xref: /petsc/src/ksp/pc/impls/gamg/gamg.c (revision f2c2a1b97ba623b07d38ea716c110451b7b5ea3c)
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 
8 #if defined PETSC_GAMG_USE_LOG
9 PetscLogEvent petsc_gamg_setup_events[NUM_SET];
10 #endif
11 
12 #if defined PETSC_USE_LOG
13 PetscLogEvent PC_GAMGGgraph_AGG;
14 PetscLogEvent PC_GAMGGgraph_GEO;
15 PetscLogEvent PC_GAMGCoarsen_AGG;
16 PetscLogEvent PC_GAMGCoarsen_GEO;
17 PetscLogEvent PC_GAMGProlongator_AGG;
18 PetscLogEvent PC_GAMGProlongator_GEO;
19 PetscLogEvent PC_GAMGOptprol_AGG;
20 PetscLogEvent PC_GAMGKKTProl_AGG;
21 #endif
22 
23 #define GAMG_MAXLEVELS 30
24 
25 /* #define GAMG_STAGES */
26 #if (defined PETSC_GAMG_USE_LOG && defined GAMG_STAGES)
27 static PetscLogStage gamg_stages[GAMG_MAXLEVELS];
28 #endif
29 
30 static PetscFList GAMGList = 0;
31 
32 /* ----------------------------------------------------------------------------- */
33 #undef __FUNCT__
34 #define __FUNCT__ "PCReset_GAMG"
35 PetscErrorCode PCReset_GAMG(PC pc)
36 {
37   PetscErrorCode  ierr;
38   PC_MG           *mg = (PC_MG*)pc->data;
39   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
40 
41   PetscFunctionBegin;
42   if ( pc_gamg->data ) { /* this should not happen, cleaned up in SetUp */
43     PetscPrintf(((PetscObject)pc)->comm,"***[%d]%s this should not happen, cleaned up in SetUp\n",0,__FUNCT__);
44     ierr = PetscFree( pc_gamg->data ); CHKERRQ(ierr);
45   }
46   pc_gamg->data = PETSC_NULL; pc_gamg->data_sz = 0;
47 
48   if ( pc_gamg->orig_data ) {
49     ierr = PetscFree( pc_gamg->orig_data ); CHKERRQ(ierr);
50   }
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     out->prim_is = is_prime;
76     out->constr_is = is_constraint;
77 
78     ierr = MatGetSubMatrix( A, is_prime, is_prime,      MAT_INITIAL_MATRIX, &out->A11); CHKERRQ(ierr);
79     ierr = MatGetSubMatrix( A, is_prime, is_constraint, MAT_INITIAL_MATRIX, &out->A12); CHKERRQ(ierr);
80     ierr = MatGetSubMatrix( A, is_constraint, is_prime, MAT_INITIAL_MATRIX, &out->A21); CHKERRQ(ierr);
81   }
82   else {
83     out->A11 = A;
84     out->A21 = PETSC_NULL;
85     out->A12 = PETSC_NULL;
86     out->prim_is = PETSC_NULL;
87     out->constr_is = PETSC_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 
108   PetscFunctionReturn(0);
109 }
110 
111 /* -------------------------------------------------------------------------- */
112 /*
113    createLevel: create coarse op with RAP.  repartition and/or reduce number
114      of active processors.
115 
116    Input Parameter:
117    . pc - parameters + side effect: coarse data in 'pc_gamg->data' and
118           'pc_gamg->data_sz' are changed via repartitioning/reduction.
119    . Amat_fine - matrix on this fine (k) level
120    . cr_bs - coarse block size
121    . isLast -
122    . stokes -
123    In/Output Parameter:
124    . a_P_inout - prolongation operator to the next level (k-->k-1)
125    . a_nactive_proc - number of active procs
126    Output Parameter:
127    . a_Amat_crs - coarse matrix that is created (k-1)
128 */
129 
130 #undef __FUNCT__
131 #define __FUNCT__ "createLevel"
132 static PetscErrorCode createLevel( const PC pc,
133                                    const Mat Amat_fine,
134                                    const PetscInt cr_bs,
135                                    const PetscBool isLast,
136                                    const PetscBool stokes,
137                                    Mat *a_P_inout,
138                                    Mat *a_Amat_crs,
139                                    PetscMPIInt *a_nactive_proc
140                                    )
141 {
142   PetscErrorCode   ierr;
143   PC_MG           *mg = (PC_MG*)pc->data;
144   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
145   const PetscBool  repart = pc_gamg->repart;
146   const PetscInt   min_eq_proc = pc_gamg->min_eq_proc, coarse_max = pc_gamg->coarse_eq_limit;
147   Mat              Cmat,Pold=*a_P_inout;
148   MPI_Comm         wcomm = ((PetscObject)Amat_fine)->comm;
149   PetscMPIInt      mype,npe,new_npe,nactive=*a_nactive_proc;
150   PetscInt         ncrs_eq,ncrs_prim,f_bs;
151 
152   PetscFunctionBegin;
153   ierr = MPI_Comm_rank( wcomm, &mype ); CHKERRQ(ierr);
154   ierr = MPI_Comm_size( wcomm, &npe );  CHKERRQ(ierr);
155   ierr = MatGetBlockSize( Amat_fine, &f_bs ); CHKERRQ(ierr);
156   /* RAP */
157   ierr = MatPtAP( Amat_fine, Pold, MAT_INITIAL_MATRIX, 2.0, &Cmat ); CHKERRQ(ierr);
158 
159   /* set 'ncrs_prim' (nodes), 'ncrs_eq' (equations)*/
160   ncrs_prim = pc_gamg->data_sz/pc_gamg->data_cell_cols/pc_gamg->data_cell_rows;
161   assert(pc_gamg->data_sz%(pc_gamg->data_cell_cols*pc_gamg->data_cell_rows)==0);
162   ierr = MatGetLocalSize( Cmat, &ncrs_eq, PETSC_NULL );  CHKERRQ(ierr);
163 
164   /* get number of PEs to make active 'new_npe', reduce, can be any integer 1-P */
165   {
166     PetscInt ncrs_eq_glob;
167     ierr = MatGetSize( Cmat, &ncrs_eq_glob, PETSC_NULL );  CHKERRQ(ierr);
168     new_npe = (PetscMPIInt)((float)ncrs_eq_glob/(float)min_eq_proc + 0.5); /* hardwire min. number of eq/proc */
169     if ( new_npe == 0 || ncrs_eq_glob < coarse_max ) new_npe = 1;
170     else if ( new_npe >= nactive ) new_npe = nactive; /* no change, rare */
171     if ( isLast ) new_npe = 1;
172   }
173 
174   if ( !repart && new_npe==nactive ) {
175     *a_Amat_crs = Cmat; /* output - no repartitioning or reduction - could bail here */
176   }
177   else {
178     const PetscInt *idx,ndata_rows=pc_gamg->data_cell_rows,ndata_cols=pc_gamg->data_cell_cols,node_data_sz=ndata_rows*ndata_cols;
179     PetscInt       *counts,*newproc_idx,ii,jj,kk,strideNew,*tidx,ncrs_prim_new,ncrs_eq_new,nloc_old;
180     IS              is_eq_newproc,is_eq_newproc_prim,is_eq_num,is_eq_num_prim,isscat,new_eq_indices;
181     VecScatter      vecscat;
182     PetscScalar    *array;
183     Vec             src_crd, dest_crd;
184 
185     nloc_old = ncrs_eq/cr_bs; assert(ncrs_eq%cr_bs==0);
186 #if defined PETSC_GAMG_USE_LOG
187     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET12],0,0,0,0);CHKERRQ(ierr);
188 #endif
189     /* make 'is_eq_newproc' */
190     ierr = PetscMalloc( npe*sizeof(PetscInt), &counts ); CHKERRQ(ierr);
191     if ( repart && !stokes ) {
192       /* Repartition Cmat_{k} and move colums of P^{k}_{k-1} and coordinates of primal part accordingly */
193       Mat             adj;
194 
195       if (pc_gamg->verbose>0) {
196         if (pc_gamg->verbose==1) PetscPrintf(wcomm,"\t[%d]%s repartition: npe (active): %d --> %d, neq = %d\n",mype,__FUNCT__,*a_nactive_proc,new_npe,ncrs_eq);
197         else {
198           PetscInt n;
199           ierr = MPI_Allreduce( &ncrs_eq, &n, 1, MPIU_INT, MPI_SUM, wcomm );CHKERRQ(ierr);
200           PetscPrintf(wcomm,"\t[%d]%s repartition: npe (active): %d --> %d, neq = %d\n",mype,__FUNCT__,*a_nactive_proc,new_npe,n);
201         }
202       }
203 
204       /* get 'adj' */
205       if ( cr_bs == 1 ) {
206 	ierr = MatConvert( Cmat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
207       }
208       else{
209 	/* make a scalar matrix to partition (no Stokes here) */
210 	Mat tMat;
211 	PetscInt Istart_crs,Iend_crs,ncols,jj,Ii;
212 	const PetscScalar *vals;
213 	const PetscInt *idx;
214 	PetscInt *d_nnz, *o_nnz, M, N;
215 	static PetscInt llev = 0;
216 
217 	ierr = PetscMalloc( ncrs_prim*sizeof(PetscInt), &d_nnz ); CHKERRQ(ierr);
218 	ierr = PetscMalloc( ncrs_prim*sizeof(PetscInt), &o_nnz ); CHKERRQ(ierr);
219         ierr = MatGetOwnershipRange( Cmat, &Istart_crs, &Iend_crs );    CHKERRQ(ierr);
220         ierr = MatGetSize( Cmat, &M, &N );CHKERRQ(ierr);
221 	for ( Ii = Istart_crs, jj = 0 ; Ii < Iend_crs ; Ii += cr_bs, jj++ ) {
222 	  ierr = MatGetRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
223 	  d_nnz[jj] = ncols/cr_bs;
224 	  o_nnz[jj] = ncols/cr_bs;
225 	  ierr = MatRestoreRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
226 	  if ( d_nnz[jj] > ncrs_prim ) d_nnz[jj] = ncrs_prim;
227 	  if ( o_nnz[jj] > (M/cr_bs-ncrs_prim) ) o_nnz[jj] = M/cr_bs-ncrs_prim;
228 	}
229 
230 	ierr = MatCreate( wcomm, &tMat ); CHKERRQ(ierr);
231 	ierr = MatSetSizes( tMat, ncrs_prim, ncrs_prim,
232                             PETSC_DETERMINE, PETSC_DETERMINE );
233         CHKERRQ(ierr);
234         ierr = MatSetType(tMat,MATAIJ);   CHKERRQ(ierr);
235         ierr = MatSeqAIJSetPreallocation(tMat,0,d_nnz);CHKERRQ(ierr);
236         ierr = MatMPIAIJSetPreallocation(tMat,0,d_nnz,0,o_nnz);CHKERRQ(ierr);
237 	ierr = PetscFree( d_nnz ); CHKERRQ(ierr);
238 	ierr = PetscFree( o_nnz ); CHKERRQ(ierr);
239 
240 	for ( ii = Istart_crs; ii < Iend_crs; ii++ ) {
241 	  PetscInt dest_row = ii/cr_bs;
242 	  ierr = MatGetRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
243 	  for ( jj = 0 ; jj < ncols ; jj++ ){
244 	    PetscInt dest_col = idx[jj]/cr_bs;
245 	    PetscScalar v = 1.0;
246 	    ierr = MatSetValues(tMat,1,&dest_row,1,&dest_col,&v,ADD_VALUES); CHKERRQ(ierr);
247 	  }
248 	  ierr = MatRestoreRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
249 	}
250 	ierr = MatAssemblyBegin(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
251 	ierr = MatAssemblyEnd(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
252 
253 	if ( llev++ == -1 ) {
254 	  PetscViewer viewer; char fname[32];
255 	  ierr = PetscSNPrintf(fname,sizeof(fname),"part_mat_%D.mat",llev);CHKERRQ(ierr);
256 	  PetscViewerBinaryOpen(wcomm,fname,FILE_MODE_WRITE,&viewer);
257 	  ierr = MatView( tMat, viewer ); CHKERRQ(ierr);
258 	  ierr = PetscViewerDestroy( &viewer );
259 	}
260 
261 	ierr = MatConvert( tMat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
262 
263 	ierr = MatDestroy( &tMat );  CHKERRQ(ierr);
264       } /* create 'adj' */
265 
266       { /* partition: get newproc_idx */
267 	char prefix[256];
268 	const char *pcpre;
269 	const PetscInt *is_idx;
270 	MatPartitioning  mpart;
271 	IS proc_is;
272 	PetscInt targetPE;
273 
274 	ierr = MatPartitioningCreate( wcomm, &mpart ); CHKERRQ(ierr);
275 	ierr = MatPartitioningSetAdjacency( mpart, adj ); CHKERRQ(ierr);
276 	ierr = PCGetOptionsPrefix( pc, &pcpre );CHKERRQ(ierr);
277 	ierr = PetscSNPrintf(prefix,sizeof(prefix),"%spc_gamg_",pcpre?pcpre:"");CHKERRQ(ierr);
278 	ierr = PetscObjectSetOptionsPrefix((PetscObject)mpart,prefix);CHKERRQ(ierr);
279 	ierr = MatPartitioningSetFromOptions( mpart );    CHKERRQ(ierr);
280 	ierr = MatPartitioningSetNParts( mpart, new_npe );CHKERRQ(ierr);
281 	ierr = MatPartitioningApply( mpart, &proc_is ); CHKERRQ(ierr);
282 	ierr = MatPartitioningDestroy( &mpart );          CHKERRQ(ierr);
283 
284 	/* collect IS info */
285 	ierr = PetscMalloc( ncrs_eq*sizeof(PetscInt), &newproc_idx ); CHKERRQ(ierr);
286 	ierr = ISGetIndices( proc_is, &is_idx );        CHKERRQ(ierr);
287 	targetPE = 1; /* bring to "front" of machine */
288 	/*targetPE = npe/new_npe;*/ /* spread partitioning across machine */
289 	for ( kk = jj = 0 ; kk < nloc_old ; kk++ ){
290 	  for ( ii = 0 ; ii < cr_bs ; ii++, jj++ ){
291 	    newproc_idx[jj] = is_idx[kk] * targetPE; /* distribution */
292 	  }
293 	}
294 	ierr = ISRestoreIndices( proc_is, &is_idx );     CHKERRQ(ierr);
295 	ierr = ISDestroy( &proc_is );                    CHKERRQ(ierr);
296       }
297       ierr = MatDestroy( &adj );                       CHKERRQ(ierr);
298 
299       ierr = ISCreateGeneral( wcomm, ncrs_eq, newproc_idx, PETSC_COPY_VALUES, &is_eq_newproc );
300       CHKERRQ(ierr);
301       if ( newproc_idx != 0 ) {
302 	ierr = PetscFree( newproc_idx );  CHKERRQ(ierr);
303       }
304     } /* repartitioning */
305     else { /* simple aggreagtion of parts -- 'is_eq_newproc' */
306 
307       PetscInt rfactor,targetPE;
308       /* find factor */
309       if ( new_npe == 1 ) rfactor = npe; /* easy */
310       else {
311 	PetscReal best_fact = 0.;
312 	jj = -1;
313 	for ( kk = 1 ; kk <= npe ; kk++ ){
314 	  if ( npe%kk==0 ) { /* a candidate */
315 	    PetscReal nactpe = (PetscReal)npe/(PetscReal)kk, fact = nactpe/(PetscReal)new_npe;
316 	    if (fact > 1.0) fact = 1./fact; /* keep fact < 1 */
317 	    if ( fact > best_fact ) {
318 	      best_fact = fact; jj = kk;
319 	    }
320 	  }
321 	}
322 	if ( jj != -1 ) rfactor = jj;
323 	else rfactor = 1; /* does this happen .. a prime */
324       }
325       new_npe = npe/rfactor;
326 
327       if ( new_npe==nactive ) {
328 	*a_Amat_crs = Cmat; /* output - no repartitioning or reduction, bail out because nested here */
329 	ierr = PetscFree( counts );  CHKERRQ(ierr);
330 	if (pc_gamg->verbose>0){
331           PetscPrintf(wcomm,"\t[%d]%s aggregate processors noop: new_npe=%d, neq(loc)=%d\n",mype,__FUNCT__,new_npe,ncrs_eq);
332         }
333 	PetscFunctionReturn(0);
334       }
335 
336       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s number of equations (loc) %d with simple aggregation\n",mype,__FUNCT__,ncrs_eq);
337       targetPE = mype/rfactor;
338       ierr = ISCreateStride( wcomm, ncrs_eq, targetPE, 0, &is_eq_newproc ); CHKERRQ(ierr);
339 
340       if ( stokes ) {
341         ierr = ISCreateStride( wcomm, ncrs_prim*cr_bs, targetPE, 0, &is_eq_newproc_prim ); CHKERRQ(ierr);
342       }
343     } /* end simple 'is_eq_newproc' */
344 
345     /*
346      Create an index set from the is_eq_newproc index set to indicate the mapping TO
347      */
348     ierr = ISPartitioningToNumbering( is_eq_newproc, &is_eq_num ); CHKERRQ(ierr);
349     if ( stokes ) {
350       ierr = ISPartitioningToNumbering( is_eq_newproc_prim, &is_eq_num_prim ); CHKERRQ(ierr);
351     }
352     else is_eq_num_prim = is_eq_num;
353     /*
354       Determine how many equations/vertices are assigned to each processor
355      */
356     ierr = ISPartitioningCount( is_eq_newproc, npe, counts ); CHKERRQ(ierr);
357     ncrs_eq_new = counts[mype];
358     ierr = ISDestroy( &is_eq_newproc );                       CHKERRQ(ierr);
359     if ( stokes ) {
360       ierr = ISPartitioningCount( is_eq_newproc_prim, npe, counts ); CHKERRQ(ierr);
361       ierr = ISDestroy( &is_eq_newproc_prim );                       CHKERRQ(ierr);
362       ncrs_prim_new = counts[mype]/cr_bs; /* nodes */
363     }
364     else ncrs_prim_new = ncrs_eq_new/cr_bs; /* eqs */
365 
366     ierr = PetscFree( counts );  CHKERRQ(ierr);
367 #if defined PETSC_GAMG_USE_LOG
368     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET12],0,0,0,0);   CHKERRQ(ierr);
369 #endif
370 
371     /* move data (for primal equations only) */
372     /* Create a vector to contain the newly ordered element information */
373     ierr = VecCreate( wcomm, &dest_crd );
374     ierr = VecSetSizes( dest_crd, node_data_sz*ncrs_prim_new, PETSC_DECIDE ); CHKERRQ(ierr);
375     ierr = VecSetFromOptions( dest_crd ); CHKERRQ(ierr); /* this is needed! */
376     /*
377      There are 'ndata_rows*ndata_cols' data items per node, (one can think of the vectors of having
378      a block size of ...).  Note, ISs are expanded into equation space by 'cr_bs'.
379      */
380     ierr = PetscMalloc( (ncrs_prim*node_data_sz)*sizeof(PetscInt), &tidx ); CHKERRQ(ierr);
381     ierr = ISGetIndices( is_eq_num_prim, &idx ); CHKERRQ(ierr);
382     for (ii=0,jj=0; ii<ncrs_prim ; ii++) {
383       PetscInt id = idx[ii*cr_bs]/cr_bs; /* get node back */
384       for ( kk=0; kk<node_data_sz ; kk++, jj++) tidx[jj] = id*node_data_sz + kk;
385     }
386     ierr = ISRestoreIndices( is_eq_num_prim, &idx ); CHKERRQ(ierr);
387     ierr = ISCreateGeneral( wcomm, node_data_sz*ncrs_prim, tidx, PETSC_COPY_VALUES, &isscat );
388     CHKERRQ(ierr);
389     ierr = PetscFree( tidx );  CHKERRQ(ierr);
390     /*
391      Create a vector to contain the original vertex information for each element
392      */
393     ierr = VecCreateSeq( PETSC_COMM_SELF, node_data_sz*ncrs_prim, &src_crd ); CHKERRQ(ierr);
394     for ( jj=0; jj<ndata_cols ; jj++ ) {
395       const PetscInt stride0=ncrs_prim*pc_gamg->data_cell_rows;
396       for ( ii=0 ; ii<ncrs_prim ; ii++) {
397 	for ( kk=0; kk<ndata_rows ; kk++ ) {
398 	  PetscInt ix = ii*ndata_rows + kk + jj*stride0, jx = ii*node_data_sz + kk*ndata_cols + jj;
399           PetscScalar tt = (PetscScalar)pc_gamg->data[ix];
400 	  ierr = VecSetValues( src_crd, 1, &jx, &tt, INSERT_VALUES );  CHKERRQ(ierr);
401 	}
402       }
403     }
404     ierr = VecAssemblyBegin(src_crd); CHKERRQ(ierr);
405     ierr = VecAssemblyEnd(src_crd); CHKERRQ(ierr);
406     /*
407       Scatter the element vertex information (still in the original vertex ordering)
408       to the correct processor
409     */
410     ierr = VecScatterCreate( src_crd, PETSC_NULL, dest_crd, isscat, &vecscat);
411     CHKERRQ(ierr);
412     ierr = ISDestroy( &isscat );       CHKERRQ(ierr);
413     ierr = VecScatterBegin(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
414     ierr = VecScatterEnd(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
415     ierr = VecScatterDestroy( &vecscat );       CHKERRQ(ierr);
416     ierr = VecDestroy( &src_crd );       CHKERRQ(ierr);
417     /*
418       Put the element vertex data into a new allocation of the gdata->ele
419     */
420     ierr = PetscFree( pc_gamg->data );    CHKERRQ(ierr);
421     ierr = PetscMalloc( node_data_sz*ncrs_prim_new*sizeof(PetscReal), &pc_gamg->data );    CHKERRQ(ierr);
422     pc_gamg->data_sz = node_data_sz*ncrs_prim_new;
423     strideNew = ncrs_prim_new*ndata_rows;
424     ierr = VecGetArray( dest_crd, &array );    CHKERRQ(ierr);
425     for ( jj=0; jj<ndata_cols ; jj++ ) {
426       for ( ii=0 ; ii<ncrs_prim_new ; ii++) {
427 	for ( kk=0; kk<ndata_rows ; kk++ ) {
428 	  PetscInt ix = ii*ndata_rows + kk + jj*strideNew, jx = ii*node_data_sz + kk*ndata_cols + jj;
429 	  pc_gamg->data[ix] = PetscRealPart(array[jx]);
430 	}
431       }
432     }
433     ierr = VecRestoreArray( dest_crd, &array );    CHKERRQ(ierr);
434     ierr = VecDestroy( &dest_crd );    CHKERRQ(ierr);
435 
436     /* move A and P (columns) with new layout */
437 #if defined PETSC_GAMG_USE_LOG
438     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
439 #endif
440 
441     /*
442       Invert for MatGetSubMatrix
443     */
444     ierr = ISInvertPermutation( is_eq_num, ncrs_eq_new, &new_eq_indices ); CHKERRQ(ierr);
445     ierr = ISSort( new_eq_indices ); CHKERRQ(ierr); /* is this needed? */
446     ierr = ISSetBlockSize( new_eq_indices, cr_bs );   CHKERRQ(ierr);
447     if (is_eq_num != is_eq_num_prim) {
448       ierr = ISDestroy( &is_eq_num_prim ); CHKERRQ(ierr); /* could be same as 'is_eq_num' */
449     }
450     ierr = ISDestroy( &is_eq_num ); CHKERRQ(ierr);
451 #if defined PETSC_GAMG_USE_LOG
452     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
453     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
454 #endif
455     /* 'a_Amat_crs' output */
456     {
457       Mat mat;
458       ierr = MatGetSubMatrix( Cmat, new_eq_indices, new_eq_indices, MAT_INITIAL_MATRIX, &mat );
459       CHKERRQ(ierr);
460       *a_Amat_crs = mat;
461 
462       if (!PETSC_TRUE){
463         PetscInt cbs, rbs;
464         ierr = MatGetBlockSizes( Cmat, &rbs, &cbs ); CHKERRQ(ierr);
465         PetscPrintf(MPI_COMM_SELF,"[%d]%s Old Mat rbs=%d cbs=%d\n",mype,__FUNCT__,rbs,cbs);
466         ierr = MatGetBlockSizes( mat, &rbs, &cbs ); CHKERRQ(ierr);
467         PetscPrintf(MPI_COMM_SELF,"[%d]%s New Mat rbs=%d cbs=%d cr_bs=%d\n",mype,__FUNCT__,rbs,cbs,cr_bs);
468       }
469     }
470     ierr = MatDestroy( &Cmat ); CHKERRQ(ierr);
471 
472 #if defined PETSC_GAMG_USE_LOG
473     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
474 #endif
475     /* prolongator */
476     {
477       IS findices;
478       PetscInt Istart,Iend;
479       Mat Pnew;
480       ierr = MatGetOwnershipRange( Pold, &Istart, &Iend );    CHKERRQ(ierr);
481 #if defined PETSC_GAMG_USE_LOG
482       ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
483 #endif
484       ierr = ISCreateStride(wcomm,Iend-Istart,Istart,1,&findices);   CHKERRQ(ierr);
485       ierr = ISSetBlockSize(findices,f_bs);   CHKERRQ(ierr);
486       ierr = MatGetSubMatrix( Pold, findices, new_eq_indices, MAT_INITIAL_MATRIX, &Pnew );
487       CHKERRQ(ierr);
488       ierr = ISDestroy( &findices ); CHKERRQ(ierr);
489 
490       if (!PETSC_TRUE){
491         PetscInt cbs, rbs;
492         ierr = MatGetBlockSizes( Pold, &rbs, &cbs ); CHKERRQ(ierr);
493         PetscPrintf(MPI_COMM_SELF,"[%d]%s Pold rbs=%d cbs=%d\n",mype,__FUNCT__,rbs,cbs);
494         ierr = MatGetBlockSizes( Pnew, &rbs, &cbs ); CHKERRQ(ierr);
495         PetscPrintf(MPI_COMM_SELF,"[%d]%s Pnew rbs=%d cbs=%d\n",mype,__FUNCT__,rbs,cbs);
496       }
497 #if defined PETSC_GAMG_USE_LOG
498       ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
499 #endif
500       ierr = MatDestroy( a_P_inout ); CHKERRQ(ierr);
501 
502       /* output - repartitioned */
503       *a_P_inout = Pnew;
504     }
505     ierr = ISDestroy( &new_eq_indices ); CHKERRQ(ierr);
506 
507     *a_nactive_proc = new_npe; /* output */
508   }
509 
510   /* outout matrix data */
511   if ( !PETSC_TRUE ) {
512     PetscViewer viewer; char fname[32]; static int llev=0; Cmat = *a_Amat_crs;
513     if (llev==0) {
514       sprintf(fname,"Cmat_%d.m",llev++);
515       PetscViewerASCIIOpen(wcomm,fname,&viewer);
516       ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
517       ierr = MatView(Amat_fine, viewer ); CHKERRQ(ierr);
518       ierr = PetscViewerDestroy( &viewer );
519     }
520     sprintf(fname,"Cmat_%d.m",llev++);
521     PetscViewerASCIIOpen(wcomm,fname,&viewer);
522     ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
523     ierr = MatView(Cmat, viewer ); CHKERRQ(ierr);
524     ierr = PetscViewerDestroy( &viewer );
525   }
526 
527   PetscFunctionReturn(0);
528 }
529 
530 /* -------------------------------------------------------------------------- */
531 /*
532    PCSetUp_GAMG - Prepares for the use of the GAMG preconditioner
533                     by setting data structures and options.
534 
535    Input Parameter:
536 .  pc - the preconditioner context
537 
538    Application Interface Routine: PCSetUp()
539 
540    Notes:
541    The interface routine PCSetUp() is not usually called directly by
542    the user, but instead is called by PCApply() if necessary.
543 */
544 #undef __FUNCT__
545 #define __FUNCT__ "PCSetUp_GAMG"
546 PetscErrorCode PCSetUp_GAMG( PC pc )
547 {
548   PetscErrorCode  ierr;
549   PC_MG           *mg = (PC_MG*)pc->data;
550   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
551   Mat              Pmat = pc->pmat;
552   PetscInt         fine_level,level,level1,bs,M,qq,lidx,nASMBlocksArr[GAMG_MAXLEVELS];
553   MPI_Comm         wcomm = ((PetscObject)pc)->comm;
554   PetscMPIInt      mype,npe,nactivepe;
555   Mat              Aarr[GAMG_MAXLEVELS],Parr[GAMG_MAXLEVELS];
556   PetscReal        emaxs[GAMG_MAXLEVELS];
557   IS              *ASMLocalIDsArr[GAMG_MAXLEVELS];
558   GAMGKKTMat       kktMatsArr[GAMG_MAXLEVELS];
559   PetscLogDouble   nnz0=0.,nnztot=0.;
560   MatInfo          info;
561   PetscBool        stokes = PETSC_FALSE, redo_mesh_setup = PETSC_FALSE;
562 
563   PetscFunctionBegin;
564   ierr = MPI_Comm_rank(wcomm,&mype);CHKERRQ(ierr);
565   ierr = MPI_Comm_size(wcomm,&npe);CHKERRQ(ierr);
566   if (pc_gamg->verbose>2) PetscPrintf(wcomm,"[%d]%s pc_gamg->setup_count=%d pc->setupcalled=%d\n",mype,__FUNCT__,pc_gamg->setup_count,pc->setupcalled);
567   if ( pc_gamg->setup_count++ > 0 ) {
568     if ( redo_mesh_setup ) {
569       /* reset everything */
570       ierr = PCReset_MG( pc ); CHKERRQ(ierr);
571       pc->setupcalled = 0;
572     }
573     else {
574       PC_MG_Levels **mglevels = mg->levels;
575       /* just do Galerkin grids */
576       Mat B,dA,dB;
577       assert(pc->setupcalled);
578 
579       if ( pc_gamg->Nlevels > 1 ) {
580         /* currently only handle case where mat and pmat are the same on coarser levels */
581         ierr = KSPGetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,&dA,&dB,PETSC_NULL);CHKERRQ(ierr);
582         /* (re)set to get dirty flag */
583         ierr = KSPSetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,dA,dB,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
584 
585         for (level=pc_gamg->Nlevels-2; level>-1; level--) {
586           /* the first time through the matrix structure has changed from repartitioning */
587           if ( pc_gamg->setup_count==2 /*&& (pc_gamg->repart || level==0)*/) {
588             ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_INITIAL_MATRIX,1.0,&B);CHKERRQ(ierr);
589             ierr = MatDestroy(&mglevels[level]->A);CHKERRQ(ierr);
590             mglevels[level]->A = B;
591           }
592           else {
593             ierr = KSPGetOperators(mglevels[level]->smoothd,PETSC_NULL,&B,PETSC_NULL);CHKERRQ(ierr);
594             ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_REUSE_MATRIX,1.0,&B);CHKERRQ(ierr);
595           }
596         ierr = KSPSetOperators(mglevels[level]->smoothd,B,B,SAME_NONZERO_PATTERN); CHKERRQ(ierr);
597         dB = B;
598         }
599       }
600 
601       ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
602 
603       /* PCSetUp_MG seems to insists on setting this to GMRES */
604       ierr = KSPSetType( mglevels[0]->smoothd, KSPPREONLY ); CHKERRQ(ierr);
605 
606       PetscFunctionReturn(0);
607     }
608   }
609 
610   ierr = PetscOptionsGetBool(((PetscObject)pc)->prefix,"-pc_fieldsplit_detect_saddle_point",&stokes,PETSC_NULL);CHKERRQ(ierr);
611 
612   ierr = GAMGKKTMatCreate( Pmat, stokes, &kktMatsArr[0] ); CHKERRQ(ierr);
613 
614   if ( !pc_gamg->data ) {
615     if ( pc_gamg->orig_data ) {
616       ierr = MatGetBlockSize( Pmat, &bs ); CHKERRQ(ierr);
617       ierr = MatGetLocalSize( Pmat, &qq, PETSC_NULL ); CHKERRQ(ierr);
618       pc_gamg->data_sz = (qq/bs)*pc_gamg->orig_data_cell_rows*pc_gamg->orig_data_cell_cols;
619       pc_gamg->data_cell_rows = pc_gamg->orig_data_cell_rows;
620       pc_gamg->data_cell_cols = pc_gamg->orig_data_cell_cols;
621       ierr = PetscMalloc( pc_gamg->data_sz*sizeof(PetscReal), &pc_gamg->data ); CHKERRQ(ierr);
622       for (qq=0;qq<pc_gamg->data_sz;qq++) pc_gamg->data[qq] = pc_gamg->orig_data[qq];
623     }
624     else {
625       if ( !pc_gamg->createdefaultdata ){
626         SETERRQ(wcomm,PETSC_ERR_PLIB,"'createdefaultdata' not set(?) need to support NULL data");
627       }
628       if ( stokes ) {
629         SETERRQ(wcomm,PETSC_ERR_PLIB,"Need data (eg, PCSetCoordinates) for Stokes problems");
630       }
631       ierr = pc_gamg->createdefaultdata( pc, kktMatsArr[0].A11 ); CHKERRQ(ierr);
632     }
633   }
634 
635   /* cache original data for reuse */
636   if ( !pc_gamg->orig_data && redo_mesh_setup ) {
637     ierr = PetscMalloc( pc_gamg->data_sz*sizeof(PetscReal), &pc_gamg->orig_data ); CHKERRQ(ierr);
638     for (qq=0;qq<pc_gamg->data_sz;qq++) pc_gamg->orig_data[qq] = pc_gamg->data[qq];
639     pc_gamg->orig_data_cell_rows = pc_gamg->data_cell_rows;
640     pc_gamg->orig_data_cell_cols = pc_gamg->data_cell_cols;
641   }
642 
643   /* get basic dims */
644   if ( stokes ) {
645     bs = pc_gamg->data_cell_rows; /* this is agg-mg specific */
646   }
647   else {
648     ierr = MatGetBlockSize( Pmat, &bs ); CHKERRQ(ierr);
649   }
650 
651   ierr = MatGetSize( Pmat, &M, &qq );CHKERRQ(ierr);
652   if (pc_gamg->verbose) {
653     if (pc_gamg->verbose==1) ierr =  MatGetInfo(Pmat,MAT_LOCAL,&info);
654     else ierr = MatGetInfo(Pmat,MAT_GLOBAL_SUM,&info);
655     CHKERRQ(ierr);
656     nnz0 = info.nz_used;
657     nnztot = info.nz_used;
658     PetscPrintf(wcomm,"\t[%d]%s level %d N=%d, n data rows=%d, n data cols=%d, nnz/row (ave)=%d, np=%d\n",
659                 mype,__FUNCT__,0,M,pc_gamg->data_cell_rows,pc_gamg->data_cell_cols,
660                 (int)(nnz0/(PetscReal)M),npe);
661   }
662 
663   /* Get A_i and R_i */
664   for ( level=0, Aarr[0]=Pmat, nactivepe = npe; /* hard wired stopping logic */
665         level < (pc_gamg->Nlevels-1) && (level==0 || M>pc_gamg->coarse_eq_limit); /* && (npe==1 || nactivepe>1); */
666         level++ ){
667     level1 = level + 1;
668 #if defined PETSC_GAMG_USE_LOG
669     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET1],0,0,0,0); CHKERRQ(ierr);
670 #if (defined GAMG_STAGES)
671     ierr = PetscLogStagePush(gamg_stages[level]); CHKERRQ( ierr );
672 #endif
673 #endif
674     /* deal with Stokes, get sub matrices */
675     if ( level > 0 ) {
676       ierr = GAMGKKTMatCreate( Aarr[level], stokes, &kktMatsArr[level] ); CHKERRQ(ierr);
677     }
678     { /* construct prolongator */
679       Mat Gmat;
680       PetscCoarsenData *agg_lists;
681       Mat Prol11,Prol22;
682 
683       ierr = pc_gamg->graph( pc,kktMatsArr[level].A11, &Gmat ); CHKERRQ(ierr);
684       ierr = pc_gamg->coarsen( pc, &Gmat, &agg_lists ); CHKERRQ(ierr);
685       ierr = pc_gamg->prolongator( pc, kktMatsArr[level].A11, Gmat, agg_lists, &Prol11 ); CHKERRQ(ierr);
686 
687       /* could have failed to create new level */
688       if ( Prol11 ){
689         /* get new block size of coarse matrices */
690         ierr = MatGetBlockSizes( Prol11, PETSC_NULL, &bs ); CHKERRQ(ierr);
691 
692         if ( stokes ) {
693           if (!pc_gamg->formkktprol) SETERRQ(wcomm,PETSC_ERR_USER,"Stokes not supportd by AMG method.");
694           /* R A12 == (T = A21 P)';  G = T' T; coarsen G; form plain agg with G */
695           ierr = pc_gamg->formkktprol( pc, Prol11, kktMatsArr[level].A21, &Prol22 ); CHKERRQ(ierr);
696         }
697 
698         if ( pc_gamg->optprol ){
699           /* smooth */
700           ierr = pc_gamg->optprol( pc, kktMatsArr[level].A11, &Prol11 ); CHKERRQ(ierr);
701         }
702 
703         if ( stokes ) {
704           IS is_row[2] = {kktMatsArr[level].prim_is,kktMatsArr[level].constr_is};
705           Mat a[4] = {Prol11, PETSC_NULL, PETSC_NULL, Prol22 };
706           ierr = MatCreateNest(wcomm,2,is_row, 2, is_row, a, &Parr[level1] ); CHKERRQ(ierr);
707         }
708         else {
709           Parr[level1] = Prol11;
710         }
711       }
712       else Parr[level1] = PETSC_NULL;
713 
714       if ( pc_gamg->use_aggs_in_gasm ) {
715         ierr = PetscCDGetASMBlocks(agg_lists, bs, &nASMBlocksArr[level], &ASMLocalIDsArr[level] );
716         CHKERRQ(ierr);
717       }
718 
719 
720 
721       ierr = MatDestroy( &Gmat );      CHKERRQ(ierr);
722       ierr = PetscCDDestroy( agg_lists );  CHKERRQ(ierr);
723     } /* construct prolongator scope */
724 #if defined PETSC_GAMG_USE_LOG
725     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET1],0,0,0,0);CHKERRQ(ierr);
726 #endif
727     /* cache eigen estimate */
728     if ( pc_gamg->emax_id != -1 ){
729       PetscBool flag;
730       ierr = PetscObjectComposedDataGetReal( (PetscObject)kktMatsArr[level].A11, pc_gamg->emax_id, emaxs[level], flag );
731       CHKERRQ( ierr );
732       if ( !flag ) emaxs[level] = -1.;
733     }
734     else emaxs[level] = -1.;
735     if (level==0) Aarr[0] = Pmat; /* use Pmat for finest level setup */
736     if ( !Parr[level1] ) {
737       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s stop gridding, level %d\n",mype,__FUNCT__,level);
738       break;
739     }
740 #if defined PETSC_GAMG_USE_LOG
741     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
742 #endif
743 
744     ierr = createLevel( pc, Aarr[level], bs, (PetscBool)(level==pc_gamg->Nlevels-2),
745                         stokes, &Parr[level1], &Aarr[level1], &nactivepe );
746     CHKERRQ(ierr);
747 
748 #if defined PETSC_GAMG_USE_LOG
749     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
750 #endif
751     ierr = MatGetSize( Aarr[level1], &M, &qq );CHKERRQ(ierr);
752 
753     if (pc_gamg->verbose > 0){
754       PetscInt NN = M;
755       if (pc_gamg->verbose==1) {
756         ierr = MatGetInfo(Aarr[level1],MAT_LOCAL,&info); CHKERRQ(ierr);
757         ierr = MatGetLocalSize( Aarr[level1], &NN, &qq );
758       }
759       else ierr = MatGetInfo( Aarr[level1], MAT_GLOBAL_SUM, &info );
760 
761       CHKERRQ(ierr);
762       nnztot += info.nz_used;
763       PetscPrintf(wcomm,"\t\t[%d]%s %d) N=%d, n data cols=%d, nnz/row (ave)=%d, %d active pes\n",
764                   mype,__FUNCT__,(int)level1,M,pc_gamg->data_cell_cols,
765                   (int)(info.nz_used/(PetscReal)NN), nactivepe );
766       CHKERRQ(ierr);
767     }
768 
769     /* stop if one node -- could pull back for singular problems */
770     if ( M/pc_gamg->data_cell_cols < 2 ) {
771       level++;
772       break;
773     }
774 #if (defined PETSC_GAMG_USE_LOG && defined GAMG_STAGES)
775     ierr = PetscLogStagePop(); CHKERRQ( ierr );
776 #endif
777   } /* levels */
778 
779   if ( pc_gamg->data ) {
780     ierr = PetscFree( pc_gamg->data ); CHKERRQ( ierr );
781     pc_gamg->data = PETSC_NULL;
782   }
783 
784   if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s %d levels, grid complexity = %g\n",0,__FUNCT__,level+1,nnztot/nnz0);
785   pc_gamg->Nlevels = level + 1;
786   fine_level = level;
787   ierr = PCMGSetLevels(pc,pc_gamg->Nlevels,PETSC_NULL);CHKERRQ(ierr);
788 
789   /* simple setup */
790   if ( !PETSC_TRUE ){
791     PC_MG_Levels **mglevels = mg->levels;
792     for (lidx=0,level=pc_gamg->Nlevels-1;
793          lidx<fine_level;
794          lidx++, level--){
795       ierr = PCMGSetInterpolation( pc, lidx+1, Parr[level] );CHKERRQ(ierr);
796       ierr = KSPSetOperators( mglevels[lidx]->smoothd, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN );CHKERRQ(ierr);
797       ierr = MatDestroy( &Parr[level] );  CHKERRQ(ierr);
798       ierr = MatDestroy( &Aarr[level] );  CHKERRQ(ierr);
799     }
800     ierr = KSPSetOperators( mglevels[fine_level]->smoothd, Aarr[0], Aarr[0], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
801 
802     ierr = PCSetUp_MG( pc );  CHKERRQ( ierr );
803   }
804   else if ( pc_gamg->Nlevels > 1 ) { /* don't setup MG if one level */
805     /* set default smoothers & set operators */
806     for ( lidx = 1, level = pc_gamg->Nlevels-2;
807           lidx <= fine_level;
808           lidx++, level--) {
809       KSP smoother;
810       PC subpc;
811 
812       ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
813       ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
814 
815       ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
816       /* set ops */
817       ierr = KSPSetOperators( smoother, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
818       ierr = PCMGSetInterpolation( pc, lidx, Parr[level+1] );CHKERRQ(ierr);
819 
820       /* create field split PC, get subsmoother */
821       if ( stokes ) {
822         KSP *ksps;
823         PetscInt nn;
824         ierr = PCFieldSplitSetIS(subpc,"0",kktMatsArr[level].prim_is);   CHKERRQ(ierr);
825         ierr = PCFieldSplitSetIS(subpc,"1",kktMatsArr[level].constr_is); CHKERRQ(ierr);
826         ierr = PCFieldSplitGetSubKSP(subpc,&nn,&ksps); CHKERRQ(ierr);
827         smoother = ksps[0];
828         ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
829         ierr = PetscFree( ksps ); CHKERRQ(ierr);
830       }
831       ierr = GAMGKKTMatDestroy( &kktMatsArr[level] ); CHKERRQ(ierr);
832 
833       /* set defaults */
834       ierr = KSPSetType( smoother, KSPCHEBYSHEV );CHKERRQ(ierr);
835 
836       /* override defaults and command line args (!) */
837       if ( pc_gamg->use_aggs_in_gasm ) {
838         PetscInt sz;
839         IS *is;
840 
841         sz = nASMBlocksArr[level];
842         is = ASMLocalIDsArr[level];
843         ierr = PCSetType( subpc, PCGASM ); CHKERRQ(ierr);
844         if (sz==0){
845           IS is;
846           PetscInt my0,kk;
847           ierr = MatGetOwnershipRange( Aarr[level], &my0, &kk ); CHKERRQ(ierr);
848           ierr = ISCreateGeneral(PETSC_COMM_SELF, 1, &my0, PETSC_COPY_VALUES, &is ); CHKERRQ(ierr);
849           ierr = PCGASMSetSubdomains( subpc, 1, &is, PETSC_NULL ); CHKERRQ(ierr);
850           ierr = ISDestroy( &is ); CHKERRQ(ierr);
851         }
852         else {
853           PetscInt kk;
854           ierr = PCGASMSetSubdomains( subpc, sz, is, PETSC_NULL ); CHKERRQ(ierr);
855           for (kk=0;kk<sz;kk++){
856             ierr = ISDestroy( &is[kk] ); CHKERRQ(ierr);
857           }
858           ierr = PetscFree( is ); CHKERRQ(ierr);
859         }
860         ierr = PCGASMSetOverlap( subpc, 0 ); CHKERRQ(ierr);
861 
862         ASMLocalIDsArr[level] = PETSC_NULL;
863         nASMBlocksArr[level] = 0;
864         ierr = PCGASMSetType( subpc, PC_GASM_BASIC ); CHKERRQ(ierr);
865       }
866       else {
867         ierr = PCSetType( subpc, PCJACOBI ); CHKERRQ(ierr);
868       }
869     }
870     {
871       /* coarse grid */
872       KSP smoother,*k2; PC subpc,pc2; PetscInt ii,first;
873       Mat Lmat = Aarr[(level=pc_gamg->Nlevels-1)]; lidx = 0;
874       ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
875       ierr = KSPSetOperators( smoother, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ(ierr);
876       ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
877       ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
878       ierr = PCSetType( subpc, PCBJACOBI ); CHKERRQ(ierr);
879       ierr = PCSetUp( subpc ); CHKERRQ(ierr);
880       ierr = PCBJacobiGetSubKSP(subpc,&ii,&first,&k2);CHKERRQ(ierr);      assert(ii==1);
881       ierr = KSPGetPC(k2[0],&pc2);CHKERRQ(ierr);
882       ierr = PCSetType( pc2, PCLU ); CHKERRQ(ierr);
883     }
884 
885     /* should be called in PCSetFromOptions_GAMG(), but cannot be called prior to PCMGSetLevels() */
886     ierr = PetscObjectOptionsBegin( (PetscObject)pc );CHKERRQ(ierr);
887     ierr = PCSetFromOptions_MG( pc ); CHKERRQ(ierr);
888     ierr = PetscOptionsEnd();  CHKERRQ(ierr);
889     if (mg->galerkin != 2) SETERRQ(wcomm,PETSC_ERR_USER,"GAMG does Galerkin manually so the -pc_mg_galerkin option must not be used.");
890 
891     /* create cheby smoothers */
892     for ( lidx = 1, level = pc_gamg->Nlevels-2;
893           lidx <= fine_level;
894           lidx++, level--) {
895       KSP smoother;
896       PetscBool flag;
897       PC subpc;
898 
899       ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
900       ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
901 
902       /* create field split PC, get subsmoother */
903       if ( stokes ) {
904         KSP *ksps;
905         PetscInt nn;
906         ierr = PCFieldSplitGetSubKSP(subpc,&nn,&ksps); CHKERRQ(ierr);
907         smoother = ksps[0];
908         ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
909         ierr = PetscFree( ksps );  CHKERRQ(ierr);
910       }
911 
912       /* do my own cheby */
913       ierr = PetscObjectTypeCompare( (PetscObject)smoother, KSPCHEBYSHEV, &flag ); CHKERRQ(ierr);
914       if ( flag ) {
915         PetscReal emax, emin;
916         ierr = PetscObjectTypeCompare( (PetscObject)subpc, PCJACOBI, &flag ); CHKERRQ(ierr);
917         if ( flag && emaxs[level] > 0.0 ) emax=emaxs[level]; /* eigen estimate only for diagnal PC */
918         else{ /* eigen estimate 'emax' */
919           KSP eksp;
920           Mat Lmat = Aarr[level];
921           Vec bb, xx;
922 
923           ierr = MatGetVecs( Lmat, &bb, 0 );         CHKERRQ(ierr);
924           ierr = MatGetVecs( Lmat, &xx, 0 );         CHKERRQ(ierr);
925           {
926             PetscRandom    rctx;
927             ierr = PetscRandomCreate(wcomm,&rctx);CHKERRQ(ierr);
928             ierr = PetscRandomSetFromOptions(rctx);CHKERRQ(ierr);
929             ierr = VecSetRandom(bb,rctx);CHKERRQ(ierr);
930             ierr = PetscRandomDestroy( &rctx ); CHKERRQ(ierr);
931           }
932 
933           /* zeroing out BC rows -- needed for crazy matrices */
934           {
935             PetscInt Istart,Iend,ncols,jj,Ii;
936             PetscScalar zero = 0.0;
937             ierr = MatGetOwnershipRange( Lmat, &Istart, &Iend );    CHKERRQ(ierr);
938             for ( Ii = Istart, jj = 0 ; Ii < Iend ; Ii++, jj++ ) {
939               ierr = MatGetRow(Lmat,Ii,&ncols,0,0); CHKERRQ(ierr);
940               if( ncols <= 1 ) {
941                 ierr = VecSetValues( bb, 1, &Ii, &zero, INSERT_VALUES );  CHKERRQ(ierr);
942               }
943               ierr = MatRestoreRow(Lmat,Ii,&ncols,0,0); CHKERRQ(ierr);
944             }
945             ierr = VecAssemblyBegin(bb); CHKERRQ(ierr);
946             ierr = VecAssemblyEnd(bb); CHKERRQ(ierr);
947           }
948 
949           ierr = KSPCreate( wcomm, &eksp );CHKERRQ(ierr);
950           ierr = KSPSetTolerances( eksp, PETSC_DEFAULT, PETSC_DEFAULT, PETSC_DEFAULT, 10 );
951           CHKERRQ(ierr);
952           ierr = KSPSetNormType( eksp, KSP_NORM_NONE );                 CHKERRQ(ierr);
953           ierr = KSPSetOptionsPrefix(eksp,((PetscObject)pc)->prefix);CHKERRQ(ierr);
954           ierr = KSPAppendOptionsPrefix( eksp, "gamg_est_");         CHKERRQ(ierr);
955           ierr = KSPSetFromOptions( eksp );    CHKERRQ(ierr);
956 
957           ierr = KSPSetInitialGuessNonzero( eksp, PETSC_FALSE ); CHKERRQ(ierr);
958           ierr = KSPSetOperators( eksp, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ( ierr );
959           ierr = KSPSetComputeSingularValues( eksp,PETSC_TRUE ); CHKERRQ(ierr);
960 
961           /* set PC type to be same as smoother */
962           ierr = KSPSetPC( eksp, subpc ); CHKERRQ( ierr );
963 
964           /* solve - keep stuff out of logging */
965           ierr = PetscLogEventDeactivate(KSP_Solve);CHKERRQ(ierr);
966           ierr = PetscLogEventDeactivate(PC_Apply);CHKERRQ(ierr);
967           ierr = KSPSolve( eksp, bb, xx ); CHKERRQ(ierr);
968           ierr = PetscLogEventActivate(KSP_Solve);CHKERRQ(ierr);
969           ierr = PetscLogEventActivate(PC_Apply);CHKERRQ(ierr);
970 
971           ierr = KSPComputeExtremeSingularValues( eksp, &emax, &emin ); CHKERRQ(ierr);
972 
973           ierr = VecDestroy( &xx );       CHKERRQ(ierr);
974           ierr = VecDestroy( &bb );       CHKERRQ(ierr);
975           ierr = KSPDestroy( &eksp );       CHKERRQ(ierr);
976 
977           if ( pc_gamg->verbose > 0 ) {
978             PetscInt N1, tt;
979             ierr = MatGetSize( Aarr[level], &N1, &tt );         CHKERRQ(ierr);
980             PetscPrintf(wcomm,"\t\t\t%s PC setup max eigen=%e min=%e on level %d (N=%d)\n",__FUNCT__,emax,emin,lidx,N1);
981           }
982         }
983         {
984           PetscInt N1, N0;
985           ierr = MatGetSize( Aarr[level], &N1, PETSC_NULL );         CHKERRQ(ierr);
986           ierr = MatGetSize( Aarr[level+1], &N0, PETSC_NULL );       CHKERRQ(ierr);
987           /* heuristic - is this crap? */
988           /* emin = 1.*emax/((PetscReal)N1/(PetscReal)N0); */
989 	  emin = emax * pc_gamg->eigtarget[0];
990           emax *= pc_gamg->eigtarget[1];
991         }
992         ierr = KSPChebyshevSetEigenvalues( smoother, emax, emin );CHKERRQ(ierr);
993       } /* setup checby flag */
994     } /* non-coarse levels */
995 
996     /* clean up */
997     for (level=1;level<pc_gamg->Nlevels;level++){
998       ierr = MatDestroy( &Parr[level] );  CHKERRQ(ierr);
999       ierr = MatDestroy( &Aarr[level] );  CHKERRQ(ierr);
1000     }
1001 
1002     ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
1003 
1004     if ( PETSC_FALSE ){
1005       KSP smoother;  /* PCSetUp_MG seems to insists on setting this to GMRES on coarse grid */
1006       ierr = PCMGGetSmoother( pc, 0, &smoother ); CHKERRQ(ierr);
1007       ierr = KSPSetType( smoother, KSPPREONLY ); CHKERRQ(ierr);
1008     }
1009   }
1010   else {
1011     KSP smoother;
1012     if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s one level solver used (system is seen as DD). Using default solver.\n",mype,__FUNCT__);
1013     ierr = PCMGGetSmoother( pc, 0, &smoother ); CHKERRQ(ierr);
1014     ierr = KSPSetOperators( smoother, Aarr[0], Aarr[0], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
1015     ierr = KSPSetType( smoother, KSPPREONLY ); CHKERRQ(ierr);
1016     ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
1017   }
1018 
1019   PetscFunctionReturn(0);
1020 }
1021 
1022 /* ------------------------------------------------------------------------- */
1023 /*
1024  PCDestroy_GAMG - Destroys the private context for the GAMG preconditioner
1025    that was created with PCCreate_GAMG().
1026 
1027    Input Parameter:
1028 .  pc - the preconditioner context
1029 
1030    Application Interface Routine: PCDestroy()
1031 */
1032 #undef __FUNCT__
1033 #define __FUNCT__ "PCDestroy_GAMG"
1034 PetscErrorCode PCDestroy_GAMG( PC pc )
1035 {
1036   PetscErrorCode  ierr;
1037   PC_MG           *mg = (PC_MG*)pc->data;
1038   PC_GAMG         *pc_gamg= (PC_GAMG*)mg->innerctx;
1039 
1040   PetscFunctionBegin;
1041   ierr = PCReset_GAMG( pc );CHKERRQ(ierr);
1042   ierr = PetscFree( pc_gamg );CHKERRQ(ierr);
1043   ierr = PCDestroy_MG( pc );CHKERRQ(ierr);
1044   PetscFunctionReturn(0);
1045 }
1046 
1047 
1048 #undef __FUNCT__
1049 #define __FUNCT__ "PCGAMGSetProcEqLim"
1050 /*@
1051    PCGAMGSetProcEqLim - Set number of equations to aim for on coarse grids via
1052    processor reduction.
1053 
1054    Not Collective on PC
1055 
1056    Input Parameters:
1057 .  pc - the preconditioner context
1058 
1059 
1060    Options Database Key:
1061 .  -pc_gamg_process_eq_limit
1062 
1063    Level: intermediate
1064 
1065    Concepts: Unstructured multrigrid preconditioner
1066 
1067 .seealso: ()
1068 @*/
1069 PetscErrorCode  PCGAMGSetProcEqLim(PC pc, PetscInt n)
1070 {
1071   PetscErrorCode ierr;
1072 
1073   PetscFunctionBegin;
1074   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1075   ierr = PetscTryMethod(pc,"PCGAMGSetProcEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1076   PetscFunctionReturn(0);
1077 }
1078 
1079 EXTERN_C_BEGIN
1080 #undef __FUNCT__
1081 #define __FUNCT__ "PCGAMGSetProcEqLim_GAMG"
1082 PetscErrorCode PCGAMGSetProcEqLim_GAMG(PC pc, PetscInt n)
1083 {
1084   PC_MG           *mg = (PC_MG*)pc->data;
1085   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1086 
1087   PetscFunctionBegin;
1088   if (n>0) pc_gamg->min_eq_proc = n;
1089   PetscFunctionReturn(0);
1090 }
1091 EXTERN_C_END
1092 
1093 #undef __FUNCT__
1094 #define __FUNCT__ "PCGAMGSetCoarseEqLim"
1095 /*@
1096    PCGAMGSetCoarseEqLim - Set max number of equations on coarse grids.
1097 
1098  Collective on PC
1099 
1100    Input Parameters:
1101 .  pc - the preconditioner context
1102 
1103 
1104    Options Database Key:
1105 .  -pc_gamg_coarse_eq_limit
1106 
1107    Level: intermediate
1108 
1109    Concepts: Unstructured multrigrid preconditioner
1110 
1111 .seealso: ()
1112  @*/
1113 PetscErrorCode PCGAMGSetCoarseEqLim(PC pc, PetscInt n)
1114 {
1115   PetscErrorCode ierr;
1116 
1117   PetscFunctionBegin;
1118   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1119   ierr = PetscTryMethod(pc,"PCGAMGSetCoarseEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1120   PetscFunctionReturn(0);
1121 }
1122 
1123 EXTERN_C_BEGIN
1124 #undef __FUNCT__
1125 #define __FUNCT__ "PCGAMGSetCoarseEqLim_GAMG"
1126 PetscErrorCode PCGAMGSetCoarseEqLim_GAMG(PC pc, PetscInt n)
1127 {
1128   PC_MG           *mg = (PC_MG*)pc->data;
1129   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1130 
1131   PetscFunctionBegin;
1132   if (n>0) pc_gamg->coarse_eq_limit = n;
1133   PetscFunctionReturn(0);
1134 }
1135 EXTERN_C_END
1136 
1137 #undef __FUNCT__
1138 #define __FUNCT__ "PCGAMGSetRepartitioning"
1139 /*@
1140    PCGAMGSetRepartitioning - Repartition the coarse grids
1141 
1142    Collective on PC
1143 
1144    Input Parameters:
1145 .  pc - the preconditioner context
1146 
1147 
1148    Options Database Key:
1149 .  -pc_gamg_repartition
1150 
1151    Level: intermediate
1152 
1153    Concepts: Unstructured multrigrid preconditioner
1154 
1155 .seealso: ()
1156 @*/
1157 PetscErrorCode PCGAMGSetRepartitioning(PC pc, PetscBool n)
1158 {
1159   PetscErrorCode ierr;
1160 
1161   PetscFunctionBegin;
1162   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1163   ierr = PetscTryMethod(pc,"PCGAMGSetRepartitioning_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
1164   PetscFunctionReturn(0);
1165 }
1166 
1167 EXTERN_C_BEGIN
1168 #undef __FUNCT__
1169 #define __FUNCT__ "PCGAMGSetRepartitioning_GAMG"
1170 PetscErrorCode PCGAMGSetRepartitioning_GAMG(PC pc, PetscBool n)
1171 {
1172   PC_MG           *mg = (PC_MG*)pc->data;
1173   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1174 
1175   PetscFunctionBegin;
1176   pc_gamg->repart = n;
1177   PetscFunctionReturn(0);
1178 }
1179 EXTERN_C_END
1180 
1181 #undef __FUNCT__
1182 #define __FUNCT__ "PCGAMGSetUseASMAggs"
1183 /*@
1184    PCGAMGSetUseASMAggs -
1185 
1186    Collective on PC
1187 
1188    Input Parameters:
1189 .  pc - the preconditioner context
1190 
1191 
1192    Options Database Key:
1193 .  -pc_gamg_use_agg_gasm
1194 
1195    Level: intermediate
1196 
1197    Concepts: Unstructured multrigrid preconditioner
1198 
1199 .seealso: ()
1200 @*/
1201 PetscErrorCode PCGAMGSetUseASMAggs(PC pc, PetscBool n)
1202 {
1203   PetscErrorCode ierr;
1204 
1205   PetscFunctionBegin;
1206   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1207   ierr = PetscTryMethod(pc,"PCGAMGSetUseASMAggs_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
1208   PetscFunctionReturn(0);
1209 }
1210 
1211 EXTERN_C_BEGIN
1212 #undef __FUNCT__
1213 #define __FUNCT__ "PCGAMGSetUseASMAggs_GAMG"
1214 PetscErrorCode PCGAMGSetUseASMAggs_GAMG(PC pc, PetscBool n)
1215 {
1216   PC_MG           *mg = (PC_MG*)pc->data;
1217   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1218 
1219   PetscFunctionBegin;
1220   pc_gamg->use_aggs_in_gasm = n;
1221   PetscFunctionReturn(0);
1222 }
1223 EXTERN_C_END
1224 
1225 #undef __FUNCT__
1226 #define __FUNCT__ "PCGAMGSetNlevels"
1227 /*@
1228    PCGAMGSetNlevels -
1229 
1230    Not collective on PC
1231 
1232    Input Parameters:
1233 .  pc - the preconditioner context
1234 
1235 
1236    Options Database Key:
1237 .  -pc_mg_levels
1238 
1239    Level: intermediate
1240 
1241    Concepts: Unstructured multrigrid preconditioner
1242 
1243 .seealso: ()
1244 @*/
1245 PetscErrorCode PCGAMGSetNlevels(PC pc, PetscInt n)
1246 {
1247   PetscErrorCode ierr;
1248 
1249   PetscFunctionBegin;
1250   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1251   ierr = PetscTryMethod(pc,"PCGAMGSetNlevels_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1252   PetscFunctionReturn(0);
1253 }
1254 
1255 EXTERN_C_BEGIN
1256 #undef __FUNCT__
1257 #define __FUNCT__ "PCGAMGSetNlevels_GAMG"
1258 PetscErrorCode PCGAMGSetNlevels_GAMG(PC pc, PetscInt n)
1259 {
1260   PC_MG           *mg = (PC_MG*)pc->data;
1261   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1262 
1263   PetscFunctionBegin;
1264   pc_gamg->Nlevels = n;
1265   PetscFunctionReturn(0);
1266 }
1267 EXTERN_C_END
1268 
1269 #undef __FUNCT__
1270 #define __FUNCT__ "PCGAMGSetThreshold"
1271 /*@
1272    PCGAMGSetThreshold - Relative threshold to use for dropping edges in aggregation graph
1273 
1274    Not collective on PC
1275 
1276    Input Parameters:
1277 .  pc - the preconditioner context
1278 
1279 
1280    Options Database Key:
1281 .  -pc_gamg_threshold
1282 
1283    Level: intermediate
1284 
1285    Concepts: Unstructured multrigrid preconditioner
1286 
1287 .seealso: ()
1288 @*/
1289 PetscErrorCode PCGAMGSetThreshold(PC pc, PetscReal n)
1290 {
1291   PetscErrorCode ierr;
1292 
1293   PetscFunctionBegin;
1294   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1295   ierr = PetscTryMethod(pc,"PCGAMGSetThreshold_C",(PC,PetscReal),(pc,n));CHKERRQ(ierr);
1296   PetscFunctionReturn(0);
1297 }
1298 
1299 EXTERN_C_BEGIN
1300 #undef __FUNCT__
1301 #define __FUNCT__ "PCGAMGSetThreshold_GAMG"
1302 PetscErrorCode PCGAMGSetThreshold_GAMG(PC pc, PetscReal n)
1303 {
1304   PC_MG           *mg = (PC_MG*)pc->data;
1305   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1306 
1307   PetscFunctionBegin;
1308   pc_gamg->threshold = n;
1309   PetscFunctionReturn(0);
1310 }
1311 EXTERN_C_END
1312 
1313 #undef __FUNCT__
1314 #define __FUNCT__ "PCGAMGSetType"
1315 /*@
1316    PCGAMGSetType - Set solution method - calls sub create method
1317 
1318    Collective on PC
1319 
1320    Input Parameters:
1321 .  pc - the preconditioner context
1322 
1323 
1324    Options Database Key:
1325 .  -pc_gamg_type
1326 
1327    Level: intermediate
1328 
1329    Concepts: Unstructured multrigrid preconditioner
1330 
1331 .seealso: ()
1332 @*/
1333 PetscErrorCode PCGAMGSetType( PC pc, PCGAMGType type )
1334 {
1335   PetscErrorCode ierr;
1336 
1337   PetscFunctionBegin;
1338   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1339   ierr = PetscTryMethod(pc,"PCGAMGSetType_C",(PC,PCGAMGType),(pc,type));
1340   CHKERRQ(ierr);
1341   PetscFunctionReturn(0);
1342 }
1343 
1344 EXTERN_C_BEGIN
1345 #undef __FUNCT__
1346 #define __FUNCT__ "PCGAMGSetType_GAMG"
1347 PetscErrorCode PCGAMGSetType_GAMG( PC pc, PCGAMGType type )
1348 {
1349   PetscErrorCode ierr,(*r)(PC);
1350 
1351   PetscFunctionBegin;
1352   ierr = PetscFListFind(GAMGList,((PetscObject)pc)->comm,type,PETSC_FALSE,(PetscVoidStarFunction)&r);
1353   CHKERRQ(ierr);
1354 
1355   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unknown GAMG type %s given",type);
1356 
1357   /* call sub create method */
1358   ierr = (*r)(pc); CHKERRQ(ierr);
1359 
1360   PetscFunctionReturn(0);
1361 }
1362 EXTERN_C_END
1363 
1364 #undef __FUNCT__
1365 #define __FUNCT__ "PCSetFromOptions_GAMG"
1366 PetscErrorCode PCSetFromOptions_GAMG( PC pc )
1367 {
1368   PetscErrorCode  ierr;
1369   PC_MG           *mg = (PC_MG*)pc->data;
1370   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1371   PetscBool        flag;
1372   PetscInt         two = 2;
1373   MPI_Comm         wcomm = ((PetscObject)pc)->comm;
1374 
1375   PetscFunctionBegin;
1376   ierr = PetscOptionsHead("GAMG options"); CHKERRQ(ierr);
1377   {
1378     /* -pc_gamg_verbose */
1379     ierr = PetscOptionsInt("-pc_gamg_verbose","Verbose (debugging) output for PCGAMG",
1380                            "none", pc_gamg->verbose,
1381                            &pc_gamg->verbose, PETSC_NULL );
1382     CHKERRQ(ierr);
1383 
1384     /* -pc_gamg_repartition */
1385     ierr = PetscOptionsBool("-pc_gamg_repartition",
1386                             "Repartion coarse grids (false)",
1387                             "PCGAMGRepartitioning",
1388                             pc_gamg->repart,
1389                             &pc_gamg->repart,
1390                             &flag);
1391     CHKERRQ(ierr);
1392 
1393     /* -pc_gamg_use_agg_gasm */
1394     ierr = PetscOptionsBool("-pc_gamg_use_agg_gasm",
1395                             "Use aggregation agragates for GASM smoother (false)",
1396                             "PCGAMGUseASMAggs",
1397                             pc_gamg->use_aggs_in_gasm,
1398                             &pc_gamg->use_aggs_in_gasm,
1399                             &flag);
1400     CHKERRQ(ierr);
1401 
1402     /* -pc_gamg_process_eq_limit */
1403     ierr = PetscOptionsInt("-pc_gamg_process_eq_limit",
1404                            "Limit (goal) on number of equations per process on coarse grids",
1405                            "PCGAMGSetProcEqLim",
1406                            pc_gamg->min_eq_proc,
1407                            &pc_gamg->min_eq_proc,
1408                            &flag );
1409     CHKERRQ(ierr);
1410 
1411     /* -pc_gamg_coarse_eq_limit */
1412     ierr = PetscOptionsInt("-pc_gamg_coarse_eq_limit",
1413                            "Limit on number of equations for the coarse grid",
1414                            "PCGAMGSetCoarseEqLim",
1415                            pc_gamg->coarse_eq_limit,
1416                            &pc_gamg->coarse_eq_limit,
1417                            &flag );
1418     CHKERRQ(ierr);
1419 
1420     /* -pc_gamg_threshold */
1421     ierr = PetscOptionsReal("-pc_gamg_threshold",
1422                             "Relative threshold to use for dropping edges in aggregation graph",
1423                             "PCGAMGSetThreshold",
1424                             pc_gamg->threshold,
1425                             &pc_gamg->threshold,
1426                             &flag );
1427     CHKERRQ(ierr);
1428     if (flag && pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s threshold set %e\n",0,__FUNCT__,pc_gamg->threshold);
1429 
1430     ierr = PetscOptionsRealArray("-pc_gamg_eigtarget","Target eigenvalue range as fraction of estimated maximum eigenvalue","PCGAMGSetEigTarget",pc_gamg->eigtarget,&two,PETSC_NULL);CHKERRQ(ierr);
1431 
1432     ierr = PetscOptionsInt("-pc_mg_levels",
1433                            "Set number of MG levels",
1434                            "PCGAMGSetNlevels",
1435                            pc_gamg->Nlevels,
1436                            &pc_gamg->Nlevels,
1437                            &flag );
1438   }
1439   ierr = PetscOptionsTail();CHKERRQ(ierr);
1440 
1441   PetscFunctionReturn(0);
1442 }
1443 
1444 /* -------------------------------------------------------------------------- */
1445 /*MC
1446      PCGAMG - Geometric algebraic multigrid (AMG) preconditioning framework.
1447        - This is the entry point to GAMG, registered in pcregis.c
1448 
1449    Options Database Keys:
1450    Multigrid options(inherited)
1451 +  -pc_mg_cycles <1>: 1 for V cycle, 2 for W-cycle (PCMGSetCycleType)
1452 .  -pc_mg_smoothup <1>: Number of post-smoothing steps (PCMGSetNumberSmoothUp)
1453 .  -pc_mg_smoothdown <1>: Number of pre-smoothing steps (PCMGSetNumberSmoothDown)
1454 -  -pc_mg_type <multiplicative>: (one of) additive multiplicative full kascade
1455 
1456   Level: intermediate
1457 
1458   Concepts: multigrid
1459 
1460 .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC, PCMGType,
1461            PCMGSetLevels(), PCMGGetLevels(), PCMGSetType(), PCMGSetCycleType(), PCMGSetNumberSmoothDown(),
1462            PCMGSetNumberSmoothUp(), PCMGGetCoarseSolve(), PCMGSetResidual(), PCMGSetInterpolation(),
1463            PCMGSetRestriction(), PCMGGetSmoother(), PCMGGetSmootherUp(), PCMGGetSmootherDown(),
1464            PCMGSetCyclesOnLevel(), PCMGSetRhs(), PCMGSetX(), PCMGSetR()
1465 M*/
1466 EXTERN_C_BEGIN
1467 #undef __FUNCT__
1468 #define __FUNCT__ "PCCreate_GAMG"
1469 PetscErrorCode  PCCreate_GAMG( PC pc )
1470 {
1471   PetscErrorCode  ierr;
1472   PC_GAMG         *pc_gamg;
1473   PC_MG           *mg;
1474 #if defined PETSC_GAMG_USE_LOG
1475   static long count = 0;
1476 #endif
1477 
1478   PetscFunctionBegin;
1479 
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 = PetscFListAdd(&GAMGList,GAMGGEO,"PCCreateGAMG_GEO",(void(*)(void))PCCreateGAMG_GEO);CHKERRQ(ierr);
1498     ierr = PetscFListAdd(&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);
1511   CHKERRQ(ierr);
1512 
1513   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1514 					    "PCGAMGSetCoarseEqLim_C",
1515 					    "PCGAMGSetCoarseEqLim_GAMG",
1516 					    PCGAMGSetCoarseEqLim_GAMG);
1517   CHKERRQ(ierr);
1518 
1519   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1520 					    "PCGAMGSetRepartitioning_C",
1521 					    "PCGAMGSetRepartitioning_GAMG",
1522 					    PCGAMGSetRepartitioning_GAMG);
1523   CHKERRQ(ierr);
1524 
1525   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1526 					    "PCGAMGSetUseASMAggs_C",
1527 					    "PCGAMGSetUseASMAggs_GAMG",
1528 					    PCGAMGSetUseASMAggs_GAMG);
1529   CHKERRQ(ierr);
1530 
1531   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1532 					    "PCGAMGSetThreshold_C",
1533 					    "PCGAMGSetThreshold_GAMG",
1534 					    PCGAMGSetThreshold_GAMG);
1535   CHKERRQ(ierr);
1536 
1537   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1538 					    "PCGAMGSetType_C",
1539 					    "PCGAMGSetType_GAMG",
1540 					    PCGAMGSetType_GAMG);
1541   CHKERRQ(ierr);
1542 
1543   pc_gamg->repart = PETSC_FALSE;
1544   pc_gamg->use_aggs_in_gasm = PETSC_FALSE;
1545   pc_gamg->min_eq_proc = 100;
1546   pc_gamg->coarse_eq_limit = 800;
1547   pc_gamg->threshold = 0.001;
1548   pc_gamg->Nlevels = GAMG_MAXLEVELS;
1549   pc_gamg->verbose = 0;
1550   pc_gamg->emax_id = -1;
1551   pc_gamg->eigtarget[0] = 0.05;
1552   pc_gamg->eigtarget[1] = 1.05;
1553 
1554   /* private events */
1555 #if defined PETSC_GAMG_USE_LOG
1556   if ( count++ == 0 ) {
1557     PetscLogEventRegister("GAMG: createProl", PC_CLASSID, &petsc_gamg_setup_events[SET1]);
1558     PetscLogEventRegister("  Graph", PC_CLASSID, &petsc_gamg_setup_events[GRAPH]);
1559     /* PetscLogEventRegister("    G.Mat", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_MAT]); */
1560     /* PetscLogEventRegister("    G.Filter", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_FILTER]); */
1561     /* PetscLogEventRegister("    G.Square", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_SQR]); */
1562     PetscLogEventRegister("  MIS/Agg", PC_CLASSID, &petsc_gamg_setup_events[SET4]);
1563     PetscLogEventRegister("  geo: growSupp", PC_CLASSID, &petsc_gamg_setup_events[SET5]);
1564     PetscLogEventRegister("  geo: triangle", PC_CLASSID, &petsc_gamg_setup_events[SET6]);
1565     PetscLogEventRegister("    search&set", PC_CLASSID, &petsc_gamg_setup_events[FIND_V]);
1566     PetscLogEventRegister("  SA: col data", PC_CLASSID, &petsc_gamg_setup_events[SET7]);
1567     PetscLogEventRegister("  SA: frmProl0", PC_CLASSID, &petsc_gamg_setup_events[SET8]);
1568     PetscLogEventRegister("  SA: smooth", PC_CLASSID, &petsc_gamg_setup_events[SET9]);
1569     PetscLogEventRegister("GAMG: partLevel", PC_CLASSID, &petsc_gamg_setup_events[SET2]);
1570     PetscLogEventRegister("  repartition", PC_CLASSID, &petsc_gamg_setup_events[SET12]);
1571     PetscLogEventRegister("  Invert-Sort", PC_CLASSID, &petsc_gamg_setup_events[SET13]);
1572     PetscLogEventRegister("  Move A", PC_CLASSID, &petsc_gamg_setup_events[SET14]);
1573     PetscLogEventRegister("  Move P", PC_CLASSID, &petsc_gamg_setup_events[SET15]);
1574 
1575     /* PetscLogEventRegister(" PL move data", PC_CLASSID, &petsc_gamg_setup_events[SET13]); */
1576     /* PetscLogEventRegister("GAMG: fix", PC_CLASSID, &petsc_gamg_setup_events[SET10]); */
1577     /* PetscLogEventRegister("GAMG: set levels", PC_CLASSID, &petsc_gamg_setup_events[SET11]); */
1578     /* create timer stages */
1579 #if defined GAMG_STAGES
1580     {
1581       char str[32];
1582       sprintf(str,"MG Level %d (finest)",0);
1583       PetscLogStageRegister(str, &gamg_stages[0]);
1584       PetscInt lidx;
1585       for (lidx=1;lidx<9;lidx++){
1586 	sprintf(str,"MG Level %d",lidx);
1587 	PetscLogStageRegister(str, &gamg_stages[lidx]);
1588       }
1589     }
1590 #endif
1591   }
1592 #endif
1593   /* general events */
1594 #if defined PETSC_USE_LOG
1595   PetscLogEventRegister("PCGAMGgraph_AGG", 0, &PC_GAMGGgraph_AGG);
1596   PetscLogEventRegister("PCGAMGgraph_GEO", PC_CLASSID, &PC_GAMGGgraph_GEO);
1597   PetscLogEventRegister("PCGAMGcoarse_AGG", PC_CLASSID, &PC_GAMGCoarsen_AGG);
1598   PetscLogEventRegister("PCGAMGcoarse_GEO", PC_CLASSID, &PC_GAMGCoarsen_GEO);
1599   PetscLogEventRegister("PCGAMGProl_AGG", PC_CLASSID, &PC_GAMGProlongator_AGG);
1600   PetscLogEventRegister("PCGAMGProl_GEO", PC_CLASSID, &PC_GAMGProlongator_GEO);
1601   PetscLogEventRegister("PCGAMGPOpt_AGG", PC_CLASSID, &PC_GAMGOptprol_AGG);
1602   PetscLogEventRegister("GAMGKKTProl_AGG", PC_CLASSID, &PC_GAMGKKTProl_AGG);
1603 #endif
1604 
1605   /* instantiate derived type */
1606   ierr = PetscOptionsHead("GAMG options"); CHKERRQ(ierr);
1607   {
1608     char tname[256] = GAMGAGG;
1609     ierr = PetscOptionsList("-pc_gamg_type","Type of GAMG method","PCGAMGSetType",
1610                             GAMGList, tname, tname, sizeof(tname), PETSC_NULL );
1611     CHKERRQ(ierr);
1612     ierr = PCGAMGSetType( pc, tname ); CHKERRQ(ierr);
1613   }
1614   ierr = PetscOptionsTail();   CHKERRQ(ierr);
1615 
1616   PetscFunctionReturn(0);
1617 }
1618 EXTERN_C_END
1619