xref: /petsc/src/ksp/pc/impls/gamg/gamg.c (revision e93c322d3f1dc90bbe56757b7dfbbdeffd9bb884)
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     ierr = PetscFree( pc_gamg->data ); CHKERRQ(ierr);
44   }
45   pc_gamg->data = PETSC_NULL; pc_gamg->data_sz = 0;
46   PetscFunctionReturn(0);
47 }
48 
49 /* private 2x2 Mat Nest for Stokes */
50 typedef struct{
51   Mat A11,A21,A12,Amat;
52   IS  prim_is,constr_is;
53 }GAMGKKTMat;
54 
55 #undef __FUNCT__
56 #define __FUNCT__ "GAMGKKTMatCreate"
57 static PetscErrorCode GAMGKKTMatCreate( Mat A, PetscBool iskkt, GAMGKKTMat *out )
58 {
59   PetscFunctionBegin;
60   out->Amat = A;
61   if( iskkt ){
62     PetscErrorCode   ierr;
63     IS       is_constraint, is_prime;
64     PetscInt nmin,nmax;
65 
66     ierr = MatGetOwnershipRange( A, &nmin, &nmax );   CHKERRQ(ierr);
67     ierr = MatFindZeroDiagonals( A, &is_constraint ); CHKERRQ(ierr);
68     ierr = ISComplement( is_constraint, nmin, nmax, &is_prime ); CHKERRQ(ierr);
69     out->prim_is = is_prime;
70     out->constr_is = is_constraint;
71 
72     ierr = MatGetSubMatrix( A, is_prime, is_prime,      MAT_INITIAL_MATRIX, &out->A11); CHKERRQ(ierr);
73     ierr = MatGetSubMatrix( A, is_prime, is_constraint, MAT_INITIAL_MATRIX, &out->A12); CHKERRQ(ierr);
74     ierr = MatGetSubMatrix( A, is_constraint, is_prime, MAT_INITIAL_MATRIX, &out->A21); CHKERRQ(ierr);
75 PetscPrintf(((PetscObject)A)->comm,"[%d]%s N=%d N_11=%d\n",0,__FUNCT__,A->rmap->N,out->A11->rmap->N);
76   }
77   else {
78     out->A11 = A;
79     out->A21 = PETSC_NULL;
80     out->A12 = PETSC_NULL;
81     out->prim_is = PETSC_NULL;
82     out->constr_is = PETSC_NULL;
83   }
84   PetscFunctionReturn(0);
85 }
86 
87 #undef __FUNCT__
88 #define __FUNCT__ "GAMGKKTMatDestroy"
89 static PetscErrorCode GAMGKKTMatDestroy( GAMGKKTMat *mat )
90 {
91   PetscErrorCode   ierr;
92 
93   PetscFunctionBegin;
94   if( mat->A11 && mat->A11 != mat->Amat ) {
95     ierr = MatDestroy( &mat->A11 );  CHKERRQ(ierr);
96   }
97   ierr = MatDestroy( &mat->A21 );  CHKERRQ(ierr);
98   ierr = MatDestroy( &mat->A12 );  CHKERRQ(ierr);
99 
100   ierr = ISDestroy( &mat->prim_is );    CHKERRQ(ierr);
101   ierr = ISDestroy( &mat->constr_is );    CHKERRQ(ierr);
102 
103   PetscFunctionReturn(0);
104 }
105 
106 /* -------------------------------------------------------------------------- */
107 /*
108    createLevel: create coarse op with RAP.  repartition and/or reduce number
109      of active processors.
110 
111    Input Parameter:
112    . pc - parameters + side effect: coarse data in 'pc_gamg->data' and
113           'pc_gamg->data_sz' are changed via repartitioning/reduction.
114    . Amat_fine - matrix on this fine (k) level
115    . cbs - coarse block size
116    . isLast -
117    . stokes -
118    In/Output Parameter:
119    . a_P_inout - prolongation operator to the next level (k-->k-1)
120    . a_nactive_proc - number of active procs
121    Output Parameter:
122    . a_Amat_crs - coarse matrix that is created (k-1)
123 */
124 
125 #undef __FUNCT__
126 #define __FUNCT__ "createLevel"
127 static PetscErrorCode createLevel( const PC pc,
128                                    const Mat Amat_fine,
129                                    const PetscInt cbs,
130                                    const PetscBool isLast,
131                                    const PetscBool stokes,
132                                    Mat *a_P_inout,
133                                    Mat *a_Amat_crs,
134                                    PetscMPIInt *a_nactive_proc
135                                    )
136 {
137   PetscErrorCode   ierr;
138   PC_MG           *mg = (PC_MG*)pc->data;
139   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
140   const PetscBool  repart = pc_gamg->repart;
141   const PetscInt   min_eq_proc = pc_gamg->min_eq_proc, coarse_max = pc_gamg->coarse_eq_limit;
142   Mat              Cmat,Pold=*a_P_inout;
143   MPI_Comm         wcomm = ((PetscObject)Amat_fine)->comm;
144   PetscMPIInt      mype,npe,new_npe,nactive=*a_nactive_proc;
145   PetscInt         ncrs_eq,ncrs_prim;
146 
147   PetscFunctionBegin;
148   ierr = MPI_Comm_rank( wcomm, &mype ); CHKERRQ(ierr);
149   ierr = MPI_Comm_size( wcomm, &npe );  CHKERRQ(ierr);
150   /* RAP */
151   ierr = MatPtAP( Amat_fine, Pold, MAT_INITIAL_MATRIX, 2.0, &Cmat ); CHKERRQ(ierr);
152 
153   /* set 'ncrs_prim' (nodes), 'ncrs_eq' (equations)*/
154   ncrs_prim = pc_gamg->data_sz/pc_gamg->data_cell_cols/pc_gamg->data_cell_rows;
155   assert(pc_gamg->data_sz%(pc_gamg->data_cell_cols*pc_gamg->data_cell_rows)==0);
156   ierr = MatGetLocalSize( Cmat, &ncrs_eq, PETSC_NULL );  CHKERRQ(ierr);
157 
158   /* get number of PEs to make active 'new_npe', reduce, can be any integer 1-P */
159   {
160     PetscInt ncrs_eq_glob,ncrs_eq_ave;
161     ierr = MatGetSize( Cmat, &ncrs_eq_glob, PETSC_NULL );  CHKERRQ(ierr);
162     ncrs_eq_ave = ncrs_eq_glob/npe;
163     new_npe = (PetscMPIInt)((float)ncrs_eq_ave/(float)min_eq_proc + 0.5); /* hardwire min. number of eq/proc */
164     if( new_npe == 0 || ncrs_eq_ave < coarse_max ) new_npe = 1;
165     else if ( new_npe >= nactive ) new_npe = nactive; /* no change, rare */
166     if( isLast ) new_npe = 1;
167   }
168 
169   if( !repart && new_npe==nactive ) {
170     *a_Amat_crs = Cmat; /* output - no repartitioning or reduction - could bail here */
171     }
172   else {
173     const PetscInt *idx,ndata_rows=pc_gamg->data_cell_rows,ndata_cols=pc_gamg->data_cell_cols,node_data_sz=ndata_rows*ndata_cols;
174     PetscInt       *counts,*newproc_idx,ii,jj,kk,strideNew,*tidx,ncrs_prim_new,ncrs_eq_new,nloc_old;
175     IS              is_eq_newproc,is_eq_newproc_prim,is_eq_num,is_eq_num_prim,isscat,new_eq_indices;
176     VecScatter      vecscat;
177     PetscScalar    *array;
178     Vec             src_crd, dest_crd;
179 
180     nloc_old = ncrs_eq/cbs; assert(ncrs_eq%cbs==0);
181 #if defined PETSC_GAMG_USE_LOG
182     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET12],0,0,0,0);CHKERRQ(ierr);
183 #endif
184     /* make 'is_eq_newproc' */
185     ierr = PetscMalloc( npe*sizeof(PetscInt), &counts ); CHKERRQ(ierr);
186     if( repart && !stokes ) {
187       /* Repartition Cmat_{k} and move colums of P^{k}_{k-1} and coordinates of primal part accordingly */
188       Mat             adj;
189 
190       if (pc_gamg->verbose>0) {
191         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);
192         else {
193           PetscInt n;
194           ierr = MPI_Allreduce( &ncrs_eq, &n, 1, MPIU_INT, MPI_SUM, wcomm );CHKERRQ(ierr);
195           PetscPrintf(wcomm,"\t[%d]%s repartition: npe (active): %d --> %d, neq = %d\n",mype,__FUNCT__,*a_nactive_proc,new_npe,n);
196         }
197       }
198 
199       /* get 'adj' */
200       if( cbs == 1 ) {
201 	ierr = MatConvert( Cmat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
202       }
203       else{
204 	/* make a scalar matrix to partition (no Stokes here) */
205 	Mat tMat;
206 	PetscInt Istart_crs,Iend_crs,ncols,jj,Ii;
207 	const PetscScalar *vals;
208 	const PetscInt *idx;
209 	PetscInt *d_nnz, *o_nnz, M, N;
210 	static PetscInt llev = 0;
211 
212 	ierr = PetscMalloc( ncrs_prim*sizeof(PetscInt), &d_nnz ); CHKERRQ(ierr);
213 	ierr = PetscMalloc( ncrs_prim*sizeof(PetscInt), &o_nnz ); CHKERRQ(ierr);
214         ierr = MatGetOwnershipRange( Cmat, &Istart_crs, &Iend_crs );    CHKERRQ(ierr);
215         ierr = MatGetSize( Cmat, &M, &N );CHKERRQ(ierr);
216 	for ( Ii = Istart_crs, jj = 0 ; Ii < Iend_crs ; Ii += cbs, jj++ ) {
217 	  ierr = MatGetRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
218 	  d_nnz[jj] = ncols/cbs;
219 	  o_nnz[jj] = ncols/cbs;
220 	  ierr = MatRestoreRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
221 	  if( d_nnz[jj] > ncrs_prim ) d_nnz[jj] = ncrs_prim;
222 	  if( o_nnz[jj] > (M/cbs-ncrs_prim) ) o_nnz[jj] = M/cbs-ncrs_prim;
223 	}
224 
225 	ierr = MatCreate( wcomm, &tMat ); CHKERRQ(ierr);
226 	ierr = MatSetSizes( tMat, ncrs_prim, ncrs_prim,
227                             PETSC_DETERMINE, PETSC_DETERMINE );
228         CHKERRQ(ierr);
229         ierr = MatSetType(tMat,MATAIJ);   CHKERRQ(ierr);
230         ierr = MatSeqAIJSetPreallocation(tMat,0,d_nnz);CHKERRQ(ierr);
231         ierr = MatMPIAIJSetPreallocation(tMat,0,d_nnz,0,o_nnz);CHKERRQ(ierr);
232 	ierr = PetscFree( d_nnz ); CHKERRQ(ierr);
233 	ierr = PetscFree( o_nnz ); CHKERRQ(ierr);
234 
235 	for ( ii = Istart_crs; ii < Iend_crs; ii++ ) {
236 	  PetscInt dest_row = ii/cbs;
237 	  ierr = MatGetRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
238 	  for( jj = 0 ; jj < ncols ; jj++ ){
239 	    PetscInt dest_col = idx[jj]/cbs;
240 	    PetscScalar v = 1.0;
241 	    ierr = MatSetValues(tMat,1,&dest_row,1,&dest_col,&v,ADD_VALUES); CHKERRQ(ierr);
242 	  }
243 	  ierr = MatRestoreRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
244 	}
245 	ierr = MatAssemblyBegin(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
246 	ierr = MatAssemblyEnd(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
247 
248 	if( llev++ == -1 ) {
249 	  PetscViewer viewer; char fname[32];
250 	  ierr = PetscSNPrintf(fname,sizeof fname,"part_mat_%D.mat",llev);CHKERRQ(ierr);
251 	  PetscViewerBinaryOpen(wcomm,fname,FILE_MODE_WRITE,&viewer);
252 	  ierr = MatView( tMat, viewer ); CHKERRQ(ierr);
253 	  ierr = PetscViewerDestroy( &viewer );
254 	}
255 
256 	ierr = MatConvert( tMat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
257 
258 	ierr = MatDestroy( &tMat );  CHKERRQ(ierr);
259       } /* create 'adj' */
260 
261       { /* partition: get newproc_idx */
262 	char prefix[256];
263 	const char *pcpre;
264 	const PetscInt *is_idx;
265 	MatPartitioning  mpart;
266 	IS proc_is;
267 	PetscInt targetPE;
268 
269 	ierr = MatPartitioningCreate( wcomm, &mpart ); CHKERRQ(ierr);
270 	ierr = MatPartitioningSetAdjacency( mpart, adj ); CHKERRQ(ierr);
271 	ierr = PCGetOptionsPrefix( pc, &pcpre );CHKERRQ(ierr);
272 	ierr = PetscSNPrintf(prefix,sizeof prefix,"%spc_gamg_",pcpre?pcpre:"");CHKERRQ(ierr);
273 	ierr = PetscObjectSetOptionsPrefix((PetscObject)mpart,prefix);CHKERRQ(ierr);
274 	ierr = MatPartitioningSetFromOptions( mpart );    CHKERRQ(ierr);
275 	ierr = MatPartitioningSetNParts( mpart, new_npe );CHKERRQ(ierr);
276 	ierr = MatPartitioningApply( mpart, &proc_is ); CHKERRQ(ierr);
277 	ierr = MatPartitioningDestroy( &mpart );          CHKERRQ(ierr);
278 
279 	/* collect IS info */
280 	ierr = PetscMalloc( ncrs_eq*sizeof(PetscInt), &newproc_idx ); CHKERRQ(ierr);
281 	ierr = ISGetIndices( proc_is, &is_idx );        CHKERRQ(ierr);
282 	targetPE = 1; /* bring to "front" of machine */
283 	/*targetPE = npe/new_npe;*/ /* spread partitioning across machine */
284 	for( kk = jj = 0 ; kk < nloc_old ; kk++ ){
285 	  for( ii = 0 ; ii < cbs ; ii++, jj++ ){
286 	    newproc_idx[jj] = is_idx[kk] * targetPE; /* distribution */
287 	  }
288 	}
289 	ierr = ISRestoreIndices( proc_is, &is_idx );     CHKERRQ(ierr);
290 	ierr = ISDestroy( &proc_is );                    CHKERRQ(ierr);
291       }
292       ierr = MatDestroy( &adj );                       CHKERRQ(ierr);
293 
294       ierr = ISCreateGeneral( wcomm, ncrs_eq, newproc_idx, PETSC_COPY_VALUES, &is_eq_newproc );
295       CHKERRQ(ierr);
296       if( newproc_idx != 0 ) {
297 	ierr = PetscFree( newproc_idx );  CHKERRQ(ierr);
298       }
299     } /* repartitioning */
300     else { /* simple aggreagtion of parts -- 'is_eq_newproc' */
301 
302       PetscInt rfactor,targetPE;
303       /* find factor */
304       if( new_npe == 1 ) rfactor = npe; /* easy */
305       else {
306 	PetscReal best_fact = 0.;
307 	jj = -1;
308 	for( kk = 1 ; kk <= npe ; kk++ ){
309 	  if( npe%kk==0 ) { /* a candidate */
310 	    PetscReal nactpe = (PetscReal)npe/(PetscReal)kk, fact = nactpe/(PetscReal)new_npe;
311 	    if(fact > 1.0) fact = 1./fact; /* keep fact < 1 */
312 	    if( fact > best_fact ) {
313 	      best_fact = fact; jj = kk;
314 	    }
315 	  }
316 	}
317 	if( jj != -1 ) rfactor = jj;
318 	else rfactor = 1; /* does this happen .. a prime */
319       }
320       new_npe = npe/rfactor;
321 
322       if( new_npe==nactive ) {
323 	*a_Amat_crs = Cmat; /* output - no repartitioning or reduction, bail out because nested here */
324 	ierr = PetscFree( counts );  CHKERRQ(ierr);
325 	if (pc_gamg->verbose>0){
326           PetscPrintf(wcomm,"\t[%d]%s aggregate processors noop: new_npe=%d, neq(loc)=%d\n",mype,__FUNCT__,new_npe,ncrs_eq);
327         }
328 	PetscFunctionReturn(0);
329       }
330 
331       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s number of equations (loc) %d with simple aggregation\n",mype,__FUNCT__,ncrs_eq);
332       targetPE = mype/rfactor;
333       ierr = ISCreateStride( wcomm, ncrs_eq, targetPE, 0, &is_eq_newproc ); CHKERRQ(ierr);
334 
335       if( stokes ) {
336         ierr = ISCreateStride( wcomm, ncrs_prim*cbs, targetPE, 0, &is_eq_newproc_prim ); CHKERRQ(ierr);
337       }
338     } /* end simple 'is_eq_newproc' */
339 
340     /*
341      Create an index set from the is_eq_newproc index set to indicate the mapping TO
342      */
343     ierr = ISPartitioningToNumbering( is_eq_newproc, &is_eq_num ); CHKERRQ(ierr);
344     if( stokes ) {
345       ierr = ISPartitioningToNumbering( is_eq_newproc_prim, &is_eq_num_prim ); CHKERRQ(ierr);
346     }
347     else is_eq_num_prim = is_eq_num;
348     /*
349       Determine how many equations/vertices are assigned to each processor
350      */
351     ierr = ISPartitioningCount( is_eq_newproc, npe, counts ); CHKERRQ(ierr);
352     ncrs_eq_new = counts[mype];
353     ierr = ISDestroy( &is_eq_newproc );                       CHKERRQ(ierr);
354     if( stokes ) {
355       ierr = ISPartitioningCount( is_eq_newproc_prim, npe, counts ); CHKERRQ(ierr);
356       ierr = ISDestroy( &is_eq_newproc_prim );                       CHKERRQ(ierr);
357       ncrs_prim_new = counts[mype]/cbs; /* nodes */
358     }
359     else ncrs_prim_new = ncrs_eq_new/cbs; /* eqs */
360 
361     ierr = PetscFree( counts );  CHKERRQ(ierr);
362 #if defined PETSC_GAMG_USE_LOG
363     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET12],0,0,0,0);   CHKERRQ(ierr);
364 #endif
365 
366     /* move data (for primal equations only) */
367     /* Create a vector to contain the newly ordered element information */
368     ierr = VecCreate( wcomm, &dest_crd );
369     ierr = VecSetSizes( dest_crd, node_data_sz*ncrs_prim_new, PETSC_DECIDE ); CHKERRQ(ierr);
370     ierr = VecSetFromOptions( dest_crd ); CHKERRQ(ierr); /* this is needed! */
371     /*
372      There are 'ndata_rows*ndata_cols' data items per node, (one can think of the vectors of having
373      a block size of ...).  Note, ISs are expanded into equation space by 'cbs'.
374      */
375     ierr = PetscMalloc( (ncrs_prim*node_data_sz)*sizeof(PetscInt), &tidx ); CHKERRQ(ierr);
376     ierr = ISGetIndices( is_eq_num_prim, &idx ); CHKERRQ(ierr);
377     for(ii=0,jj=0; ii<ncrs_prim ; ii++) {
378       PetscInt id = idx[ii*cbs]/cbs; /* get node back */
379       for( kk=0; kk<node_data_sz ; kk++, jj++) tidx[jj] = id*node_data_sz + kk;
380     }
381     ierr = ISRestoreIndices( is_eq_num_prim, &idx ); CHKERRQ(ierr);
382     ierr = ISCreateGeneral( wcomm, node_data_sz*ncrs_prim, tidx, PETSC_COPY_VALUES, &isscat );
383     CHKERRQ(ierr);
384     ierr = PetscFree( tidx );  CHKERRQ(ierr);
385     /*
386      Create a vector to contain the original vertex information for each element
387      */
388     ierr = VecCreateSeq( PETSC_COMM_SELF, node_data_sz*ncrs_prim, &src_crd ); CHKERRQ(ierr);
389     for( jj=0; jj<ndata_cols ; jj++ ) {
390       const PetscInt stride0=ncrs_prim*pc_gamg->data_cell_rows;
391       for( ii=0 ; ii<ncrs_prim ; ii++) {
392 	for( kk=0; kk<ndata_rows ; kk++ ) {
393 	  PetscInt ix = ii*ndata_rows + kk + jj*stride0, jx = ii*node_data_sz + kk*ndata_cols + jj;
394           PetscScalar tt = (PetscScalar)pc_gamg->data[ix];
395 	  ierr = VecSetValues( src_crd, 1, &jx, &tt, INSERT_VALUES );  CHKERRQ(ierr);
396 	}
397       }
398     }
399     ierr = VecAssemblyBegin(src_crd); CHKERRQ(ierr);
400     ierr = VecAssemblyEnd(src_crd); CHKERRQ(ierr);
401     /*
402       Scatter the element vertex information (still in the original vertex ordering)
403       to the correct processor
404     */
405     ierr = VecScatterCreate( src_crd, PETSC_NULL, dest_crd, isscat, &vecscat);
406     CHKERRQ(ierr);
407     ierr = ISDestroy( &isscat );       CHKERRQ(ierr);
408     ierr = VecScatterBegin(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
409     ierr = VecScatterEnd(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
410     ierr = VecScatterDestroy( &vecscat );       CHKERRQ(ierr);
411     ierr = VecDestroy( &src_crd );       CHKERRQ(ierr);
412     /*
413       Put the element vertex data into a new allocation of the gdata->ele
414     */
415     ierr = PetscFree( pc_gamg->data );    CHKERRQ(ierr);
416     ierr = PetscMalloc( node_data_sz*ncrs_prim_new*sizeof(PetscReal), &pc_gamg->data );    CHKERRQ(ierr);
417     pc_gamg->data_sz = node_data_sz*ncrs_prim_new;
418     strideNew = ncrs_prim_new*ndata_rows;
419     ierr = VecGetArray( dest_crd, &array );    CHKERRQ(ierr);
420     for( jj=0; jj<ndata_cols ; jj++ ) {
421       for( ii=0 ; ii<ncrs_prim_new ; ii++) {
422 	for( kk=0; kk<ndata_rows ; kk++ ) {
423 	  PetscInt ix = ii*ndata_rows + kk + jj*strideNew, jx = ii*node_data_sz + kk*ndata_cols + jj;
424 	  pc_gamg->data[ix] = PetscRealPart(array[jx]);
425 	}
426       }
427     }
428     ierr = VecRestoreArray( dest_crd, &array );    CHKERRQ(ierr);
429     ierr = VecDestroy( &dest_crd );    CHKERRQ(ierr);
430 
431     /* move A and P (columns) with new layout */
432 #if defined PETSC_GAMG_USE_LOG
433     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
434 #endif
435 
436     /*
437       Invert for MatGetSubMatrix
438     */
439     ierr = ISInvertPermutation( is_eq_num, ncrs_eq_new, &new_eq_indices ); CHKERRQ(ierr);
440     ierr = ISSort( new_eq_indices ); CHKERRQ(ierr); /* is this needed? */
441     if(is_eq_num != is_eq_num_prim) {
442       ierr = ISDestroy( &is_eq_num_prim ); CHKERRQ(ierr); /* could be same as 'is_eq_num' */
443     }
444     ierr = ISDestroy( &is_eq_num ); CHKERRQ(ierr);
445 #if defined PETSC_GAMG_USE_LOG
446     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
447     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
448 #endif
449     /* 'a_Amat_crs' output */
450     {
451       Mat mat;
452       ierr = MatGetSubMatrix( Cmat, new_eq_indices, new_eq_indices, MAT_INITIAL_MATRIX, &mat );
453       CHKERRQ(ierr);
454       *a_Amat_crs = mat;
455     }
456     ierr = MatDestroy( &Cmat ); CHKERRQ(ierr);
457 
458 #if defined PETSC_GAMG_USE_LOG
459     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
460 #endif
461     /* prolongator */
462     {
463       IS findices;
464       PetscInt Istart,Iend;
465       Mat Pnew;
466       ierr = MatGetOwnershipRange( Pold, &Istart, &Iend );    CHKERRQ(ierr);
467 #if defined PETSC_GAMG_USE_LOG
468       ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
469 #endif
470       ierr = ISCreateStride(wcomm,Iend-Istart,Istart,1,&findices);   CHKERRQ(ierr);
471       ierr = MatGetSubMatrix( Pold, findices, new_eq_indices, MAT_INITIAL_MATRIX, &Pnew );
472       CHKERRQ(ierr);
473       ierr = ISDestroy( &findices ); CHKERRQ(ierr);
474 #if defined PETSC_GAMG_USE_LOG
475       ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
476 #endif
477       ierr = MatDestroy( a_P_inout ); CHKERRQ(ierr);
478 
479       /* output - repartitioned */
480       *a_P_inout = Pnew;
481     }
482     ierr = ISDestroy( &new_eq_indices ); CHKERRQ(ierr);
483 
484     *a_nactive_proc = new_npe; /* output */
485   }
486 
487   /* outout matrix data */
488   if( !PETSC_TRUE ) {
489     PetscViewer viewer; char fname[32]; static int llev=0; Cmat = *a_Amat_crs;
490     if(llev==0) {
491       sprintf(fname,"Cmat_%d.m",llev++);
492       PetscViewerASCIIOpen(wcomm,fname,&viewer);
493       ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
494       ierr = MatView(Amat_fine, viewer ); CHKERRQ(ierr);
495       ierr = PetscViewerDestroy( &viewer );
496     }
497     sprintf(fname,"Cmat_%d.m",llev++);
498     PetscViewerASCIIOpen(wcomm,fname,&viewer);
499     ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
500     ierr = MatView(Cmat, viewer ); CHKERRQ(ierr);
501     ierr = PetscViewerDestroy( &viewer );
502   }
503 
504   PetscFunctionReturn(0);
505 }
506 
507 /* -------------------------------------------------------------------------- */
508 /*
509    PCSetUp_GAMG - Prepares for the use of the GAMG preconditioner
510                     by setting data structures and options.
511 
512    Input Parameter:
513 .  pc - the preconditioner context
514 
515    Application Interface Routine: PCSetUp()
516 
517    Notes:
518    The interface routine PCSetUp() is not usually called directly by
519    the user, but instead is called by PCApply() if necessary.
520 */
521 #undef __FUNCT__
522 #define __FUNCT__ "PCSetUp_GAMG"
523 PetscErrorCode PCSetUp_GAMG( PC pc )
524 {
525   PetscErrorCode  ierr;
526   PC_MG           *mg = (PC_MG*)pc->data;
527   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
528   Mat              Pmat = pc->pmat;
529   PetscInt         fine_level,level,level1,bs,M,qq,lidx,nASMBlocksArr[GAMG_MAXLEVELS];
530   MPI_Comm         wcomm = ((PetscObject)pc)->comm;
531   PetscMPIInt      mype,npe,nactivepe;
532   Mat              Aarr[GAMG_MAXLEVELS],Parr[GAMG_MAXLEVELS];
533   PetscReal        emaxs[GAMG_MAXLEVELS];
534   IS              *ASMLocalIDsArr[GAMG_MAXLEVELS],removedEqs[GAMG_MAXLEVELS];
535   PetscInt         level_bs[GAMG_MAXLEVELS];
536   GAMGKKTMat       kktMatsArr[GAMG_MAXLEVELS];
537   PetscLogDouble   nnz0=0.,nnztot=0.;
538   MatInfo          info;
539   PetscBool        stokes = PETSC_FALSE;
540 
541   PetscFunctionBegin;
542   ierr = MPI_Comm_rank(wcomm,&mype);CHKERRQ(ierr);
543   ierr = MPI_Comm_size(wcomm,&npe);CHKERRQ(ierr);
544   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);
545   if( pc_gamg->setup_count++ > 0 ) {
546     PC_MG_Levels **mglevels = mg->levels;
547     /* just do Galerkin grids */
548     Mat B,dA,dB;
549     assert(pc->setupcalled);
550 
551     if( pc_gamg->Nlevels > 1 ) {
552       /* currently only handle case where mat and pmat are the same on coarser levels */
553       ierr = KSPGetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,&dA,&dB,PETSC_NULL);CHKERRQ(ierr);
554       /* (re)set to get dirty flag */
555       ierr = KSPSetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,dA,dB,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
556 
557       for (level=pc_gamg->Nlevels-2; level>-1; level--) {
558         /* the first time through the matrix structure has changed from repartitioning */
559         if( pc_gamg->setup_count==2 /*&& (pc_gamg->repart || level==0)*/) {
560           ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_INITIAL_MATRIX,1.0,&B);CHKERRQ(ierr);
561           ierr = MatDestroy(&mglevels[level]->A);CHKERRQ(ierr);
562           mglevels[level]->A = B;
563         }
564         else {
565           ierr = KSPGetOperators(mglevels[level]->smoothd,PETSC_NULL,&B,PETSC_NULL);CHKERRQ(ierr);
566           ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_REUSE_MATRIX,1.0,&B);CHKERRQ(ierr);
567         }
568         ierr = KSPSetOperators(mglevels[level]->smoothd,B,B,SAME_NONZERO_PATTERN); CHKERRQ(ierr);
569         dB = B;
570       }
571     }
572 
573     ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
574 
575     /* PCSetUp_MG seems to insists on setting this to GMRES */
576     ierr = KSPSetType( mglevels[0]->smoothd, KSPPREONLY ); CHKERRQ(ierr);
577 
578     PetscFunctionReturn(0);
579   }
580   assert(pc->setupcalled == 0);
581 
582   ierr = PetscOptionsGetBool(((PetscObject)pc)->prefix,"-pc_fieldsplit_detect_saddle_point",&stokes,PETSC_NULL);CHKERRQ(ierr);
583 
584   ierr = GAMGKKTMatCreate( Pmat, stokes, &kktMatsArr[0] ); CHKERRQ(ierr);
585 
586   if( pc_gamg->data == 0 ) {
587     if( !pc_gamg->createdefaultdata ){
588       SETERRQ(wcomm,PETSC_ERR_LIB,"'createdefaultdata' not set(?) need to support NULL data");
589     }
590     if( stokes ) {
591       SETERRQ(wcomm,PETSC_ERR_LIB,"Need data (eg, PCSetCoordinates) for Stokes problems");
592     }
593     ierr = pc_gamg->createdefaultdata( pc, kktMatsArr[0].A11 ); CHKERRQ(ierr);
594   }
595 
596   /* get basic dims */
597   if( stokes ) {
598     bs = pc_gamg->data_cell_rows; /* this is agg-mg specific */
599   }
600   else {
601     ierr = MatGetBlockSize( Pmat, &bs ); CHKERRQ(ierr);
602   }
603 
604   ierr = MatGetSize( Pmat, &M, &qq );CHKERRQ(ierr);
605   if (pc_gamg->verbose) {
606     if(pc_gamg->verbose==1) ierr =  MatGetInfo(Pmat,MAT_LOCAL,&info);
607     else ierr = MatGetInfo(Pmat,MAT_GLOBAL_SUM,&info);
608     CHKERRQ(ierr);
609     nnz0 = info.nz_used;
610     nnztot = info.nz_used;
611     PetscPrintf(wcomm,"\t[%d]%s level %d N=%d, n data rows=%d, n data cols=%d, nnz/row (ave)=%d, np=%d\n",
612                 mype,__FUNCT__,0,M,pc_gamg->data_cell_rows,pc_gamg->data_cell_cols,
613                 (int)(nnz0/(PetscReal)M),npe);
614   }
615 
616   /* Get A_i and R_i */
617   for ( level=0, Aarr[0]=Pmat, nactivepe = npe; /* hard wired stopping logic */
618         level < (pc_gamg->Nlevels-1) && (level==0 || M>pc_gamg->coarse_eq_limit); /* && (npe==1 || nactivepe>1); */
619         level++ ){
620     level1 = level + 1;
621 #if defined PETSC_GAMG_USE_LOG
622     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET1],0,0,0,0); CHKERRQ(ierr);
623 #if (defined GAMG_STAGES)
624     ierr = PetscLogStagePush(gamg_stages[level]); CHKERRQ( ierr );
625 #endif
626 #endif
627     /* deal with Stokes, get sub matrices */
628     if( level > 0 ) {
629       ierr = GAMGKKTMatCreate( Aarr[level], stokes, &kktMatsArr[level] ); CHKERRQ(ierr);
630     }
631     { /* construct prolongator */
632       Mat Gmat;
633       PetscCoarsenData *agg_lists;
634       Mat Prol11,Prol22;
635 
636       level_bs[level] = bs;
637       ierr = pc_gamg->graph( pc,kktMatsArr[level].A11, &Gmat ); CHKERRQ(ierr);
638       ierr = pc_gamg->coarsen( pc, &Gmat, &agg_lists ); CHKERRQ(ierr);
639       ierr = pc_gamg->prolongator( pc, kktMatsArr[level].A11, Gmat, agg_lists, &Prol11 ); CHKERRQ(ierr);
640 
641       /* could have failed to create new level */
642       if( Prol11 ){
643         /* get new block size of coarse matrices */
644         ierr = MatGetBlockSizes( Prol11, PETSC_NULL, &bs ); CHKERRQ(ierr);
645 
646         if( stokes ) {
647           if(!pc_gamg->formkktprol) SETERRQ(wcomm,PETSC_ERR_USER,"Stokes not supportd by AMG method.");
648           /* R A12 == (T = A21 P)';  G = T' T; coarsen G; form plain agg with G */
649           ierr = pc_gamg->formkktprol( pc, Prol11, kktMatsArr[level].A21, &Prol22 ); CHKERRQ(ierr);
650         }
651 
652         if( pc_gamg->optprol ){
653           /* smooth */
654           ierr = pc_gamg->optprol( pc, kktMatsArr[level].A11, &Prol11 ); CHKERRQ(ierr);
655         }
656 
657         if( stokes ) {
658           IS is_row[2] = {kktMatsArr[level].prim_is,kktMatsArr[level].constr_is};
659           Mat a[4] = {Prol11, PETSC_NULL, PETSC_NULL, Prol22 };
660           ierr = MatCreateNest(wcomm,2,is_row, 2, is_row, a, &Parr[level1] ); CHKERRQ(ierr);
661         }
662         else {
663           Parr[level1] = Prol11;
664         }
665       }
666       else Parr[level1] = PETSC_NULL;
667 
668       if ( pc_gamg->use_aggs_in_gasm ) {
669         ierr = PetscCDGetASMBlocks(agg_lists, level_bs[level], &nASMBlocksArr[level], &ASMLocalIDsArr[level] );  CHKERRQ(ierr);
670       }
671 
672       ierr = PetscCDGetRemovedIS( agg_lists, &removedEqs[level] );  CHKERRQ(ierr);
673 
674       ierr = MatDestroy( &Gmat );      CHKERRQ(ierr);
675       ierr = PetscCDDestroy( agg_lists );  CHKERRQ(ierr);
676     } /* construct prolongator scope */
677 #if defined PETSC_GAMG_USE_LOG
678     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET1],0,0,0,0);CHKERRQ(ierr);
679 #endif
680     /* cache eigen estimate */
681     if( pc_gamg->emax_id != -1 ){
682       PetscBool flag;
683       ierr = PetscObjectComposedDataGetReal( (PetscObject)kktMatsArr[level].A11, pc_gamg->emax_id, emaxs[level], flag );
684       CHKERRQ( ierr );
685       if( !flag ) emaxs[level] = -1.;
686     }
687     else emaxs[level] = -1.;
688     if(level==0) Aarr[0] = Pmat; /* use Pmat for finest level setup */
689     if( !Parr[level1] ) {
690       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s stop gridding, level %d\n",mype,__FUNCT__,level);
691       break;
692     }
693 #if defined PETSC_GAMG_USE_LOG
694     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
695 #endif
696 
697     ierr = createLevel( pc, Aarr[level], bs, (PetscBool)(level==pc_gamg->Nlevels-2),
698                         stokes, &Parr[level1], &Aarr[level1], &nactivepe );
699     CHKERRQ(ierr);
700 
701 #if defined PETSC_GAMG_USE_LOG
702     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
703 #endif
704     ierr = MatGetSize( Aarr[level1], &M, &qq );CHKERRQ(ierr);
705 
706     if (pc_gamg->verbose > 0){
707       PetscInt NN = M;
708       if(pc_gamg->verbose==1) {
709         ierr = MatGetInfo(Aarr[level1],MAT_LOCAL,&info); CHKERRQ(ierr);
710         ierr = MatGetLocalSize( Aarr[level1], &NN, &qq );
711       }
712       else ierr = MatGetInfo( Aarr[level1], MAT_GLOBAL_SUM, &info );
713 
714       CHKERRQ(ierr);
715       nnztot += info.nz_used;
716       PetscPrintf(wcomm,"\t\t[%d]%s %d) N=%d, n data cols=%d, nnz/row (ave)=%d, %d active pes\n",
717                   mype,__FUNCT__,(int)level1,M,pc_gamg->data_cell_cols,
718                   (int)(info.nz_used/(PetscReal)NN), nactivepe );
719       CHKERRQ(ierr);
720     }
721 
722     /* stop if one node -- could pull back for singular problems */
723     if( M/pc_gamg->data_cell_cols < 2 ) {
724       level++;
725       break;
726     }
727 #if (defined PETSC_GAMG_USE_LOG && defined GAMG_STAGES)
728     ierr = PetscLogStagePop(); CHKERRQ( ierr );
729 #endif
730   } /* levels */
731 
732   if( pc_gamg->data ) {
733     ierr = PetscFree( pc_gamg->data ); CHKERRQ( ierr );
734     pc_gamg->data = PETSC_NULL;
735   }
736 
737   if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s %d levels, grid complexity = %g\n",0,__FUNCT__,level+1,nnztot/nnz0);
738   pc_gamg->Nlevels = level + 1;
739   fine_level = level;
740   ierr = PCMGSetLevels(pc,pc_gamg->Nlevels,PETSC_NULL);CHKERRQ(ierr);
741 
742   /* simple setup */
743   if( !PETSC_TRUE ){
744     PC_MG_Levels **mglevels = mg->levels;
745     for (lidx=0,level=pc_gamg->Nlevels-1;
746          lidx<fine_level;
747          lidx++, level--){
748       ierr = PCMGSetInterpolation( pc, lidx+1, Parr[level] );CHKERRQ(ierr);
749       ierr = KSPSetOperators( mglevels[lidx]->smoothd, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN );CHKERRQ(ierr);
750       ierr = MatDestroy( &Parr[level] );  CHKERRQ(ierr);
751       ierr = MatDestroy( &Aarr[level] );  CHKERRQ(ierr);
752     }
753     ierr = KSPSetOperators( mglevels[fine_level]->smoothd, Aarr[0], Aarr[0], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
754 
755     ierr = PCSetUp_MG( pc );  CHKERRQ( ierr );
756   }
757   else if( pc_gamg->Nlevels > 1 ) { /* don't setup MG if one level */
758     /* set default smoothers & set operators */
759     for ( lidx = 1, level = pc_gamg->Nlevels-2;
760           lidx <= fine_level;
761           lidx++, level--) {
762       KSP smoother;
763       PC subpc;
764 
765       ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
766       ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
767 
768       ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
769       /* set ops */
770       ierr = KSPSetOperators( smoother, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
771       ierr = PCMGSetInterpolation( pc, lidx, Parr[level+1] );CHKERRQ(ierr);
772 
773       /* create field split PC, get subsmoother */
774       if( stokes ) {
775         KSP *ksps;
776         PetscInt nn;
777         ierr = PCFieldSplitSetIS(subpc,"0",kktMatsArr[level].prim_is);   CHKERRQ(ierr);
778         ierr = PCFieldSplitSetIS(subpc,"1",kktMatsArr[level].constr_is); CHKERRQ(ierr);
779         ierr = PCFieldSplitGetSubKSP(subpc,&nn,&ksps); CHKERRQ(ierr);
780         smoother = ksps[0];
781         ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
782         ierr = PetscFree( ksps ); CHKERRQ(ierr);
783       }
784       ierr = GAMGKKTMatDestroy( &kktMatsArr[level] ); CHKERRQ(ierr);
785 
786       /* set defaults */
787       ierr = KSPSetType( smoother, KSPCHEBYCHEV );CHKERRQ(ierr);
788 
789       /* override defaults and command line args (!) */
790       if ( pc_gamg->use_aggs_in_gasm ) {
791         PetscInt sz;
792         IS *is;
793 
794         sz = nASMBlocksArr[level];
795         is = ASMLocalIDsArr[level];
796         ierr = PCSetType( subpc, PCGASM ); CHKERRQ(ierr);
797         if(sz==0){
798           IS is;
799           PetscInt my0,kk;
800           ierr = MatGetOwnershipRange( Aarr[level], &my0, &kk ); CHKERRQ(ierr);
801           ierr = ISCreateGeneral(PETSC_COMM_SELF, 1, &my0, PETSC_COPY_VALUES, &is ); CHKERRQ(ierr);
802           ierr = PCGASMSetLocalSubdomains( subpc, 1, &is, PETSC_NULL ); CHKERRQ(ierr);
803           ierr = ISDestroy( &is ); CHKERRQ(ierr);
804         }
805         else {
806           PetscInt kk;
807           ierr = PCGASMSetLocalSubdomains( subpc, sz, is, PETSC_NULL ); CHKERRQ(ierr);
808           for(kk=0;kk<sz;kk++){
809             ierr = ISDestroy( &is[kk] ); CHKERRQ(ierr);
810           }
811           ierr = PetscFree( is ); CHKERRQ(ierr);
812         }
813         ierr = PCGASMSetOverlap( subpc, 0 ); CHKERRQ(ierr);
814 
815         ASMLocalIDsArr[level] = PETSC_NULL;
816         nASMBlocksArr[level] = 0;
817         ierr = PCGASMSetType( subpc, PC_GASM_BASIC ); CHKERRQ(ierr);
818       }
819       else {
820         ierr = PCSetType( subpc, PCJACOBI ); CHKERRQ(ierr);
821       }
822     }
823     {
824       /* coarse grid */
825       KSP smoother,*k2; PC subpc,pc2; PetscInt ii,first;
826       Mat Lmat = Aarr[(level=pc_gamg->Nlevels-1)]; lidx = 0;
827       ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
828       ierr = KSPSetOperators( smoother, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ(ierr);
829       ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
830       ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
831       ierr = PCSetType( subpc, PCBJACOBI ); CHKERRQ(ierr);
832       ierr = PCSetUp( subpc ); CHKERRQ(ierr);
833       ierr = PCBJacobiGetSubKSP(subpc,&ii,&first,&k2);CHKERRQ(ierr);      assert(ii==1);
834       ierr = KSPGetPC(k2[0],&pc2);CHKERRQ(ierr);
835       ierr = PCSetType( pc2, PCLU ); CHKERRQ(ierr);
836     }
837 
838     /* should be called in PCSetFromOptions_GAMG(), but cannot be called prior to PCMGSetLevels() */
839     ierr = PetscObjectOptionsBegin( (PetscObject)pc );CHKERRQ(ierr);
840     ierr = PCSetFromOptions_MG( pc ); CHKERRQ(ierr);
841     ierr = PetscOptionsEnd();  CHKERRQ(ierr);
842     if (mg->galerkin != 2) SETERRQ(wcomm,PETSC_ERR_USER,"GAMG does Galerkin manually so the -pc_mg_galerkin option must not be used.");
843 
844     /* create cheby smoothers */
845     for ( lidx = 1, level = pc_gamg->Nlevels-2;
846           lidx <= fine_level;
847           lidx++, level--) {
848       KSP smoother;
849       PetscBool flag;
850       PC subpc;
851 
852       ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
853       ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
854 
855       /* create field split PC, get subsmoother */
856       if( stokes ) {
857         KSP *ksps;
858         PetscInt nn;
859         ierr = PCFieldSplitGetSubKSP(subpc,&nn,&ksps); CHKERRQ(ierr);
860         smoother = ksps[0];
861         ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
862         ierr = PetscFree( ksps );  CHKERRQ(ierr);
863       }
864 
865       /* do my own cheby */
866       ierr = PetscObjectTypeCompare( (PetscObject)smoother, KSPCHEBYCHEV, &flag ); CHKERRQ(ierr);
867       if( flag ) {
868         PetscReal emax, emin;
869         ierr = PetscObjectTypeCompare( (PetscObject)subpc, PCJACOBI, &flag ); CHKERRQ(ierr);
870         if( flag && emaxs[level] > 0.0 ) emax=emaxs[level]; /* eigen estimate only for diagnal PC */
871         else{ /* eigen estimate 'emax' */
872           KSP eksp; Mat Lmat = Aarr[level];
873           Vec bb, xx;
874 
875           ierr = MatGetVecs( Lmat, &bb, 0 );         CHKERRQ(ierr);
876           ierr = MatGetVecs( Lmat, &xx, 0 );         CHKERRQ(ierr);
877           {
878             PetscRandom    rctx;
879             ierr = PetscRandomCreate(wcomm,&rctx);CHKERRQ(ierr);
880             ierr = PetscRandomSetFromOptions(rctx);CHKERRQ(ierr);
881             ierr = VecSetRandom(bb,rctx);CHKERRQ(ierr);
882             ierr = PetscRandomDestroy( &rctx ); CHKERRQ(ierr);
883           }
884 
885           if( removedEqs[level] ) {
886             /* being very careful - zeroing out BC rows (this is not done in agg.c estimates) */
887             PetscScalar *zeros;
888             PetscInt ii,jj, *idx_bs, sz, bs=level_bs[level];
889             const PetscInt *idx;
890             ierr = ISGetLocalSize( removedEqs[level], &sz ); CHKERRQ(ierr);
891             ierr = PetscMalloc( bs*sz*sizeof(PetscScalar), &zeros ); CHKERRQ(ierr);
892             for(ii=0;ii<bs*sz;ii++) zeros[ii] = 0.;
893             ierr = PetscMalloc( bs*sz*sizeof(PetscInt), &idx_bs ); CHKERRQ(ierr);
894             ierr = ISGetIndices( removedEqs[level], &idx); CHKERRQ(ierr);
895             for(ii=0;ii<sz;ii++) {
896               for(jj=0;jj<bs;jj++) {
897                 idx_bs[ii] = bs*idx[ii]+jj;
898               }
899             }
900             ierr = ISRestoreIndices( removedEqs[level], &idx ); CHKERRQ(ierr);
901             if( sz > 0 ) {
902               ierr = VecSetValues( bb, sz, idx_bs, zeros, INSERT_VALUES );  CHKERRQ(ierr);
903             }
904             ierr = PetscFree( idx_bs );  CHKERRQ(ierr);
905             ierr = PetscFree( zeros );  CHKERRQ(ierr);
906             ierr = VecAssemblyBegin(bb); CHKERRQ(ierr);
907             ierr = VecAssemblyEnd(bb); CHKERRQ(ierr);
908           }
909           ierr = KSPCreate( wcomm, &eksp );CHKERRQ(ierr);
910           ierr = KSPSetTolerances( eksp, PETSC_DEFAULT, PETSC_DEFAULT, PETSC_DEFAULT, 10 );
911           CHKERRQ(ierr);
912           ierr = KSPSetNormType( eksp, KSP_NORM_NONE );                 CHKERRQ(ierr);
913           ierr = KSPSetOptionsPrefix(eksp,((PetscObject)pc)->prefix);CHKERRQ(ierr);
914           ierr = KSPAppendOptionsPrefix( eksp, "gamg_est_");         CHKERRQ(ierr);
915           ierr = KSPSetFromOptions( eksp );    CHKERRQ(ierr);
916 
917           ierr = KSPSetInitialGuessNonzero( eksp, PETSC_FALSE ); CHKERRQ(ierr);
918           ierr = KSPSetOperators( eksp, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ( ierr );
919           ierr = KSPSetComputeSingularValues( eksp,PETSC_TRUE ); CHKERRQ(ierr);
920 
921           /* set PC type to be same as smoother */
922           ierr = KSPSetPC( eksp, subpc ); CHKERRQ( ierr );
923 
924           /* solve - keep stuff out of logging */
925           ierr = PetscLogEventDeactivate(KSP_Solve);CHKERRQ(ierr);
926           ierr = PetscLogEventDeactivate(PC_Apply);CHKERRQ(ierr);
927           ierr = KSPSolve( eksp, bb, xx ); CHKERRQ(ierr);
928           ierr = PetscLogEventActivate(KSP_Solve);CHKERRQ(ierr);
929           ierr = PetscLogEventActivate(PC_Apply);CHKERRQ(ierr);
930 
931           ierr = KSPComputeExtremeSingularValues( eksp, &emax, &emin ); CHKERRQ(ierr);
932 
933           ierr = VecDestroy( &xx );       CHKERRQ(ierr);
934           ierr = VecDestroy( &bb );       CHKERRQ(ierr);
935           ierr = KSPDestroy( &eksp );       CHKERRQ(ierr);
936 
937           if( pc_gamg->verbose > 0 ) {
938             PetscInt N1, tt;
939             ierr = MatGetSize( Aarr[level], &N1, &tt );         CHKERRQ(ierr);
940             PetscPrintf(wcomm,"\t\t\t%s PC setup max eigen=%e min=%e on level %d (N=%d)\n",__FUNCT__,emax,emin,lidx,N1);
941           }
942         }
943         {
944           PetscInt N1, N0, tt;
945           ierr = MatGetSize( Aarr[level], &N1, &tt );         CHKERRQ(ierr);
946           ierr = MatGetSize( Aarr[level+1], &N0, &tt );       CHKERRQ(ierr);
947           /* heuristic - is this crap? */
948           emin = 1.*emax/((PetscReal)N1/(PetscReal)N0);
949           emax *= 1.05;
950         }
951         ierr = KSPChebychevSetEigenvalues( smoother, emax, emin );CHKERRQ(ierr);
952       } /* setup checby flag */
953 
954       if( removedEqs[level] ) {
955         ierr = ISDestroy( &removedEqs[level] );                    CHKERRQ(ierr);
956       }
957     } /* non-coarse levels */
958 
959     /* clean up */
960     for(level=1;level<pc_gamg->Nlevels;level++){
961       ierr = MatDestroy( &Parr[level] );  CHKERRQ(ierr);
962       ierr = MatDestroy( &Aarr[level] );  CHKERRQ(ierr);
963     }
964 
965     ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
966 
967     if( PETSC_FALSE ){
968       KSP smoother;  /* PCSetUp_MG seems to insists on setting this to GMRES on coarse grid */
969       ierr = PCMGGetSmoother( pc, 0, &smoother ); CHKERRQ(ierr);
970       ierr = KSPSetType( smoother, KSPPREONLY ); CHKERRQ(ierr);
971     }
972   }
973   else {
974     KSP smoother;
975     if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s one level solver used (system is seen as DD). Using default solver.\n",mype,__FUNCT__);
976     ierr = PCMGGetSmoother( pc, 0, &smoother ); CHKERRQ(ierr);
977     ierr = KSPSetOperators( smoother, Aarr[0], Aarr[0], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
978     ierr = KSPSetType( smoother, KSPPREONLY ); CHKERRQ(ierr);
979     ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
980   }
981 
982   PetscFunctionReturn(0);
983 }
984 
985 /* ------------------------------------------------------------------------- */
986 /*
987  PCDestroy_GAMG - Destroys the private context for the GAMG preconditioner
988    that was created with PCCreate_GAMG().
989 
990    Input Parameter:
991 .  pc - the preconditioner context
992 
993    Application Interface Routine: PCDestroy()
994 */
995 #undef __FUNCT__
996 #define __FUNCT__ "PCDestroy_GAMG"
997 PetscErrorCode PCDestroy_GAMG( PC pc )
998 {
999   PetscErrorCode  ierr;
1000   PC_MG           *mg = (PC_MG*)pc->data;
1001   PC_GAMG         *pc_gamg= (PC_GAMG*)mg->innerctx;
1002 
1003   PetscFunctionBegin;
1004   ierr = PCReset_GAMG( pc );CHKERRQ(ierr);
1005   ierr = PetscFree( pc_gamg );CHKERRQ(ierr);
1006   ierr = PCDestroy_MG( pc );CHKERRQ(ierr);
1007   PetscFunctionReturn(0);
1008 }
1009 
1010 
1011 #undef __FUNCT__
1012 #define __FUNCT__ "PCGAMGSetProcEqLim"
1013 /*@
1014    PCGAMGSetProcEqLim - Set number of equations to aim for on coarse grids via
1015    processor reduction.
1016 
1017    Not Collective on PC
1018 
1019    Input Parameters:
1020 .  pc - the preconditioner context
1021 
1022 
1023    Options Database Key:
1024 .  -pc_gamg_process_eq_limit
1025 
1026    Level: intermediate
1027 
1028    Concepts: Unstructured multrigrid preconditioner
1029 
1030 .seealso: ()
1031 @*/
1032 PetscErrorCode  PCGAMGSetProcEqLim(PC pc, PetscInt n)
1033 {
1034   PetscErrorCode ierr;
1035 
1036   PetscFunctionBegin;
1037   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1038   ierr = PetscTryMethod(pc,"PCGAMGSetProcEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1039   PetscFunctionReturn(0);
1040 }
1041 
1042 EXTERN_C_BEGIN
1043 #undef __FUNCT__
1044 #define __FUNCT__ "PCGAMGSetProcEqLim_GAMG"
1045 PetscErrorCode PCGAMGSetProcEqLim_GAMG(PC pc, PetscInt n)
1046 {
1047   PC_MG           *mg = (PC_MG*)pc->data;
1048   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1049 
1050   PetscFunctionBegin;
1051   if(n>0) pc_gamg->min_eq_proc = n;
1052   PetscFunctionReturn(0);
1053 }
1054 EXTERN_C_END
1055 
1056 #undef __FUNCT__
1057 #define __FUNCT__ "PCGAMGSetCoarseEqLim"
1058 /*@
1059    PCGAMGSetCoarseEqLim - Set max number of equations on coarse grids.
1060 
1061  Collective on PC
1062 
1063    Input Parameters:
1064 .  pc - the preconditioner context
1065 
1066 
1067    Options Database Key:
1068 .  -pc_gamg_coarse_eq_limit
1069 
1070    Level: intermediate
1071 
1072    Concepts: Unstructured multrigrid preconditioner
1073 
1074 .seealso: ()
1075  @*/
1076 PetscErrorCode PCGAMGSetCoarseEqLim(PC pc, PetscInt n)
1077 {
1078   PetscErrorCode ierr;
1079 
1080   PetscFunctionBegin;
1081   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1082   ierr = PetscTryMethod(pc,"PCGAMGSetCoarseEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1083   PetscFunctionReturn(0);
1084 }
1085 
1086 EXTERN_C_BEGIN
1087 #undef __FUNCT__
1088 #define __FUNCT__ "PCGAMGSetCoarseEqLim_GAMG"
1089 PetscErrorCode PCGAMGSetCoarseEqLim_GAMG(PC pc, PetscInt n)
1090 {
1091   PC_MG           *mg = (PC_MG*)pc->data;
1092   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1093 
1094   PetscFunctionBegin;
1095   if(n>0) pc_gamg->coarse_eq_limit = n;
1096   PetscFunctionReturn(0);
1097 }
1098 EXTERN_C_END
1099 
1100 #undef __FUNCT__
1101 #define __FUNCT__ "PCGAMGSetRepartitioning"
1102 /*@
1103    PCGAMGSetRepartitioning - Repartition the coarse grids
1104 
1105    Collective on PC
1106 
1107    Input Parameters:
1108 .  pc - the preconditioner context
1109 
1110 
1111    Options Database Key:
1112 .  -pc_gamg_repartition
1113 
1114    Level: intermediate
1115 
1116    Concepts: Unstructured multrigrid preconditioner
1117 
1118 .seealso: ()
1119 @*/
1120 PetscErrorCode PCGAMGSetRepartitioning(PC pc, PetscBool n)
1121 {
1122   PetscErrorCode ierr;
1123 
1124   PetscFunctionBegin;
1125   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1126   ierr = PetscTryMethod(pc,"PCGAMGSetRepartitioning_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
1127   PetscFunctionReturn(0);
1128 }
1129 
1130 EXTERN_C_BEGIN
1131 #undef __FUNCT__
1132 #define __FUNCT__ "PCGAMGSetRepartitioning_GAMG"
1133 PetscErrorCode PCGAMGSetRepartitioning_GAMG(PC pc, PetscBool n)
1134 {
1135   PC_MG           *mg = (PC_MG*)pc->data;
1136   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1137 
1138   PetscFunctionBegin;
1139   pc_gamg->repart = n;
1140   PetscFunctionReturn(0);
1141 }
1142 EXTERN_C_END
1143 
1144 #undef __FUNCT__
1145 #define __FUNCT__ "PCGAMGSetUseASMAggs"
1146 /*@
1147    PCGAMGSetUseASMAggs -
1148 
1149    Collective on PC
1150 
1151    Input Parameters:
1152 .  pc - the preconditioner context
1153 
1154 
1155    Options Database Key:
1156 .  -pc_gamg_use_agg_gasm
1157 
1158    Level: intermediate
1159 
1160    Concepts: Unstructured multrigrid preconditioner
1161 
1162 .seealso: ()
1163 @*/
1164 PetscErrorCode PCGAMGSetUseASMAggs(PC pc, PetscBool n)
1165 {
1166   PetscErrorCode ierr;
1167 
1168   PetscFunctionBegin;
1169   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1170   ierr = PetscTryMethod(pc,"PCGAMGSetUseASMAggs_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
1171   PetscFunctionReturn(0);
1172 }
1173 
1174 EXTERN_C_BEGIN
1175 #undef __FUNCT__
1176 #define __FUNCT__ "PCGAMGSetUseASMAggs_GAMG"
1177 PetscErrorCode PCGAMGSetUseASMAggs_GAMG(PC pc, PetscBool n)
1178 {
1179   PC_MG           *mg = (PC_MG*)pc->data;
1180   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1181 
1182   PetscFunctionBegin;
1183   pc_gamg->use_aggs_in_gasm = n;
1184   PetscFunctionReturn(0);
1185 }
1186 EXTERN_C_END
1187 
1188 #undef __FUNCT__
1189 #define __FUNCT__ "PCGAMGSetNlevels"
1190 /*@
1191    PCGAMGSetNlevels -
1192 
1193    Not collective on PC
1194 
1195    Input Parameters:
1196 .  pc - the preconditioner context
1197 
1198 
1199    Options Database Key:
1200 .  -pc_mg_levels
1201 
1202    Level: intermediate
1203 
1204    Concepts: Unstructured multrigrid preconditioner
1205 
1206 .seealso: ()
1207 @*/
1208 PetscErrorCode PCGAMGSetNlevels(PC pc, PetscInt n)
1209 {
1210   PetscErrorCode ierr;
1211 
1212   PetscFunctionBegin;
1213   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1214   ierr = PetscTryMethod(pc,"PCGAMGSetNlevels_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1215   PetscFunctionReturn(0);
1216 }
1217 
1218 EXTERN_C_BEGIN
1219 #undef __FUNCT__
1220 #define __FUNCT__ "PCGAMGSetNlevels_GAMG"
1221 PetscErrorCode PCGAMGSetNlevels_GAMG(PC pc, PetscInt n)
1222 {
1223   PC_MG           *mg = (PC_MG*)pc->data;
1224   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1225 
1226   PetscFunctionBegin;
1227   pc_gamg->Nlevels = n;
1228   PetscFunctionReturn(0);
1229 }
1230 EXTERN_C_END
1231 
1232 #undef __FUNCT__
1233 #define __FUNCT__ "PCGAMGSetThreshold"
1234 /*@
1235    PCGAMGSetThreshold - Relative threshold to use for dropping edges in aggregation graph
1236 
1237    Not collective on PC
1238 
1239    Input Parameters:
1240 .  pc - the preconditioner context
1241 
1242 
1243    Options Database Key:
1244 .  -pc_gamg_threshold
1245 
1246    Level: intermediate
1247 
1248    Concepts: Unstructured multrigrid preconditioner
1249 
1250 .seealso: ()
1251 @*/
1252 PetscErrorCode PCGAMGSetThreshold(PC pc, PetscReal n)
1253 {
1254   PetscErrorCode ierr;
1255 
1256   PetscFunctionBegin;
1257   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1258   ierr = PetscTryMethod(pc,"PCGAMGSetThreshold_C",(PC,PetscReal),(pc,n));CHKERRQ(ierr);
1259   PetscFunctionReturn(0);
1260 }
1261 
1262 EXTERN_C_BEGIN
1263 #undef __FUNCT__
1264 #define __FUNCT__ "PCGAMGSetThreshold_GAMG"
1265 PetscErrorCode PCGAMGSetThreshold_GAMG(PC pc, PetscReal n)
1266 {
1267   PC_MG           *mg = (PC_MG*)pc->data;
1268   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1269 
1270   PetscFunctionBegin;
1271   pc_gamg->threshold = n;
1272   PetscFunctionReturn(0);
1273 }
1274 EXTERN_C_END
1275 
1276 #undef __FUNCT__
1277 #define __FUNCT__ "PCGAMGSetType"
1278 /*@
1279    PCGAMGSetType - Set solution method - calls sub create method
1280 
1281    Collective on PC
1282 
1283    Input Parameters:
1284 .  pc - the preconditioner context
1285 
1286 
1287    Options Database Key:
1288 .  -pc_gamg_type
1289 
1290    Level: intermediate
1291 
1292    Concepts: Unstructured multrigrid preconditioner
1293 
1294 .seealso: ()
1295 @*/
1296 PetscErrorCode PCGAMGSetType( PC pc, const PCGAMGType type )
1297 {
1298   PetscErrorCode ierr;
1299 
1300   PetscFunctionBegin;
1301   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1302   ierr = PetscTryMethod(pc,"PCGAMGSetType_C",(PC,const PCGAMGType),(pc,type));
1303   CHKERRQ(ierr);
1304   PetscFunctionReturn(0);
1305 }
1306 
1307 EXTERN_C_BEGIN
1308 #undef __FUNCT__
1309 #define __FUNCT__ "PCGAMGSetType_GAMG"
1310 PetscErrorCode PCGAMGSetType_GAMG( PC pc, const PCGAMGType type )
1311 {
1312   PetscErrorCode ierr,(*r)(PC);
1313 
1314   PetscFunctionBegin;
1315   ierr = PetscFListFind(GAMGList,((PetscObject)pc)->comm,type,PETSC_FALSE,(PetscVoidStarFunction)&r);
1316   CHKERRQ(ierr);
1317 
1318   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unknown GAMG type %s given",type);
1319 
1320   /* call sub create method */
1321   ierr = (*r)(pc); CHKERRQ(ierr);
1322 
1323   PetscFunctionReturn(0);
1324 }
1325 EXTERN_C_END
1326 
1327 #undef __FUNCT__
1328 #define __FUNCT__ "PCSetFromOptions_GAMG"
1329 PetscErrorCode PCSetFromOptions_GAMG( PC pc )
1330 {
1331   PetscErrorCode  ierr;
1332   PC_MG           *mg = (PC_MG*)pc->data;
1333   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1334   PetscBool        flag;
1335   MPI_Comm         wcomm = ((PetscObject)pc)->comm;
1336 
1337   PetscFunctionBegin;
1338   ierr = PetscOptionsHead("GAMG options"); CHKERRQ(ierr);
1339   {
1340     /* -pc_gamg_verbose */
1341     ierr = PetscOptionsInt("-pc_gamg_verbose","Verbose (debugging) output for PCGAMG",
1342                            "none", pc_gamg->verbose,
1343                            &pc_gamg->verbose, PETSC_NULL );
1344     CHKERRQ(ierr);
1345 
1346     /* -pc_gamg_repartition */
1347     ierr = PetscOptionsBool("-pc_gamg_repartition",
1348                             "Repartion coarse grids (false)",
1349                             "PCGAMGRepartitioning",
1350                             pc_gamg->repart,
1351                             &pc_gamg->repart,
1352                             &flag);
1353     CHKERRQ(ierr);
1354 
1355     /* -pc_gamg_use_agg_gasm */
1356     ierr = PetscOptionsBool("-pc_gamg_use_agg_gasm",
1357                             "Use aggregation agragates for GASM smoother (false)",
1358                             "PCGAMGUseASMAggs",
1359                             pc_gamg->use_aggs_in_gasm,
1360                             &pc_gamg->use_aggs_in_gasm,
1361                             &flag);
1362     CHKERRQ(ierr);
1363 
1364     /* -pc_gamg_process_eq_limit */
1365     ierr = PetscOptionsInt("-pc_gamg_process_eq_limit",
1366                            "Limit (goal) on number of equations per process on coarse grids",
1367                            "PCGAMGSetProcEqLim",
1368                            pc_gamg->min_eq_proc,
1369                            &pc_gamg->min_eq_proc,
1370                            &flag );
1371     CHKERRQ(ierr);
1372 
1373     /* -pc_gamg_coarse_eq_limit */
1374     ierr = PetscOptionsInt("-pc_gamg_coarse_eq_limit",
1375                            "Limit on number of equations for the coarse grid",
1376                            "PCGAMGSetCoarseEqLim",
1377                            pc_gamg->coarse_eq_limit,
1378                            &pc_gamg->coarse_eq_limit,
1379                            &flag );
1380     CHKERRQ(ierr);
1381 
1382     /* -pc_gamg_threshold */
1383     ierr = PetscOptionsReal("-pc_gamg_threshold",
1384                             "Relative threshold to use for dropping edges in aggregation graph",
1385                             "PCGAMGSetThreshold",
1386                             pc_gamg->threshold,
1387                             &pc_gamg->threshold,
1388                             &flag );
1389     CHKERRQ(ierr);
1390     if(flag && pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s threshold set %e\n",0,__FUNCT__,pc_gamg->threshold);
1391 
1392     ierr = PetscOptionsInt("-pc_mg_levels",
1393                            "Set number of MG levels",
1394                            "PCGAMGSetNlevels",
1395                            pc_gamg->Nlevels,
1396                            &pc_gamg->Nlevels,
1397                            &flag );
1398   }
1399   ierr = PetscOptionsTail();CHKERRQ(ierr);
1400 
1401   PetscFunctionReturn(0);
1402 }
1403 
1404 /* -------------------------------------------------------------------------- */
1405 /*MC
1406      PCGAMG - Geometric algebraic multigrid (AMG) preconditioning framework.
1407        - This is the entry point to GAMG, registered in pcregis.c
1408 
1409    Options Database Keys:
1410    Multigrid options(inherited)
1411 +  -pc_mg_cycles <1>: 1 for V cycle, 2 for W-cycle (PCMGSetCycleType)
1412 .  -pc_mg_smoothup <1>: Number of post-smoothing steps (PCMGSetNumberSmoothUp)
1413 .  -pc_mg_smoothdown <1>: Number of pre-smoothing steps (PCMGSetNumberSmoothDown)
1414 -  -pc_mg_type <multiplicative>: (one of) additive multiplicative full cascade kascade
1415 
1416   Level: intermediate
1417 
1418   Concepts: multigrid
1419 
1420 .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC, PCMGType,
1421            PCMGSetLevels(), PCMGGetLevels(), PCMGSetType(), PCMGSetCycleType(), PCMGSetNumberSmoothDown(),
1422            PCMGSetNumberSmoothUp(), PCMGGetCoarseSolve(), PCMGSetResidual(), PCMGSetInterpolation(),
1423            PCMGSetRestriction(), PCMGGetSmoother(), PCMGGetSmootherUp(), PCMGGetSmootherDown(),
1424            PCMGSetCyclesOnLevel(), PCMGSetRhs(), PCMGSetX(), PCMGSetR()
1425 M*/
1426 EXTERN_C_BEGIN
1427 #undef __FUNCT__
1428 #define __FUNCT__ "PCCreate_GAMG"
1429 PetscErrorCode  PCCreate_GAMG( PC pc )
1430 {
1431   PetscErrorCode  ierr;
1432   PC_GAMG         *pc_gamg;
1433   PC_MG           *mg;
1434 #if defined PETSC_GAMG_USE_LOG
1435   static long count = 0;
1436 #endif
1437 
1438   PetscFunctionBegin;
1439 
1440   /* PCGAMG is an inherited class of PCMG. Initialize pc as PCMG */
1441   ierr = PCSetType( pc, PCMG );  CHKERRQ(ierr); /* calls PCCreate_MG() and MGCreate_Private() */
1442   ierr = PetscObjectChangeTypeName( (PetscObject)pc, PCGAMG ); CHKERRQ(ierr);
1443 
1444   /* create a supporting struct and attach it to pc */
1445   ierr = PetscNewLog( pc, PC_GAMG, &pc_gamg ); CHKERRQ(ierr);
1446   mg = (PC_MG*)pc->data;
1447   mg->galerkin = 2;             /* Use Galerkin, but it is computed externally */
1448   mg->innerctx = pc_gamg;
1449 
1450   pc_gamg->setup_count = 0;
1451   /* these should be in subctx but repartitioning needs simple arrays */
1452   pc_gamg->data_sz = 0;
1453   pc_gamg->data = 0;
1454 
1455   /* register AMG type */
1456   if( !GAMGList ){
1457     ierr = PetscFListAdd(&GAMGList,GAMGGEO,"PCCreateGAMG_GEO",(void(*)(void))PCCreateGAMG_GEO);CHKERRQ(ierr);
1458     ierr = PetscFListAdd(&GAMGList,GAMGAGG,"PCCreateGAMG_AGG",(void(*)(void))PCCreateGAMG_AGG);CHKERRQ(ierr);
1459   }
1460 
1461   /* overwrite the pointers of PCMG by the functions of base class PCGAMG */
1462   pc->ops->setfromoptions = PCSetFromOptions_GAMG;
1463   pc->ops->setup          = PCSetUp_GAMG;
1464   pc->ops->reset          = PCReset_GAMG;
1465   pc->ops->destroy        = PCDestroy_GAMG;
1466 
1467   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1468 					    "PCGAMGSetProcEqLim_C",
1469 					    "PCGAMGSetProcEqLim_GAMG",
1470 					    PCGAMGSetProcEqLim_GAMG);
1471   CHKERRQ(ierr);
1472 
1473   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1474 					    "PCGAMGSetCoarseEqLim_C",
1475 					    "PCGAMGSetCoarseEqLim_GAMG",
1476 					    PCGAMGSetCoarseEqLim_GAMG);
1477   CHKERRQ(ierr);
1478 
1479   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1480 					    "PCGAMGSetRepartitioning_C",
1481 					    "PCGAMGSetRepartitioning_GAMG",
1482 					    PCGAMGSetRepartitioning_GAMG);
1483   CHKERRQ(ierr);
1484 
1485   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1486 					    "PCGAMGSetUseASMAggs_C",
1487 					    "PCGAMGSetUseASMAggs_GAMG",
1488 					    PCGAMGSetUseASMAggs_GAMG);
1489   CHKERRQ(ierr);
1490 
1491   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1492 					    "PCGAMGSetThreshold_C",
1493 					    "PCGAMGSetThreshold_GAMG",
1494 					    PCGAMGSetThreshold_GAMG);
1495   CHKERRQ(ierr);
1496 
1497   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1498 					    "PCGAMGSetType_C",
1499 					    "PCGAMGSetType_GAMG",
1500 					    PCGAMGSetType_GAMG);
1501   CHKERRQ(ierr);
1502 
1503   pc_gamg->repart = PETSC_FALSE;
1504   pc_gamg->use_aggs_in_gasm = PETSC_FALSE;
1505   pc_gamg->min_eq_proc = 100;
1506   pc_gamg->coarse_eq_limit = 800;
1507   pc_gamg->threshold = 0.001;
1508   pc_gamg->Nlevels = GAMG_MAXLEVELS;
1509   pc_gamg->verbose = 0;
1510   pc_gamg->emax_id = -1;
1511 
1512   /* private events */
1513 #if defined PETSC_GAMG_USE_LOG
1514   if( count++ == 0 ) {
1515     PetscLogEventRegister("GAMG: createProl", PC_CLASSID, &petsc_gamg_setup_events[SET1]);
1516     PetscLogEventRegister("  Graph", PC_CLASSID, &petsc_gamg_setup_events[GRAPH]);
1517     /* PetscLogEventRegister("    G.Mat", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_MAT]); */
1518     /* PetscLogEventRegister("    G.Filter", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_FILTER]); */
1519     /* PetscLogEventRegister("    G.Square", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_SQR]); */
1520     PetscLogEventRegister("  MIS/Agg", PC_CLASSID, &petsc_gamg_setup_events[SET4]);
1521     PetscLogEventRegister("  geo: growSupp", PC_CLASSID, &petsc_gamg_setup_events[SET5]);
1522     PetscLogEventRegister("  geo: triangle", PC_CLASSID, &petsc_gamg_setup_events[SET6]);
1523     PetscLogEventRegister("    search&set", PC_CLASSID, &petsc_gamg_setup_events[FIND_V]);
1524     PetscLogEventRegister("  SA: col data", PC_CLASSID, &petsc_gamg_setup_events[SET7]);
1525     PetscLogEventRegister("  SA: frmProl0", PC_CLASSID, &petsc_gamg_setup_events[SET8]);
1526     PetscLogEventRegister("  SA: smooth", PC_CLASSID, &petsc_gamg_setup_events[SET9]);
1527     PetscLogEventRegister("GAMG: partLevel", PC_CLASSID, &petsc_gamg_setup_events[SET2]);
1528     PetscLogEventRegister("  repartition", PC_CLASSID, &petsc_gamg_setup_events[SET12]);
1529     PetscLogEventRegister("  Invert-Sort", PC_CLASSID, &petsc_gamg_setup_events[SET13]);
1530     PetscLogEventRegister("  Move A", PC_CLASSID, &petsc_gamg_setup_events[SET14]);
1531     PetscLogEventRegister("  Move P", PC_CLASSID, &petsc_gamg_setup_events[SET15]);
1532 
1533     /* PetscLogEventRegister(" PL move data", PC_CLASSID, &petsc_gamg_setup_events[SET13]); */
1534     /* PetscLogEventRegister("GAMG: fix", PC_CLASSID, &petsc_gamg_setup_events[SET10]); */
1535     /* PetscLogEventRegister("GAMG: set levels", PC_CLASSID, &petsc_gamg_setup_events[SET11]); */
1536     /* create timer stages */
1537 #if defined GAMG_STAGES
1538     {
1539       char str[32];
1540       sprintf(str,"MG Level %d (finest)",0);
1541       PetscLogStageRegister(str, &gamg_stages[0]);
1542       PetscInt lidx;
1543       for (lidx=1;lidx<9;lidx++){
1544 	sprintf(str,"MG Level %d",lidx);
1545 	PetscLogStageRegister(str, &gamg_stages[lidx]);
1546       }
1547     }
1548 #endif
1549   }
1550 #endif
1551   /* general events */
1552 #if defined PETSC_USE_LOG
1553   PetscLogEventRegister("PCGAMGgraph_AGG", 0, &PC_GAMGGgraph_AGG);
1554   PetscLogEventRegister("PCGAMGgraph_GEO", PC_CLASSID, &PC_GAMGGgraph_GEO);
1555   PetscLogEventRegister("PCGAMGcoarse_AGG", PC_CLASSID, &PC_GAMGCoarsen_AGG);
1556   PetscLogEventRegister("PCGAMGcoarse_GEO", PC_CLASSID, &PC_GAMGCoarsen_GEO);
1557   PetscLogEventRegister("PCGAMGProl_AGG", PC_CLASSID, &PC_GAMGProlongator_AGG);
1558   PetscLogEventRegister("PCGAMGProl_GEO", PC_CLASSID, &PC_GAMGProlongator_GEO);
1559   PetscLogEventRegister("PCGAMGPOpt_AGG", PC_CLASSID, &PC_GAMGOptprol_AGG);
1560   PetscLogEventRegister("GAMGKKTProl_AGG", PC_CLASSID, &PC_GAMGKKTProl_AGG);
1561 #endif
1562 
1563   /* instantiate derived type */
1564   ierr = PetscOptionsHead("GAMG options"); CHKERRQ(ierr);
1565   {
1566     char tname[256] = GAMGAGG;
1567     ierr = PetscOptionsList("-pc_gamg_type","Type of GAMG method","PCGAMGSetType",
1568                             GAMGList, tname, tname, sizeof(tname), PETSC_NULL );
1569     CHKERRQ(ierr);
1570     ierr = PCGAMGSetType( pc, tname ); CHKERRQ(ierr);
1571   }
1572   ierr = PetscOptionsTail();   CHKERRQ(ierr);
1573 
1574   PetscFunctionReturn(0);
1575 }
1576 EXTERN_C_END
1577