
1089 
1090 EXTERN_C_BEGIN
1091 #undef __FUNCT__
1092 #define __FUNCT__ "PCGAMGSetCoarseEqLim_GAMG"
1093 PetscErrorCode PCGAMGSetCoarseEqLim_GAMG(PC pc, PetscInt n)
1094 {
1095   PC_MG   *mg      = (PC_MG*)pc->data;
1096   PC_GAMG *pc_gamg = (PC_GAMG*)mg->innerctx;
1097 
1098   PetscFunctionBegin;
1099   if (n>0) pc_gamg->coarse_eq_limit = n;
1100   PetscFunctionReturn(0);
1101 }
1102 EXTERN_C_END
1103 
1104 #undef __FUNCT__
1105 #define __FUNCT__ "PCGAMGSetRepartitioning"
1106 /*@
1107    PCGAMGSetRepartitioning - Repartition the coarse grids
1108 
1109    Collective on PC
1110 
1111    Input Parameters:
1112 .  pc - the preconditioner context
1113 
1114 
1115    Options Database Key:
1116 .  -pc_gamg_repartition
1117 
1118    Level: intermediate
1119 
1120    Concepts: Unstructured multrigrid preconditioner
1121 
1122 .seealso: ()
1123 @*/
1124 PetscErrorCode PCGAMGSetRepartitioning(PC pc, PetscBool n)
1125 {
1126   PetscErrorCode ierr;
1127 
1128   PetscFunctionBegin;
1129   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1130   ierr = PetscTryMethod(pc,"PCGAMGSetRepartitioning_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
1131   PetscFunctionReturn(0);
1132 }
1133 
1134 EXTERN_C_BEGIN
1135 #undef __FUNCT__
1136 #define __FUNCT__ "PCGAMGSetRepartitioning_GAMG"
1137 PetscErrorCode PCGAMGSetRepartitioning_GAMG(PC pc, PetscBool n)
1138 {
1139   PC_MG   *mg      = (PC_MG*)pc->data;
1140   PC_GAMG *pc_gamg = (PC_GAMG*)mg->innerctx;
1141 
1142   PetscFunctionBegin;
1143   pc_gamg->repart = n;
1144   PetscFunctionReturn(0);
1145 }
1146 EXTERN_C_END
1147 
1148 #undef __FUNCT__
1149 #define __FUNCT__ "PCGAMGSetReuseProl"
1150 /*@
1151    PCGAMGSetReuseProl - Reuse prlongation
1152 
1153    Collective on PC
1154 
1155    Input Parameters:
1156 .  pc - the preconditioner context
1157 
1158 
1159    Options Database Key:
1160 .  -pc_gamg_reuse_interpolation
1161 
1162    Level: intermediate
1163 
1164    Concepts: Unstructured multrigrid preconditioner
1165 
1166 .seealso: ()
1167 @*/
1168 PetscErrorCode PCGAMGSetReuseProl(PC pc, PetscBool n)
1169 {
1170   PetscErrorCode ierr;
1171 
1172   PetscFunctionBegin;
1173   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1174   ierr = PetscTryMethod(pc,"PCGAMGSetReuseProl_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
1175   PetscFunctionReturn(0);
1176 }
1177 
1178 EXTERN_C_BEGIN
1179 #undef __FUNCT__
1180 #define __FUNCT__ "PCGAMGSetReuseProl_GAMG"
1181 PetscErrorCode PCGAMGSetReuseProl_GAMG(PC pc, PetscBool n)
1182 {
1183   PC_MG   *mg      = (PC_MG*)pc->data;
1184   PC_GAMG *pc_gamg = (PC_GAMG*)mg->innerctx;
1185 
1186   PetscFunctionBegin;
1187   pc_gamg->reuse_prol = n;
1188   PetscFunctionReturn(0);
1189 }
1190 EXTERN_C_END
1191 
1192 #undef __FUNCT__
1193 #define __FUNCT__ "PCGAMGSetUseASMAggs"
1194 /*@
1195    PCGAMGSetUseASMAggs -
1196 
1197    Collective on PC
1198 
1199    Input Parameters:
1200 .  pc - the preconditioner context
1201 
1202 
1203    Options Database Key:
1204 .  -pc_gamg_use_agg_gasm
1205 
1206    Level: intermediate
1207 
1208    Concepts: Unstructured multrigrid preconditioner
1209 
1210 .seealso: ()
1211 @*/
1212 PetscErrorCode PCGAMGSetUseASMAggs(PC pc, PetscBool n)
1213 {
1214   PetscErrorCode ierr;
1215 
1216   PetscFunctionBegin;
1217   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1218   ierr = PetscTryMethod(pc,"PCGAMGSetUseASMAggs_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
1219   PetscFunctionReturn(0);
1220 }
1221 
1222 EXTERN_C_BEGIN
1223 #undef __FUNCT__
1224 #define __FUNCT__ "PCGAMGSetUseASMAggs_GAMG"
1225 PetscErrorCode PCGAMGSetUseASMAggs_GAMG(PC pc, PetscBool n)
1226 {
1227   PC_MG   *mg      = (PC_MG*)pc->data;
1228   PC_GAMG *pc_gamg = (PC_GAMG*)mg->innerctx;
1229 
1230   PetscFunctionBegin;
1231   pc_gamg->use_aggs_in_gasm = n;
1232   PetscFunctionReturn(0);
1233 }
1234 EXTERN_C_END
1235 
1236 #undef __FUNCT__
1237 #define __FUNCT__ "PCGAMGSetNlevels"
1238 /*@
1239    PCGAMGSetNlevels -
1240 
1241    Not collective on PC
1242 
1243    Input Parameters:
1244 .  pc - the preconditioner context
1245 
1246 
1247    Options Database Key:
1248 .  -pc_mg_levels
1249 
1250    Level: intermediate
1251 
1252    Concepts: Unstructured multrigrid preconditioner
1253 
1254 .seealso: ()
1255 @*/
1256 PetscErrorCode PCGAMGSetNlevels(PC pc, PetscInt n)
1257 {
1258   PetscErrorCode ierr;
1259 
1260   PetscFunctionBegin;
1261   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1262   ierr = PetscTryMethod(pc,"PCGAMGSetNlevels_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1263   PetscFunctionReturn(0);
1264 }
1265 
1266 EXTERN_C_BEGIN
1267 #undef __FUNCT__
1268 #define __FUNCT__ "PCGAMGSetNlevels_GAMG"
1269 PetscErrorCode PCGAMGSetNlevels_GAMG(PC pc, PetscInt n)
1270 {
1271   PC_MG   *mg      = (PC_MG*)pc->data;
1272   PC_GAMG *pc_gamg = (PC_GAMG*)mg->innerctx;
1273 
1274   PetscFunctionBegin;
1275   pc_gamg->Nlevels = n;
1276   PetscFunctionReturn(0);
1277 }
1278 EXTERN_C_END
1279 
1280 #undef __FUNCT__
1281 #define __FUNCT__ "PCGAMGSetThreshold"
1282 /*@
1283    PCGAMGSetThreshold - Relative threshold to use for dropping edges in aggregation graph
1284 
1285    Not collective on PC
1286 
1287    Input Parameters:
1288 .  pc - the preconditioner context
1289 
1290 
1291    Options Database Key:
1292 .  -pc_gamg_threshold
1293 
1294    Level: intermediate
1295 
1296    Concepts: Unstructured multrigrid preconditioner
1297 
1298 .seealso: ()
1299 @*/
1300 PetscErrorCode PCGAMGSetThreshold(PC pc, PetscReal n)
1301 {
1302   PetscErrorCode ierr;
1303 
1304   PetscFunctionBegin;
1305   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1306   ierr = PetscTryMethod(pc,"PCGAMGSetThreshold_C",(PC,PetscReal),(pc,n));CHKERRQ(ierr);
1307   PetscFunctionReturn(0);
1308 }
1309 
1310 EXTERN_C_BEGIN
1311 #undef __FUNCT__
1312 #define __FUNCT__ "PCGAMGSetThreshold_GAMG"
1313 PetscErrorCode PCGAMGSetThreshold_GAMG(PC pc, PetscReal n)
1314 {
1315   PC_MG   *mg      = (PC_MG*)pc->data;
1316   PC_GAMG *pc_gamg = (PC_GAMG*)mg->innerctx;
1317 
1318   PetscFunctionBegin;
1319   pc_gamg->threshold = n;
1320   PetscFunctionReturn(0);
1321 }
1322 EXTERN_C_END
1323 
1324 #undef __FUNCT__
1325 #define __FUNCT__ "PCGAMGSetType"
1326 /*@
1327    PCGAMGSetType - Set solution method - calls sub create method
1328 
1329    Collective on PC
1330 
1331    Input Parameters:
1332 .  pc - the preconditioner context
1333 
1334 
1335    Options Database Key:
1336 .  -pc_gamg_type
1337 
1338    Level: intermediate
1339 
1340    Concepts: Unstructured multrigrid preconditioner
1341 
1342 .seealso: ()
1343 @*/
1344 PetscErrorCode PCGAMGSetType(PC pc, PCGAMGType type)
1345 {
1346   PetscErrorCode ierr;
1347 
1348   PetscFunctionBegin;
1349   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1350   ierr = PetscTryMethod(pc,"PCGAMGSetType_C",(PC,PCGAMGType),(pc,type));CHKERRQ(ierr);
1351   PetscFunctionReturn(0);
1352 }
1353 
1354 EXTERN_C_BEGIN
1355 #undef __FUNCT__
1356 #define __FUNCT__ "PCGAMGSetType_GAMG"
1357 PetscErrorCode PCGAMGSetType_GAMG(PC pc, PCGAMGType type)
1358 {
1359   PetscErrorCode ierr,(*r)(PC);
1360 
1361   PetscFunctionBegin;
1362   ierr = PetscFunctionListFind(((PetscObject)pc)->comm,GAMGList,type,PETSC_FALSE,(PetscVoidStarFunction)&r);CHKERRQ(ierr);
1363   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unknown GAMG type %s given",type);
1364   ierr = (*r)(pc);CHKERRQ(ierr);
1365   PetscFunctionReturn(0);
1366 }
1367 EXTERN_C_END
1368 
1369 #undef __FUNCT__
1370 #define __FUNCT__ "PCSetFromOptions_GAMG"
1371 PetscErrorCode PCSetFromOptions_GAMG(PC pc)
1372 {
1373   PetscErrorCode ierr;
1374   PC_MG          *mg      = (PC_MG*)pc->data;
1375   PC_GAMG        *pc_gamg = (PC_GAMG*)mg->innerctx;
1376   PetscBool      flag;
1377   PetscInt       two   = 2;
1378   MPI_Comm       wcomm = ((PetscObject)pc)->comm;
1379 
1380   PetscFunctionBegin;
1381   ierr = PetscOptionsHead("GAMG options");CHKERRQ(ierr);
1382   {
1383     /* -pc_gamg_verbose */
1384     ierr = PetscOptionsInt("-pc_gamg_verbose","Verbose (debugging) output for PCGAMG",
1385                            "none", pc_gamg->verbose,
1386                            &pc_gamg->verbose, NULL);CHKERRQ(ierr);
1387     /* -pc_gamg_repartition */
1388     ierr = PetscOptionsBool("-pc_gamg_repartition",
1389                             "Repartion coarse grids (false)",
1390                             "PCGAMGRepartitioning",
1391                             pc_gamg->repart,
1392                             &pc_gamg->repart,
1393                             &flag);CHKERRQ(ierr);
1394     /* -pc_gamg_reuse_interpolation */
1395     ierr = PetscOptionsBool("-pc_gamg_reuse_interpolation",
1396                             "Reuse prolongation operator (true)",
1397                             "PCGAMGReuseProl",
1398                             pc_gamg->reuse_prol,
1399                             &pc_gamg->reuse_prol,
1400                             &flag);CHKERRQ(ierr);
1401     /* -pc_gamg_use_agg_gasm */
1402     ierr = PetscOptionsBool("-pc_gamg_use_agg_gasm",
1403                             "Use aggregation agragates for GASM smoother (false)",
1404                             "PCGAMGUseASMAggs",
1405                             pc_gamg->use_aggs_in_gasm,
1406                             &pc_gamg->use_aggs_in_gasm,
1407                             &flag);CHKERRQ(ierr);
1408     /* -pc_gamg_process_eq_limit */
1409     ierr = PetscOptionsInt("-pc_gamg_process_eq_limit",
1410                            "Limit (goal) on number of equations per process on coarse grids",
1411                            "PCGAMGSetProcEqLim",
1412                            pc_gamg->min_eq_proc,
1413                            &pc_gamg->min_eq_proc,
1414                            &flag);CHKERRQ(ierr);
1415     /* -pc_gamg_coarse_eq_limit */
1416     ierr = PetscOptionsInt("-pc_gamg_coarse_eq_limit",
1417                            "Limit on number of equations for the coarse grid",
1418                            "PCGAMGSetCoarseEqLim",
1419                            pc_gamg->coarse_eq_limit,
1420                            &pc_gamg->coarse_eq_limit,
1421                            &flag);CHKERRQ(ierr);
1422     /* -pc_gamg_threshold */
1423     ierr = PetscOptionsReal("-pc_gamg_threshold",
1424                             "Relative threshold to use for dropping edges in aggregation graph",
1425                             "PCGAMGSetThreshold",
1426                             pc_gamg->threshold,
1427                             &pc_gamg->threshold,
1428                             &flag);CHKERRQ(ierr);
1429     if (flag && pc_gamg->verbose) {
1430       ierr = PetscPrintf(wcomm,"\t[%d]%s threshold set %e\n",0,__FUNCT__,pc_gamg->threshold);CHKERRQ(ierr);
1431     }
1432 
1433     ierr = PetscOptionsRealArray("-pc_gamg_eigtarget","Target eigenvalue range as fraction of estimated maximum eigenvalue","PCGAMGSetEigTarget",pc_gamg->eigtarget,&two,NULL);CHKERRQ(ierr);
1434     ierr = PetscOptionsInt("-pc_mg_levels",
1435                            "Set number of MG levels",
1436                            "PCGAMGSetNlevels",
1437                            pc_gamg->Nlevels,
1438                            &pc_gamg->Nlevels,
1439                            &flag);CHKERRQ(ierr);
1440   }
1441   ierr = PetscOptionsTail();CHKERRQ(ierr);
1442   PetscFunctionReturn(0);
1443 }
1444 
1445 /* -------------------------------------------------------------------------- */
1446 /*MC
1447      PCGAMG - Geometric algebraic multigrid (AMG) preconditioning framework.
1448        - This is the entry point to GAMG, registered in pcregis.c
1449 
1450    Options Database Keys:
1451    Multigrid options(inherited)
1452 +  -pc_mg_cycles <1>: 1 for V cycle, 2 for W-cycle (PCMGSetCycleType)
1453 .  -pc_mg_smoothup <1>: Number of post-smoothing steps (PCMGSetNumberSmoothUp)
1454 .  -pc_mg_smoothdown <1>: Number of pre-smoothing steps (PCMGSetNumberSmoothDown)
1455 -  -pc_mg_type <multiplicative>: (one of) additive multiplicative full kascade
1456 
1457   Level: intermediate
1458 
1459   Concepts: multigrid
1460 
1461 .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC, PCMGType,
1462            PCMGSetLevels(), PCMGGetLevels(), PCMGSetType(), PCMGSetCycleType(), PCMGSetNumberSmoothDown(),
1463            PCMGSetNumberSmoothUp(), PCMGGetCoarseSolve(), PCMGSetResidual(), PCMGSetInterpolation(),
1464            PCMGSetRestriction(), PCMGGetSmoother(), PCMGGetSmootherUp(), PCMGGetSmootherDown(),
1465            PCMGSetCyclesOnLevel(), PCMGSetRhs(), PCMGSetX(), PCMGSetR()
1466 M*/
1467 EXTERN_C_BEGIN
1468 #undef __FUNCT__
1469 #define __FUNCT__ "PCCreate_GAMG"
1470 PetscErrorCode  PCCreate_GAMG(PC pc)
1471 {
1472   PetscErrorCode ierr;
1473   PC_GAMG        *pc_gamg;
1474   PC_MG          *mg;
1475 #if defined PETSC_GAMG_USE_LOG
1476   static long count = 0;
1477 #endif
1478 
1479   PetscFunctionBegin;
1480   /* PCGAMG is an inherited class of PCMG. Initialize pc as PCMG */
1481   ierr = PCSetType(pc, PCMG);CHKERRQ(ierr); /* calls PCCreate_MG() and MGCreate_Private() */
1482   ierr = PetscObjectChangeTypeName((PetscObject)pc, PCGAMG);CHKERRQ(ierr);
1483 
1484   /* create a supporting struct and attach it to pc */
1485   ierr         = PetscNewLog(pc, PC_GAMG, &pc_gamg);CHKERRQ(ierr);
1486   mg           = (PC_MG*)pc->data;
1487   mg->galerkin = 2;             /* Use Galerkin, but it is computed externally */
1488   mg->innerctx = pc_gamg;
1489 
1490   pc_gamg->setup_count = 0;
1491   /* these should be in subctx but repartitioning needs simple arrays */
1492   pc_gamg->data_sz = 0;
1493   pc_gamg->data    = 0;
1494 
1495   /* register AMG type */
1496   if (!GAMGList) {
1497     ierr = PetscFunctionListAdd(PETSC_COMM_WORLD,&GAMGList,GAMGGEO,"PCCreateGAMG_GEO",(void (*)(void))PCCreateGAMG_GEO);CHKERRQ(ierr);
1498     ierr = PetscFunctionListAdd(PETSC_COMM_WORLD,&GAMGList,GAMGAGG,"PCCreateGAMG_AGG",(void (*)(void))PCCreateGAMG_AGG);CHKERRQ(ierr);
1499   }
1500 
1501   /* overwrite the pointers of PCMG by the functions of base class PCGAMG */
1502   pc->ops->setfromoptions = PCSetFromOptions_GAMG;
1503   pc->ops->setup          = PCSetUp_GAMG;
1504   pc->ops->reset          = PCReset_GAMG;
1505   pc->ops->destroy        = PCDestroy_GAMG;
1506 
1507   ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,
1508                                            "PCGAMGSetProcEqLim_C",
1509                                            "PCGAMGSetProcEqLim_GAMG",
1510                                            PCGAMGSetProcEqLim_GAMG);CHKERRQ(ierr);
1511   ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,
1512                                            "PCGAMGSetCoarseEqLim_C",
1513                                            "PCGAMGSetCoarseEqLim_GAMG",
1514                                            PCGAMGSetCoarseEqLim_GAMG);CHKERRQ(ierr);
1515   ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,
1516                                            "PCGAMGSetRepartitioning_C",
1517                                            "PCGAMGSetRepartitioning_GAMG",
1518                                            PCGAMGSetRepartitioning_GAMG);CHKERRQ(ierr);
1519   ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,
1520                                            "PCGAMGSetReuseProl_C",
1521                                            "PCGAMGSetReuseProl_GAMG",
1522                                            PCGAMGSetReuseProl_GAMG);CHKERRQ(ierr);
1523   ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,
1524                                            "PCGAMGSetUseASMAggs_C",
1525                                            "PCGAMGSetUseASMAggs_GAMG",
1526                                            PCGAMGSetUseASMAggs_GAMG);CHKERRQ(ierr);
1527   ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,
1528                                            "PCGAMGSetThreshold_C",
1529                                            "PCGAMGSetThreshold_GAMG",
1530                                            PCGAMGSetThreshold_GAMG);CHKERRQ(ierr);
1531   ierr = PetscObjectComposeFunctionDynamic((PetscObject)pc,
1532                                            "PCGAMGSetType_C",
1533                                            "PCGAMGSetType_GAMG",
1534                                            PCGAMGSetType_GAMG);CHKERRQ(ierr);
1535   pc_gamg->repart           = PETSC_FALSE;
1536   pc_gamg->reuse_prol       = PETSC_TRUE;
1537   pc_gamg->use_aggs_in_gasm = PETSC_FALSE;
1538   pc_gamg->min_eq_proc      = 50;
1539   pc_gamg->coarse_eq_limit  = 800;
1540   pc_gamg->threshold        = 0.001;
1541   pc_gamg->Nlevels          = GAMG_MAXLEVELS;
1542   pc_gamg->verbose          = 0;
1543   pc_gamg->emax_id          = -1;
1544   pc_gamg->eigtarget[0]     = 0.05;
1545   pc_gamg->eigtarget[1]     = 1.05;
1546 
1547   /* private events */
1548 #if defined PETSC_GAMG_USE_LOG
1549   if (count++ == 0) {
1550     ierr = PetscLogEventRegister("GAMG: createProl", PC_CLASSID, &petsc_gamg_setup_events[SET1]);CHKERRQ(ierr);
1551     ierr = PetscLogEventRegister("  Graph", PC_CLASSID, &petsc_gamg_setup_events[GRAPH]);CHKERRQ(ierr);
1552     /* PetscLogEventRegister("    G.Mat", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_MAT]); */
1553     /* PetscLogEventRegister("    G.Filter", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_FILTER]); */
1554     /* PetscLogEventRegister("    G.Square", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_SQR]); */
1555     ierr = PetscLogEventRegister("  MIS/Agg", PC_CLASSID, &petsc_gamg_setup_events[SET4]);CHKERRQ(ierr);
1556     ierr = PetscLogEventRegister("  geo: growSupp", PC_CLASSID, &petsc_gamg_setup_events[SET5]);CHKERRQ(ierr);
1557     ierr = PetscLogEventRegister("  geo: triangle", PC_CLASSID, &petsc_gamg_setup_events[SET6]);CHKERRQ(ierr);
1558     ierr = PetscLogEventRegister("    search&set", PC_CLASSID, &petsc_gamg_setup_events[FIND_V]);CHKERRQ(ierr);
1559     ierr = PetscLogEventRegister("  SA: col data", PC_CLASSID, &petsc_gamg_setup_events[SET7]);CHKERRQ(ierr);
1560     ierr = PetscLogEventRegister("  SA: frmProl0", PC_CLASSID, &petsc_gamg_setup_events[SET8]);CHKERRQ(ierr);
1561     ierr = PetscLogEventRegister("  SA: smooth", PC_CLASSID, &petsc_gamg_setup_events[SET9]);CHKERRQ(ierr);
1562     ierr = PetscLogEventRegister("GAMG: partLevel", PC_CLASSID, &petsc_gamg_setup_events[SET2]);CHKERRQ(ierr);
1563     ierr = PetscLogEventRegister("  repartition", PC_CLASSID, &petsc_gamg_setup_events[SET12]);CHKERRQ(ierr);
1564     ierr = PetscLogEventRegister("  Invert-Sort", PC_CLASSID, &petsc_gamg_setup_events[SET13]);CHKERRQ(ierr);
1565     ierr = PetscLogEventRegister("  Move A", PC_CLASSID, &petsc_gamg_setup_events[SET14]);CHKERRQ(ierr);
1566     ierr = PetscLogEventRegister("  Move P", PC_CLASSID, &petsc_gamg_setup_events[SET15]);CHKERRQ(ierr);
1567 
1568     /* PetscLogEventRegister(" PL move data", PC_CLASSID, &petsc_gamg_setup_events[SET13]); */
1569     /* PetscLogEventRegister("GAMG: fix", PC_CLASSID, &petsc_gamg_setup_events[SET10]); */
1570     /* PetscLogEventRegister("GAMG: set levels", PC_CLASSID, &petsc_gamg_setup_events[SET11]); */
1571     /* create timer stages */
1572 #if defined GAMG_STAGES
1573     {
1574       char     str[32];
1575       PetscInt lidx;
1576       sprintf(str,"MG Level %d (finest)",0);
1577       ierr = PetscLogStageRegister(str, &gamg_stages[0]);CHKERRQ(ierr);
1578       for (lidx=1; lidx<9; lidx++) {
1579         sprintf(str,"MG Level %d",lidx);
1580         ierr = PetscLogStageRegister(str, &gamg_stages[lidx]);CHKERRQ(ierr);
1581       }
1582     }
1583 #endif
1584   }
1585 #endif
1586   /* general events */
1587 #if defined PETSC_USE_LOG
1588   ierr = PetscLogEventRegister("PCGAMGgraph_AGG", 0, &PC_GAMGGgraph_AGG);CHKERRQ(ierr);
1589   ierr = PetscLogEventRegister("PCGAMGgraph_GEO", PC_CLASSID, &PC_GAMGGgraph_GEO);CHKERRQ(ierr);
1590   ierr = PetscLogEventRegister("PCGAMGcoarse_AGG", PC_CLASSID, &PC_GAMGCoarsen_AGG);CHKERRQ(ierr);
1591   ierr = PetscLogEventRegister("PCGAMGcoarse_GEO", PC_CLASSID, &PC_GAMGCoarsen_GEO);CHKERRQ(ierr);
1592   ierr = PetscLogEventRegister("PCGAMGProl_AGG", PC_CLASSID, &PC_GAMGProlongator_AGG);CHKERRQ(ierr);
1593   ierr = PetscLogEventRegister("PCGAMGProl_GEO", PC_CLASSID, &PC_GAMGProlongator_GEO);CHKERRQ(ierr);
1594   ierr = PetscLogEventRegister("PCGAMGPOpt_AGG", PC_CLASSID, &PC_GAMGOptprol_AGG);CHKERRQ(ierr);
1595   ierr = PetscLogEventRegister("GAMGKKTProl_AGG", PC_CLASSID, &PC_GAMGKKTProl_AGG);CHKERRQ(ierr);
1596 #endif
1597 
1598   /* instantiate derived type */
1599   ierr = PetscOptionsHead("GAMG options");CHKERRQ(ierr);
1600   {
1601     char tname[256] = GAMGAGG;
1602     ierr = PetscOptionsList("-pc_gamg_type","Type of GAMG method","PCGAMGSetType",GAMGList, tname, tname, sizeof(tname), NULL);CHKERRQ(ierr);
1603     ierr = PCGAMGSetType(pc, tname);CHKERRQ(ierr);
1604   }
1605   ierr = PetscOptionsTail();CHKERRQ(ierr);
1606   PetscFunctionReturn(0);
1607 }
1608 EXTERN_C_END
1609