xref: /petsc/src/ksp/pc/impls/gamg/gamg.c (revision a2f3521de2a9d7869700f4c17e26c23fcfeaa6f6)
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   }
76   else {
77     out->A11 = A;
78     out->A21 = PETSC_NULL;
79     out->A12 = PETSC_NULL;
80     out->prim_is = PETSC_NULL;
81     out->constr_is = PETSC_NULL;
82   }
83   PetscFunctionReturn(0);
84 }
85 
86 #undef __FUNCT__
87 #define __FUNCT__ "GAMGKKTMatDestroy"
88 static PetscErrorCode GAMGKKTMatDestroy( GAMGKKTMat *mat )
89 {
90   PetscErrorCode   ierr;
91 
92   PetscFunctionBegin;
93   if( mat->A11 && mat->A11 != mat->Amat ) {
94     ierr = MatDestroy( &mat->A11 );  CHKERRQ(ierr);
95   }
96   ierr = MatDestroy( &mat->A21 );  CHKERRQ(ierr);
97   ierr = MatDestroy( &mat->A12 );  CHKERRQ(ierr);
98 
99   ierr = ISDestroy( &mat->prim_is );    CHKERRQ(ierr);
100   ierr = ISDestroy( &mat->constr_is );    CHKERRQ(ierr);
101 
102   PetscFunctionReturn(0);
103 }
104 
105 /* -------------------------------------------------------------------------- */
106 /*
107    createLevel: create coarse op with RAP.  repartition and/or reduce number
108      of active processors.
109 
110    Input Parameter:
111    . pc - parameters + side effect: coarse data in 'pc_gamg->data' and
112           'pc_gamg->data_sz' are changed via repartitioning/reduction.
113    . Amat_fine - matrix on this fine (k) level
114    . cbs - coarse block size
115    . isLast -
116    . stokes -
117    In/Output Parameter:
118    . a_P_inout - prolongation operator to the next level (k-->k-1)
119    . a_nactive_proc - number of active procs
120    Output Parameter:
121    . a_Amat_crs - coarse matrix that is created (k-1)
122 */
123 
124 #undef __FUNCT__
125 #define __FUNCT__ "createLevel"
126 static PetscErrorCode createLevel( const PC pc,
127                                    const Mat Amat_fine,
128                                    const PetscInt cbs,
129                                    const PetscBool isLast,
130                                    const PetscBool stokes,
131                                    Mat *a_P_inout,
132                                    Mat *a_Amat_crs,
133                                    PetscMPIInt *a_nactive_proc
134                                    )
135 {
136   PetscErrorCode   ierr;
137   PC_MG           *mg = (PC_MG*)pc->data;
138   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
139   const PetscBool  repart = pc_gamg->repart;
140   const PetscInt   min_eq_proc = pc_gamg->min_eq_proc, coarse_max = pc_gamg->coarse_eq_limit;
141   Mat              Cmat,Pold=*a_P_inout;
142   MPI_Comm         wcomm = ((PetscObject)Amat_fine)->comm;
143   PetscMPIInt      mype,npe,new_npe,nactive=*a_nactive_proc;
144   PetscInt         ncrs_eq,ncrs_prim;
145 
146   PetscFunctionBegin;
147   ierr = MPI_Comm_rank( wcomm, &mype ); CHKERRQ(ierr);
148   ierr = MPI_Comm_size( wcomm, &npe );  CHKERRQ(ierr);
149   /* RAP */
150   ierr = MatPtAP( Amat_fine, Pold, MAT_INITIAL_MATRIX, 2.0, &Cmat ); CHKERRQ(ierr);
151 
152   /* set 'ncrs_prim' (nodes), 'ncrs_eq' (equations)*/
153   ncrs_prim = pc_gamg->data_sz/pc_gamg->data_cell_cols/pc_gamg->data_cell_rows;
154   assert(pc_gamg->data_sz%(pc_gamg->data_cell_cols*pc_gamg->data_cell_rows)==0);
155   ierr = MatGetLocalSize( Cmat, &ncrs_eq, PETSC_NULL );  CHKERRQ(ierr);
156 
157   /* get number of PEs to make active 'new_npe', reduce, can be any integer 1-P */
158   {
159     PetscInt ncrs_eq_glob,ncrs_eq_ave;
160     ierr = MatGetSize( Cmat, &ncrs_eq_glob, PETSC_NULL );  CHKERRQ(ierr);
161     ncrs_eq_ave = ncrs_eq_glob/npe;
162     new_npe = (PetscMPIInt)((float)ncrs_eq_ave/(float)min_eq_proc + 0.5); /* hardwire min. number of eq/proc */
163     if( new_npe == 0 || ncrs_eq_ave < coarse_max ) new_npe = 1;
164     else if ( new_npe >= nactive ) new_npe = nactive; /* no change, rare */
165     if( isLast ) new_npe = 1;
166   }
167 
168   if( !repart && new_npe==nactive ) {
169     *a_Amat_crs = Cmat; /* output - no repartitioning or reduction - could bail here */
170     }
171   else {
172     const PetscInt *idx,ndata_rows=pc_gamg->data_cell_rows,ndata_cols=pc_gamg->data_cell_cols,node_data_sz=ndata_rows*ndata_cols;
173     PetscInt       *counts,*newproc_idx,ii,jj,kk,strideNew,*tidx,ncrs_prim_new,ncrs_eq_new,nloc_old;
174     IS              is_eq_newproc,is_eq_newproc_prim,is_eq_num,is_eq_num_prim,isscat,new_eq_indices;
175     VecScatter      vecscat;
176     PetscScalar    *array;
177     Vec             src_crd, dest_crd;
178 
179     nloc_old = ncrs_eq/cbs; assert(ncrs_eq%cbs==0);
180 #if defined PETSC_GAMG_USE_LOG
181     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET12],0,0,0,0);CHKERRQ(ierr);
182 #endif
183     /* make 'is_eq_newproc' */
184     ierr = PetscMalloc( npe*sizeof(PetscInt), &counts ); CHKERRQ(ierr);
185     if( repart && !stokes ) {
186       /* Repartition Cmat_{k} and move colums of P^{k}_{k-1} and coordinates of primal part accordingly */
187       Mat             adj;
188 
189       if (pc_gamg->verbose>0) {
190         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);
191         else {
192           PetscInt n;
193           ierr = MPI_Allreduce( &ncrs_eq, &n, 1, MPIU_INT, MPI_SUM, wcomm );CHKERRQ(ierr);
194           PetscPrintf(wcomm,"\t[%d]%s repartition: npe (active): %d --> %d, neq = %d\n",mype,__FUNCT__,*a_nactive_proc,new_npe,n);
195         }
196       }
197 
198       /* get 'adj' */
199       if( cbs == 1 ) {
200 	ierr = MatConvert( Cmat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
201       }
202       else{
203 	/* make a scalar matrix to partition (no Stokes here) */
204 	Mat tMat;
205 	PetscInt Istart_crs,Iend_crs,ncols,jj,Ii;
206 	const PetscScalar *vals;
207 	const PetscInt *idx;
208 	PetscInt *d_nnz, *o_nnz, M, N;
209 	static PetscInt llev = 0;
210 
211 	ierr = PetscMalloc( ncrs_prim*sizeof(PetscInt), &d_nnz ); CHKERRQ(ierr);
212 	ierr = PetscMalloc( ncrs_prim*sizeof(PetscInt), &o_nnz ); CHKERRQ(ierr);
213         ierr = MatGetOwnershipRange( Cmat, &Istart_crs, &Iend_crs );    CHKERRQ(ierr);
214         ierr = MatGetSize( Cmat, &M, &N );CHKERRQ(ierr);
215 	for ( Ii = Istart_crs, jj = 0 ; Ii < Iend_crs ; Ii += cbs, jj++ ) {
216 	  ierr = MatGetRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
217 	  d_nnz[jj] = ncols/cbs;
218 	  o_nnz[jj] = ncols/cbs;
219 	  ierr = MatRestoreRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
220 	  if( d_nnz[jj] > ncrs_prim ) d_nnz[jj] = ncrs_prim;
221 	  if( o_nnz[jj] > (M/cbs-ncrs_prim) ) o_nnz[jj] = M/cbs-ncrs_prim;
222 	}
223 
224 	ierr = MatCreate( wcomm, &tMat ); CHKERRQ(ierr);
225 	ierr = MatSetSizes( tMat, ncrs_prim, ncrs_prim,
226                             PETSC_DETERMINE, PETSC_DETERMINE );
227         CHKERRQ(ierr);
228         ierr = MatSetType(tMat,MATAIJ);   CHKERRQ(ierr);
229         ierr = MatSeqAIJSetPreallocation(tMat,0,d_nnz);CHKERRQ(ierr);
230         ierr = MatMPIAIJSetPreallocation(tMat,0,d_nnz,0,o_nnz);CHKERRQ(ierr);
231 	ierr = PetscFree( d_nnz ); CHKERRQ(ierr);
232 	ierr = PetscFree( o_nnz ); CHKERRQ(ierr);
233 
234 	for ( ii = Istart_crs; ii < Iend_crs; ii++ ) {
235 	  PetscInt dest_row = ii/cbs;
236 	  ierr = MatGetRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
237 	  for( jj = 0 ; jj < ncols ; jj++ ){
238 	    PetscInt dest_col = idx[jj]/cbs;
239 	    PetscScalar v = 1.0;
240 	    ierr = MatSetValues(tMat,1,&dest_row,1,&dest_col,&v,ADD_VALUES); CHKERRQ(ierr);
241 	  }
242 	  ierr = MatRestoreRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
243 	}
244 	ierr = MatAssemblyBegin(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
245 	ierr = MatAssemblyEnd(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
246 
247 	if( llev++ == -1 ) {
248 	  PetscViewer viewer; char fname[32];
249 	  ierr = PetscSNPrintf(fname,sizeof fname,"part_mat_%D.mat",llev);CHKERRQ(ierr);
250 	  PetscViewerBinaryOpen(wcomm,fname,FILE_MODE_WRITE,&viewer);
251 	  ierr = MatView( tMat, viewer ); CHKERRQ(ierr);
252 	  ierr = PetscViewerDestroy( &viewer );
253 	}
254 
255 	ierr = MatConvert( tMat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
256 
257 	ierr = MatDestroy( &tMat );  CHKERRQ(ierr);
258       } /* create 'adj' */
259 
260       { /* partition: get newproc_idx */
261 	char prefix[256];
262 	const char *pcpre;
263 	const PetscInt *is_idx;
264 	MatPartitioning  mpart;
265 	IS proc_is;
266 	PetscInt targetPE;
267 
268 	ierr = MatPartitioningCreate( wcomm, &mpart ); CHKERRQ(ierr);
269 	ierr = MatPartitioningSetAdjacency( mpart, adj ); CHKERRQ(ierr);
270 	ierr = PCGetOptionsPrefix( pc, &pcpre );CHKERRQ(ierr);
271 	ierr = PetscSNPrintf(prefix,sizeof prefix,"%spc_gamg_",pcpre?pcpre:"");CHKERRQ(ierr);
272 	ierr = PetscObjectSetOptionsPrefix((PetscObject)mpart,prefix);CHKERRQ(ierr);
273 	ierr = MatPartitioningSetFromOptions( mpart );    CHKERRQ(ierr);
274 	ierr = MatPartitioningSetNParts( mpart, new_npe );CHKERRQ(ierr);
275 	ierr = MatPartitioningApply( mpart, &proc_is ); CHKERRQ(ierr);
276 	ierr = MatPartitioningDestroy( &mpart );          CHKERRQ(ierr);
277 
278 	/* collect IS info */
279 	ierr = PetscMalloc( ncrs_eq*sizeof(PetscInt), &newproc_idx ); CHKERRQ(ierr);
280 	ierr = ISGetIndices( proc_is, &is_idx );        CHKERRQ(ierr);
281 	targetPE = 1; /* bring to "front" of machine */
282 	/*targetPE = npe/new_npe;*/ /* spread partitioning across machine */
283 	for( kk = jj = 0 ; kk < nloc_old ; kk++ ){
284 	  for( ii = 0 ; ii < cbs ; ii++, jj++ ){
285 	    newproc_idx[jj] = is_idx[kk] * targetPE; /* distribution */
286 	  }
287 	}
288 	ierr = ISRestoreIndices( proc_is, &is_idx );     CHKERRQ(ierr);
289 	ierr = ISDestroy( &proc_is );                    CHKERRQ(ierr);
290       }
291       ierr = MatDestroy( &adj );                       CHKERRQ(ierr);
292 
293       ierr = ISCreateGeneral( wcomm, ncrs_eq, newproc_idx, PETSC_COPY_VALUES, &is_eq_newproc );
294       CHKERRQ(ierr);
295       if( newproc_idx != 0 ) {
296 	ierr = PetscFree( newproc_idx );  CHKERRQ(ierr);
297       }
298     } /* repartitioning */
299     else { /* simple aggreagtion of parts -- 'is_eq_newproc' */
300 
301       PetscInt rfactor,targetPE;
302       /* find factor */
303       if( new_npe == 1 ) rfactor = npe; /* easy */
304       else {
305 	PetscReal best_fact = 0.;
306 	jj = -1;
307 	for( kk = 1 ; kk <= npe ; kk++ ){
308 	  if( npe%kk==0 ) { /* a candidate */
309 	    PetscReal nactpe = (PetscReal)npe/(PetscReal)kk, fact = nactpe/(PetscReal)new_npe;
310 	    if(fact > 1.0) fact = 1./fact; /* keep fact < 1 */
311 	    if( fact > best_fact ) {
312 	      best_fact = fact; jj = kk;
313 	    }
314 	  }
315 	}
316 	if( jj != -1 ) rfactor = jj;
317 	else rfactor = 1; /* does this happen .. a prime */
318       }
319       new_npe = npe/rfactor;
320 
321       if( new_npe==nactive ) {
322 	*a_Amat_crs = Cmat; /* output - no repartitioning or reduction, bail out because nested here */
323 	ierr = PetscFree( counts );  CHKERRQ(ierr);
324 	if (pc_gamg->verbose>0){
325           PetscPrintf(wcomm,"\t[%d]%s aggregate processors noop: new_npe=%d, neq(loc)=%d\n",mype,__FUNCT__,new_npe,ncrs_eq);
326         }
327 	PetscFunctionReturn(0);
328       }
329 
330       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s number of equations (loc) %d with simple aggregation\n",mype,__FUNCT__,ncrs_eq);
331       targetPE = mype/rfactor;
332       ierr = ISCreateStride( wcomm, ncrs_eq, targetPE, 0, &is_eq_newproc ); CHKERRQ(ierr);
333 
334       if( stokes ) {
335         ierr = ISCreateStride( wcomm, ncrs_prim*cbs, targetPE, 0, &is_eq_newproc_prim ); CHKERRQ(ierr);
336       }
337     } /* end simple 'is_eq_newproc' */
338 
339     /*
340      Create an index set from the is_eq_newproc index set to indicate the mapping TO
341      */
342     ierr = ISPartitioningToNumbering( is_eq_newproc, &is_eq_num ); CHKERRQ(ierr);
343     if( stokes ) {
344       ierr = ISPartitioningToNumbering( is_eq_newproc_prim, &is_eq_num_prim ); CHKERRQ(ierr);
345     }
346     else is_eq_num_prim = is_eq_num;
347     /*
348       Determine how many equations/vertices are assigned to each processor
349      */
350     ierr = ISPartitioningCount( is_eq_newproc, npe, counts ); CHKERRQ(ierr);
351     ncrs_eq_new = counts[mype];
352     ierr = ISDestroy( &is_eq_newproc );                       CHKERRQ(ierr);
353     if( stokes ) {
354       ierr = ISPartitioningCount( is_eq_newproc_prim, npe, counts ); CHKERRQ(ierr);
355       ierr = ISDestroy( &is_eq_newproc_prim );                       CHKERRQ(ierr);
356       ncrs_prim_new = counts[mype]/cbs; /* nodes */
357     }
358     else ncrs_prim_new = ncrs_eq_new/cbs; /* eqs */
359 
360     ierr = PetscFree( counts );  CHKERRQ(ierr);
361 #if defined PETSC_GAMG_USE_LOG
362     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET12],0,0,0,0);   CHKERRQ(ierr);
363 #endif
364 
365     /* move data (for primal equations only) */
366     /* Create a vector to contain the newly ordered element information */
367     ierr = VecCreate( wcomm, &dest_crd );
368     ierr = VecSetSizes( dest_crd, node_data_sz*ncrs_prim_new, PETSC_DECIDE ); CHKERRQ(ierr);
369     ierr = VecSetFromOptions( dest_crd ); CHKERRQ(ierr); /* this is needed! */
370     /*
371      There are 'ndata_rows*ndata_cols' data items per node, (one can think of the vectors of having
372      a block size of ...).  Note, ISs are expanded into equation space by 'cbs'.
373      */
374     ierr = PetscMalloc( (ncrs_prim*node_data_sz)*sizeof(PetscInt), &tidx ); CHKERRQ(ierr);
375     ierr = ISGetIndices( is_eq_num_prim, &idx ); CHKERRQ(ierr);
376     for(ii=0,jj=0; ii<ncrs_prim ; ii++) {
377       PetscInt id = idx[ii*cbs]/cbs; /* get node back */
378       for( kk=0; kk<node_data_sz ; kk++, jj++) tidx[jj] = id*node_data_sz + kk;
379     }
380     ierr = ISRestoreIndices( is_eq_num_prim, &idx ); CHKERRQ(ierr);
381     ierr = ISCreateGeneral( wcomm, node_data_sz*ncrs_prim, tidx, PETSC_COPY_VALUES, &isscat );
382     CHKERRQ(ierr);
383     ierr = PetscFree( tidx );  CHKERRQ(ierr);
384     /*
385      Create a vector to contain the original vertex information for each element
386      */
387     ierr = VecCreateSeq( PETSC_COMM_SELF, node_data_sz*ncrs_prim, &src_crd ); CHKERRQ(ierr);
388     for( jj=0; jj<ndata_cols ; jj++ ) {
389       const PetscInt stride0=ncrs_prim*pc_gamg->data_cell_rows;
390       for( ii=0 ; ii<ncrs_prim ; ii++) {
391 	for( kk=0; kk<ndata_rows ; kk++ ) {
392 	  PetscInt ix = ii*ndata_rows + kk + jj*stride0, jx = ii*node_data_sz + kk*ndata_cols + jj;
393           PetscScalar tt = (PetscScalar)pc_gamg->data[ix];
394 	  ierr = VecSetValues( src_crd, 1, &jx, &tt, INSERT_VALUES );  CHKERRQ(ierr);
395 	}
396       }
397     }
398     ierr = VecAssemblyBegin(src_crd); CHKERRQ(ierr);
399     ierr = VecAssemblyEnd(src_crd); CHKERRQ(ierr);
400     /*
401       Scatter the element vertex information (still in the original vertex ordering)
402       to the correct processor
403     */
404     ierr = VecScatterCreate( src_crd, PETSC_NULL, dest_crd, isscat, &vecscat);
405     CHKERRQ(ierr);
406     ierr = ISDestroy( &isscat );       CHKERRQ(ierr);
407     ierr = VecScatterBegin(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
408     ierr = VecScatterEnd(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
409     ierr = VecScatterDestroy( &vecscat );       CHKERRQ(ierr);
410     ierr = VecDestroy( &src_crd );       CHKERRQ(ierr);
411     /*
412       Put the element vertex data into a new allocation of the gdata->ele
413     */
414     ierr = PetscFree( pc_gamg->data );    CHKERRQ(ierr);
415     ierr = PetscMalloc( node_data_sz*ncrs_prim_new*sizeof(PetscReal), &pc_gamg->data );    CHKERRQ(ierr);
416     pc_gamg->data_sz = node_data_sz*ncrs_prim_new;
417     strideNew = ncrs_prim_new*ndata_rows;
418     ierr = VecGetArray( dest_crd, &array );    CHKERRQ(ierr);
419     for( jj=0; jj<ndata_cols ; jj++ ) {
420       for( ii=0 ; ii<ncrs_prim_new ; ii++) {
421 	for( kk=0; kk<ndata_rows ; kk++ ) {
422 	  PetscInt ix = ii*ndata_rows + kk + jj*strideNew, jx = ii*node_data_sz + kk*ndata_cols + jj;
423 	  pc_gamg->data[ix] = PetscRealPart(array[jx]);
424 	}
425       }
426     }
427     ierr = VecRestoreArray( dest_crd, &array );    CHKERRQ(ierr);
428     ierr = VecDestroy( &dest_crd );    CHKERRQ(ierr);
429 
430     /* move A and P (columns) with new layout */
431 #if defined PETSC_GAMG_USE_LOG
432     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
433 #endif
434 
435     /*
436       Invert for MatGetSubMatrix
437     */
438     ierr = ISInvertPermutation( is_eq_num, ncrs_eq_new, &new_eq_indices ); CHKERRQ(ierr);
439     ierr = ISSort( new_eq_indices ); CHKERRQ(ierr); /* is this needed? */
440     if(is_eq_num != is_eq_num_prim) {
441       ierr = ISDestroy( &is_eq_num_prim ); CHKERRQ(ierr); /* could be same as 'is_eq_num' */
442     }
443     ierr = ISDestroy( &is_eq_num ); CHKERRQ(ierr);
444 #if defined PETSC_GAMG_USE_LOG
445     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
446     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
447 #endif
448     /* 'a_Amat_crs' output */
449     {
450       Mat mat;
451       ierr = MatGetSubMatrix( Cmat, new_eq_indices, new_eq_indices, MAT_INITIAL_MATRIX, &mat );
452       CHKERRQ(ierr);
453       *a_Amat_crs = mat;
454     }
455     ierr = MatDestroy( &Cmat ); CHKERRQ(ierr);
456 
457 #if defined PETSC_GAMG_USE_LOG
458     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
459 #endif
460     /* prolongator */
461     {
462       IS findices;
463       PetscInt Istart,Iend;
464       Mat Pnew;
465       ierr = MatGetOwnershipRange( Pold, &Istart, &Iend );    CHKERRQ(ierr);
466 #if defined PETSC_GAMG_USE_LOG
467       ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
468 #endif
469       ierr = ISCreateStride(wcomm,Iend-Istart,Istart,1,&findices);   CHKERRQ(ierr);
470       ierr = MatGetSubMatrix( Pold, findices, new_eq_indices, MAT_INITIAL_MATRIX, &Pnew );
471       CHKERRQ(ierr);
472       ierr = ISDestroy( &findices ); CHKERRQ(ierr);
473 #if defined PETSC_GAMG_USE_LOG
474       ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
475 #endif
476       ierr = MatDestroy( a_P_inout ); CHKERRQ(ierr);
477 
478       /* output - repartitioned */
479       *a_P_inout = Pnew;
480     }
481     ierr = ISDestroy( &new_eq_indices ); CHKERRQ(ierr);
482 
483     *a_nactive_proc = new_npe; /* output */
484   }
485 
486   /* outout matrix data */
487   if( !PETSC_TRUE ) {
488     PetscViewer viewer; char fname[32]; static int llev=0; Cmat = *a_Amat_crs;
489     if(llev==0) {
490       sprintf(fname,"Cmat_%d.m",llev++);
491       PetscViewerASCIIOpen(wcomm,fname,&viewer);
492       ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
493       ierr = MatView(Amat_fine, viewer ); CHKERRQ(ierr);
494       ierr = PetscViewerDestroy( &viewer );
495     }
496     sprintf(fname,"Cmat_%d.m",llev++);
497     PetscViewerASCIIOpen(wcomm,fname,&viewer);
498     ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
499     ierr = MatView(Cmat, viewer ); CHKERRQ(ierr);
500     ierr = PetscViewerDestroy( &viewer );
501   }
502 
503   PetscFunctionReturn(0);
504 }
505 
506 /* -------------------------------------------------------------------------- */
507 /*
508    PCSetUp_GAMG - Prepares for the use of the GAMG preconditioner
509                     by setting data structures and options.
510 
511    Input Parameter:
512 .  pc - the preconditioner context
513 
514    Application Interface Routine: PCSetUp()
515 
516    Notes:
517    The interface routine PCSetUp() is not usually called directly by
518    the user, but instead is called by PCApply() if necessary.
519 */
520 #undef __FUNCT__
521 #define __FUNCT__ "PCSetUp_GAMG"
522 PetscErrorCode PCSetUp_GAMG( PC pc )
523 {
524   PetscErrorCode  ierr;
525   PC_MG           *mg = (PC_MG*)pc->data;
526   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
527   Mat              Pmat = pc->pmat;
528   PetscInt         fine_level,level,level1,bs,M,qq,lidx,nASMBlocksArr[GAMG_MAXLEVELS];
529   MPI_Comm         wcomm = ((PetscObject)pc)->comm;
530   PetscMPIInt      mype,npe,nactivepe;
531   Mat              Aarr[GAMG_MAXLEVELS],Parr[GAMG_MAXLEVELS];
532   PetscReal        emaxs[GAMG_MAXLEVELS];
533   IS              *ASMLocalIDsArr[GAMG_MAXLEVELS],removedEqs[GAMG_MAXLEVELS];
534   PetscInt         level_bs[GAMG_MAXLEVELS];
535   GAMGKKTMat       kktMatsArr[GAMG_MAXLEVELS];
536   PetscLogDouble   nnz0=0.,nnztot=0.;
537   MatInfo          info;
538   PetscBool        stokes = PETSC_FALSE;
539 
540   PetscFunctionBegin;
541   ierr = MPI_Comm_rank(wcomm,&mype);CHKERRQ(ierr);
542   ierr = MPI_Comm_size(wcomm,&npe);CHKERRQ(ierr);
543   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);
544   if( pc_gamg->setup_count++ > 0 ) {
545     PC_MG_Levels **mglevels = mg->levels;
546     /* just do Galerkin grids */
547     Mat B,dA,dB;
548     assert(pc->setupcalled);
549 
550     if( pc_gamg->Nlevels > 1 ) {
551       /* currently only handle case where mat and pmat are the same on coarser levels */
552       ierr = KSPGetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,&dA,&dB,PETSC_NULL);CHKERRQ(ierr);
553       /* (re)set to get dirty flag */
554       ierr = KSPSetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,dA,dB,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
555 
556       for (level=pc_gamg->Nlevels-2; level>-1; level--) {
557         /* the first time through the matrix structure has changed from repartitioning */
558         if( pc_gamg->setup_count==2 /*&& (pc_gamg->repart || level==0)*/) {
559           ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_INITIAL_MATRIX,1.0,&B);CHKERRQ(ierr);
560           ierr = MatDestroy(&mglevels[level]->A);CHKERRQ(ierr);
561           mglevels[level]->A = B;
562         }
563         else {
564           ierr = KSPGetOperators(mglevels[level]->smoothd,PETSC_NULL,&B,PETSC_NULL);CHKERRQ(ierr);
565           ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_REUSE_MATRIX,1.0,&B);CHKERRQ(ierr);
566         }
567         ierr = KSPSetOperators(mglevels[level]->smoothd,B,B,SAME_NONZERO_PATTERN); CHKERRQ(ierr);
568         dB = B;
569       }
570     }
571 
572     ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
573 
574     /* PCSetUp_MG seems to insists on setting this to GMRES */
575     ierr = KSPSetType( mglevels[0]->smoothd, KSPPREONLY ); CHKERRQ(ierr);
576 
577     PetscFunctionReturn(0);
578   }
579   assert(pc->setupcalled == 0);
580 
581   ierr = PetscOptionsGetBool(((PetscObject)pc)->prefix,"-pc_fieldsplit_detect_saddle_point",&stokes,PETSC_NULL);CHKERRQ(ierr);
582 
583   if( pc_gamg->data == 0 ) {
584     if( !pc_gamg->createdefaultdata ){
585       SETERRQ(wcomm,PETSC_ERR_LIB,"'createdefaultdata' not set(?) need to support NULL data");
586     }
587     if( stokes ) {
588       SETERRQ(wcomm,PETSC_ERR_LIB,"Need data (eg, PCSetCoordinates) for Stokes problems");
589     }
590     ierr = pc_gamg->createdefaultdata( pc, Pmat ); CHKERRQ(ierr);
591   }
592 
593   /* get basic dims */
594   if( stokes ) {
595     bs = pc_gamg->data_cell_rows; /* this is agg-mg specific */
596     /* nloc = pc_gamg->data_sz/pc_gamg->data_cell_cols/bs; assert(pc_gamg->data_sz%(pc_gamg->data_cell_cols*bs)==0); */
597   }
598   else {
599     /* PetscInt Istart,Iend,M,N; */
600     ierr = MatGetBlockSize( Pmat, &bs ); CHKERRQ(ierr);
601     /* ierr = MatGetSize( Pmat, &M, &N );CHKERRQ(ierr); */
602     /* ierr = MatGetOwnershipRange( Pmat, &Istart, &Iend ); CHKERRQ(ierr); */
603     /* nloc = (Iend-Istart)/bs; assert((Iend-Istart)%bs == 0); */
604   }
605 
606   ierr = MatGetSize( Pmat, &M, &qq );CHKERRQ(ierr);
607   if (pc_gamg->verbose) {
608     if(pc_gamg->verbose==1) ierr =  MatGetInfo(Pmat,MAT_LOCAL,&info);
609     else ierr = MatGetInfo(Pmat,MAT_GLOBAL_SUM,&info);
610     CHKERRQ(ierr);
611     nnz0 = info.nz_used;
612     nnztot = info.nz_used;
613     PetscPrintf(wcomm,"\t[%d]%s level %d N=%d, n data rows=%d, n data cols=%d, nnz/row (ave)=%d, np=%d\n",
614                 mype,__FUNCT__,0,M,pc_gamg->data_cell_rows,pc_gamg->data_cell_cols,
615                 (int)(nnz0/(PetscReal)M),npe);
616   }
617 
618   /* Get A_i and R_i */
619   for ( level=0, Aarr[0]=Pmat, nactivepe = npe; /* hard wired stopping logic */
620         level < (pc_gamg->Nlevels-1) && (level==0 || M>pc_gamg->coarse_eq_limit); /* && (npe==1 || nactivepe>1); */
621         level++ ){
622     level1 = level + 1;
623 #if defined PETSC_GAMG_USE_LOG
624     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET1],0,0,0,0); CHKERRQ(ierr);
625 #if (defined GAMG_STAGES)
626     ierr = PetscLogStagePush(gamg_stages[level]); CHKERRQ( ierr );
627 #endif
628 #endif
629     /* deal with Stokes, get sub matrices */
630     ierr = GAMGKKTMatCreate( Aarr[level], stokes, &kktMatsArr[level] ); CHKERRQ(ierr);
631 
632     { /* construct prolongator */
633       Mat Gmat;
634       PetscCoarsenData *agg_lists;
635       Mat Prol11,Prol22;
636 
637       level_bs[level] = bs;
638       ierr = pc_gamg->graph( pc,kktMatsArr[level].A11, &Gmat ); CHKERRQ(ierr);
639       ierr = pc_gamg->coarsen( pc, &Gmat, &agg_lists ); CHKERRQ(ierr);
640       ierr = pc_gamg->prolongator( pc, kktMatsArr[level].A11, Gmat, agg_lists, &Prol11 ); CHKERRQ(ierr);
641 
642       /* could have failed to create new level */
643       if( Prol11 ){
644         /* get new block size of coarse matrices */
645         if( pc_gamg->col_bs_id != -1 ){
646           PetscBool flag;
647           ierr = PetscObjectComposedDataGetInt( (PetscObject)Prol11, pc_gamg->col_bs_id, bs, flag );
648           CHKERRQ( ierr ); assert(flag);
649         }
650 
651         if( stokes ) {
652           if(!pc_gamg->formkktprol) SETERRQ(wcomm,PETSC_ERR_USER,"Stokes not supportd by AMG method.");
653           /* R A12 == (T = A21 P)';  G = T' T; coarsen G; form plain agg with G */
654           ierr = pc_gamg->formkktprol( pc, Prol11, kktMatsArr[level].A21, &Prol22 ); CHKERRQ(ierr);
655         }
656 
657         if( pc_gamg->optprol ){
658           /* smooth */
659           ierr = pc_gamg->optprol( pc, kktMatsArr[level].A11, &Prol11 ); CHKERRQ(ierr);
660         }
661 
662         if( stokes ) {
663           IS is_row[2] = {kktMatsArr[level].prim_is,kktMatsArr[level].constr_is};
664           Mat a[4] = {Prol11, PETSC_NULL, PETSC_NULL, Prol22 };
665           ierr = MatCreateNest(wcomm,2,is_row, 2, is_row, a, &Parr[level1] ); CHKERRQ(ierr);
666         }
667         else {
668           Parr[level1] = Prol11;
669         }
670       }
671       else Parr[level1] = PETSC_NULL;
672 
673       if ( pc_gamg->use_aggs_in_gasm ) {
674         ierr = PetscCDGetASMBlocks(agg_lists, level_bs[level], &nASMBlocksArr[level], &ASMLocalIDsArr[level] );  CHKERRQ(ierr);
675       }
676 
677       ierr = PetscCDGetRemovedIS( agg_lists, &removedEqs[level] );  CHKERRQ(ierr);
678 
679       ierr = MatDestroy( &Gmat );      CHKERRQ(ierr);
680       ierr = PetscCDDestroy( agg_lists );  CHKERRQ(ierr);
681     } /* construct prolongator scope */
682 #if defined PETSC_GAMG_USE_LOG
683     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET1],0,0,0,0);CHKERRQ(ierr);
684 #endif
685     /* cache eigen estimate */
686     if( pc_gamg->emax_id != -1 ){
687       PetscBool flag;
688       ierr = PetscObjectComposedDataGetReal( (PetscObject)kktMatsArr[level].A11, pc_gamg->emax_id, emaxs[level], flag );
689       CHKERRQ( ierr );
690       if( !flag ) emaxs[level] = -1.;
691     }
692     else emaxs[level] = -1.;
693     if(level==0) Aarr[0] = Pmat; /* use Pmat for finest level setup */
694     if( !Parr[level1] ) {
695       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s stop gridding, level %d\n",mype,__FUNCT__,level);
696       break;
697     }
698 #if defined PETSC_GAMG_USE_LOG
699     ierr = PetscLogEventBegin(petsc_gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
700 #endif
701 
702     ierr = createLevel( pc, Aarr[level], bs, (PetscBool)(level==pc_gamg->Nlevels-2),
703                         stokes, &Parr[level1], &Aarr[level1], &nactivepe );
704     CHKERRQ(ierr);
705 
706 #if defined PETSC_GAMG_USE_LOG
707     ierr = PetscLogEventEnd(petsc_gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
708 #endif
709     ierr = MatGetSize( Aarr[level1], &M, &qq );CHKERRQ(ierr);
710 
711     if (pc_gamg->verbose > 0){
712       PetscInt NN = M;
713       if(pc_gamg->verbose==1) {
714         ierr = MatGetInfo(Aarr[level1],MAT_LOCAL,&info); CHKERRQ(ierr);
715         ierr = MatGetLocalSize( Aarr[level1], &NN, &qq );
716       }
717       else ierr = MatGetInfo( Aarr[level1], MAT_GLOBAL_SUM, &info );
718 
719       CHKERRQ(ierr);
720       nnztot += info.nz_used;
721       PetscPrintf(wcomm,"\t\t[%d]%s %d) N=%d, n data cols=%d, nnz/row (ave)=%d, %d active pes\n",
722                   mype,__FUNCT__,(int)level1,M,pc_gamg->data_cell_cols,
723                   (int)(info.nz_used/(PetscReal)NN), nactivepe );
724       CHKERRQ(ierr);
725     }
726 
727     /* stop if one node -- could pull back for singular problems */
728     if( M/pc_gamg->data_cell_cols < 2 ) {
729       level++;
730       break;
731     }
732 #if (defined PETSC_GAMG_USE_LOG && defined GAMG_STAGES)
733     ierr = PetscLogStagePop(); CHKERRQ( ierr );
734 #endif
735   } /* levels */
736 
737   if( pc_gamg->data ) {
738     ierr = PetscFree( pc_gamg->data ); CHKERRQ( ierr );
739     pc_gamg->data = PETSC_NULL;
740   }
741 
742   if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s %d levels, grid complexity = %g\n",0,__FUNCT__,level+1,nnztot/nnz0);
743   pc_gamg->Nlevels = level + 1;
744   fine_level = level;
745   ierr = PCMGSetLevels(pc,pc_gamg->Nlevels,PETSC_NULL);CHKERRQ(ierr);
746 
747   /* simple setup */
748   if( !PETSC_TRUE ){
749     PC_MG_Levels **mglevels = mg->levels;
750     for (lidx=0,level=pc_gamg->Nlevels-1;
751          lidx<fine_level;
752          lidx++, level--){
753       ierr = PCMGSetInterpolation( pc, lidx+1, Parr[level] );CHKERRQ(ierr);
754       ierr = KSPSetOperators( mglevels[lidx]->smoothd, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN );CHKERRQ(ierr);
755       ierr = MatDestroy( &Parr[level] );  CHKERRQ(ierr);
756       ierr = MatDestroy( &Aarr[level] );  CHKERRQ(ierr);
757     }
758     ierr = KSPSetOperators( mglevels[fine_level]->smoothd, Aarr[0], Aarr[0], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
759 
760     ierr = PCSetUp_MG( pc );  CHKERRQ( ierr );
761   }
762   else if( pc_gamg->Nlevels > 1 ) { /* don't setup MG if one level */
763     /* set default smoothers & set operators */
764     for ( lidx = 1, level = pc_gamg->Nlevels-2;
765           lidx <= fine_level;
766           lidx++, level--) {
767       KSP smoother;
768       PC subpc;
769 
770       ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
771       ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
772 
773       ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
774       /* set ops */
775       ierr = KSPSetOperators( smoother, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
776       ierr = PCMGSetInterpolation( pc, lidx, Parr[level+1] );CHKERRQ(ierr);
777 
778       /* create field split PC, get subsmoother */
779       if( stokes ) {
780         KSP *ksps;
781         PetscInt nn;
782         ierr = PCFieldSplitSetIS(subpc,"0",kktMatsArr[level].prim_is);   CHKERRQ(ierr);
783         ierr = PCFieldSplitSetIS(subpc,"1",kktMatsArr[level].constr_is); CHKERRQ(ierr);
784         ierr = PCFieldSplitGetSubKSP(subpc,&nn,&ksps); CHKERRQ(ierr);
785         smoother = ksps[0];
786         ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
787         ierr = PetscFree( ksps ); CHKERRQ(ierr);
788       }
789       ierr = GAMGKKTMatDestroy( &kktMatsArr[level] ); CHKERRQ(ierr);
790 
791       /* set defaults */
792       ierr = KSPSetType( smoother, KSPCHEBYCHEV );CHKERRQ(ierr);
793 
794       /* override defaults and command line args (!) */
795       if ( pc_gamg->use_aggs_in_gasm ) {
796         PetscInt sz;
797         IS *is;
798 
799         sz = nASMBlocksArr[level];
800         is = ASMLocalIDsArr[level];
801         ierr = PCSetType( subpc, PCGASM ); CHKERRQ(ierr);
802         if(sz==0){
803           IS is;
804           PetscInt my0,kk;
805           ierr = MatGetOwnershipRange( Aarr[level], &my0, &kk ); CHKERRQ(ierr);
806           ierr = ISCreateGeneral(PETSC_COMM_SELF, 1, &my0, PETSC_COPY_VALUES, &is ); CHKERRQ(ierr);
807           ierr = PCGASMSetLocalSubdomains( subpc, 1, &is, PETSC_NULL ); CHKERRQ(ierr);
808           ierr = ISDestroy( &is ); CHKERRQ(ierr);
809         }
810         else {
811           PetscInt kk;
812           ierr = PCGASMSetLocalSubdomains( subpc, sz, is, PETSC_NULL ); CHKERRQ(ierr);
813           for(kk=0;kk<sz;kk++){
814             ierr = ISDestroy( &is[kk] ); CHKERRQ(ierr);
815           }
816           ierr = PetscFree( is ); CHKERRQ(ierr);
817         }
818         ierr = PCGASMSetOverlap( subpc, 0 ); CHKERRQ(ierr);
819 
820         ASMLocalIDsArr[level] = PETSC_NULL;
821         nASMBlocksArr[level] = 0;
822         ierr = PCGASMSetType( subpc, PC_GASM_BASIC ); CHKERRQ(ierr);
823       }
824       else {
825         ierr = PCSetType( subpc, PCJACOBI ); CHKERRQ(ierr);
826       }
827     }
828     {
829       /* coarse grid */
830       KSP smoother,*k2; PC subpc,pc2; PetscInt ii,first;
831       Mat Lmat = Aarr[(level=pc_gamg->Nlevels-1)]; lidx = 0;
832       ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
833       ierr = KSPSetOperators( smoother, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ(ierr);
834       ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
835       ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
836       ierr = PCSetType( subpc, PCBJACOBI ); CHKERRQ(ierr);
837       ierr = PCSetUp( subpc ); CHKERRQ(ierr);
838       ierr = PCBJacobiGetSubKSP(subpc,&ii,&first,&k2);CHKERRQ(ierr);      assert(ii==1);
839       ierr = KSPGetPC(k2[0],&pc2);CHKERRQ(ierr);
840       ierr = PCSetType( pc2, PCLU ); CHKERRQ(ierr);
841     }
842 
843     /* should be called in PCSetFromOptions_GAMG(), but cannot be called prior to PCMGSetLevels() */
844     ierr = PetscObjectOptionsBegin( (PetscObject)pc );CHKERRQ(ierr);
845     ierr = PCSetFromOptions_MG( pc ); CHKERRQ(ierr);
846     ierr = PetscOptionsEnd();  CHKERRQ(ierr);
847     if (mg->galerkin != 2) SETERRQ(wcomm,PETSC_ERR_USER,"GAMG does Galerkin manually so the -pc_mg_galerkin option must not be used.");
848 
849     /* create cheby smoothers */
850     for ( lidx = 1, level = pc_gamg->Nlevels-2;
851           lidx <= fine_level;
852           lidx++, level--) {
853       KSP smoother;
854       PetscBool flag;
855       PC subpc;
856 
857       ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
858       ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
859 
860       /* create field split PC, get subsmoother */
861       if( stokes ) {
862         KSP *ksps;
863         PetscInt nn;
864         ierr = PCFieldSplitGetSubKSP(subpc,&nn,&ksps); CHKERRQ(ierr);
865         smoother = ksps[0];
866         ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
867         ierr = PetscFree( ksps );  CHKERRQ(ierr);
868       }
869 
870       /* do my own cheby */
871       ierr = PetscObjectTypeCompare( (PetscObject)smoother, KSPCHEBYCHEV, &flag ); CHKERRQ(ierr);
872       if( flag ) {
873         PetscReal emax, emin;
874         ierr = PetscObjectTypeCompare( (PetscObject)subpc, PCJACOBI, &flag ); CHKERRQ(ierr);
875         if( flag && emaxs[level] > 0.0 ) emax=emaxs[level]; /* eigen estimate only for diagnal PC */
876         else{ /* eigen estimate 'emax' */
877           KSP eksp; Mat Lmat = Aarr[level];
878           Vec bb, xx;
879 
880           ierr = MatGetVecs( Lmat, &bb, 0 );         CHKERRQ(ierr);
881           ierr = MatGetVecs( Lmat, &xx, 0 );         CHKERRQ(ierr);
882           {
883             PetscRandom    rctx;
884             ierr = PetscRandomCreate(wcomm,&rctx);CHKERRQ(ierr);
885             ierr = PetscRandomSetFromOptions(rctx);CHKERRQ(ierr);
886             ierr = VecSetRandom(bb,rctx);CHKERRQ(ierr);
887             ierr = PetscRandomDestroy( &rctx ); CHKERRQ(ierr);
888           }
889 
890           if( removedEqs[level] ) {
891             /* being very careful - zeroing out BC rows (this is not done in agg.c estimates) */
892             PetscScalar *zeros;
893             PetscInt ii,jj, *idx_bs, sz, bs=level_bs[level];
894             const PetscInt *idx;
895             ierr = ISGetLocalSize( removedEqs[level], &sz ); CHKERRQ(ierr);
896             ierr = PetscMalloc( bs*sz*sizeof(PetscScalar), &zeros ); CHKERRQ(ierr);
897             for(ii=0;ii<bs*sz;ii++) zeros[ii] = 0.;
898             ierr = PetscMalloc( bs*sz*sizeof(PetscInt), &idx_bs ); CHKERRQ(ierr);
899             ierr = ISGetIndices( removedEqs[level], &idx); CHKERRQ(ierr);
900             for(ii=0;ii<sz;ii++) {
901               for(jj=0;jj<bs;jj++) {
902                 idx_bs[ii] = bs*idx[ii]+jj;
903               }
904             }
905             ierr = ISRestoreIndices( removedEqs[level], &idx ); CHKERRQ(ierr);
906             if( sz > 0 ) {
907               ierr = VecSetValues( bb, sz, idx_bs, zeros, INSERT_VALUES );  CHKERRQ(ierr);
908             }
909             ierr = PetscFree( idx_bs );  CHKERRQ(ierr);
910             ierr = PetscFree( zeros );  CHKERRQ(ierr);
911             ierr = VecAssemblyBegin(bb); CHKERRQ(ierr);
912             ierr = VecAssemblyEnd(bb); CHKERRQ(ierr);
913           }
914           ierr = KSPCreate( wcomm, &eksp );CHKERRQ(ierr);
915           ierr = KSPSetTolerances( eksp, PETSC_DEFAULT, PETSC_DEFAULT, PETSC_DEFAULT, 10 );
916           CHKERRQ(ierr);
917           ierr = KSPSetNormType( eksp, KSP_NORM_NONE );                 CHKERRQ(ierr);
918           ierr = KSPSetOptionsPrefix(eksp,((PetscObject)pc)->prefix);CHKERRQ(ierr);
919           ierr = KSPAppendOptionsPrefix( eksp, "gamg_est_");         CHKERRQ(ierr);
920           ierr = KSPSetFromOptions( eksp );    CHKERRQ(ierr);
921 
922           ierr = KSPSetInitialGuessNonzero( eksp, PETSC_FALSE ); CHKERRQ(ierr);
923           ierr = KSPSetOperators( eksp, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ( ierr );
924           ierr = KSPSetComputeSingularValues( eksp,PETSC_TRUE ); CHKERRQ(ierr);
925 
926           /* set PC type to be same as smoother */
927           ierr = KSPSetPC( eksp, subpc ); CHKERRQ( ierr );
928 
929           /* solve - keep stuff out of logging */
930           ierr = PetscLogEventDeactivate(KSP_Solve);CHKERRQ(ierr);
931           ierr = PetscLogEventDeactivate(PC_Apply);CHKERRQ(ierr);
932           ierr = KSPSolve( eksp, bb, xx ); CHKERRQ(ierr);
933           ierr = PetscLogEventActivate(KSP_Solve);CHKERRQ(ierr);
934           ierr = PetscLogEventActivate(PC_Apply);CHKERRQ(ierr);
935 
936           ierr = KSPComputeExtremeSingularValues( eksp, &emax, &emin ); CHKERRQ(ierr);
937 
938           ierr = VecDestroy( &xx );       CHKERRQ(ierr);
939           ierr = VecDestroy( &bb );       CHKERRQ(ierr);
940           ierr = KSPDestroy( &eksp );       CHKERRQ(ierr);
941 
942           if( pc_gamg->verbose > 0 ) {
943             PetscInt N1, tt;
944             ierr = MatGetSize( Aarr[level], &N1, &tt );         CHKERRQ(ierr);
945             PetscPrintf(wcomm,"\t\t\t%s PC setup max eigen=%e min=%e on level %d (N=%d)\n",__FUNCT__,emax,emin,lidx,N1);
946           }
947         }
948         {
949           PetscInt N1, N0, tt;
950           ierr = MatGetSize( Aarr[level], &N1, &tt );         CHKERRQ(ierr);
951           ierr = MatGetSize( Aarr[level+1], &N0, &tt );       CHKERRQ(ierr);
952           /* heuristic - is this crap? */
953           emin = 1.*emax/((PetscReal)N1/(PetscReal)N0);
954           emax *= 1.05;
955         }
956         ierr = KSPChebychevSetEigenvalues( smoother, emax, emin );CHKERRQ(ierr);
957       } /* setup checby flag */
958 
959       if( removedEqs[level] ) {
960         ierr = ISDestroy( &removedEqs[level] );                    CHKERRQ(ierr);
961       }
962     } /* non-coarse levels */
963 
964     /* clean up */
965     for(level=1;level<pc_gamg->Nlevels;level++){
966       ierr = MatDestroy( &Parr[level] );  CHKERRQ(ierr);
967       ierr = MatDestroy( &Aarr[level] );  CHKERRQ(ierr);
968     }
969 
970     ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
971 
972     if( PETSC_FALSE ){
973       KSP smoother;  /* PCSetUp_MG seems to insists on setting this to GMRES on coarse grid */
974       ierr = PCMGGetSmoother( pc, 0, &smoother ); CHKERRQ(ierr);
975       ierr = KSPSetType( smoother, KSPPREONLY ); CHKERRQ(ierr);
976     }
977   }
978   else {
979     KSP smoother;
980     if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s one level solver used (system is seen as DD). Using default solver.\n",mype,__FUNCT__);
981     ierr = PCMGGetSmoother( pc, 0, &smoother ); CHKERRQ(ierr);
982     ierr = KSPSetOperators( smoother, Aarr[0], Aarr[0], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
983     ierr = KSPSetType( smoother, KSPPREONLY ); CHKERRQ(ierr);
984     ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
985   }
986 
987   PetscFunctionReturn(0);
988 }
989 
990 /* ------------------------------------------------------------------------- */
991 /*
992  PCDestroy_GAMG - Destroys the private context for the GAMG preconditioner
993    that was created with PCCreate_GAMG().
994 
995    Input Parameter:
996 .  pc - the preconditioner context
997 
998    Application Interface Routine: PCDestroy()
999 */
1000 #undef __FUNCT__
1001 #define __FUNCT__ "PCDestroy_GAMG"
1002 PetscErrorCode PCDestroy_GAMG( PC pc )
1003 {
1004   PetscErrorCode  ierr;
1005   PC_MG           *mg = (PC_MG*)pc->data;
1006   PC_GAMG         *pc_gamg= (PC_GAMG*)mg->innerctx;
1007 
1008   PetscFunctionBegin;
1009   ierr = PCReset_GAMG( pc );CHKERRQ(ierr);
1010   ierr = PetscFree( pc_gamg );CHKERRQ(ierr);
1011   ierr = PCDestroy_MG( pc );CHKERRQ(ierr);
1012   PetscFunctionReturn(0);
1013 }
1014 
1015 
1016 #undef __FUNCT__
1017 #define __FUNCT__ "PCGAMGSetProcEqLim"
1018 /*@
1019    PCGAMGSetProcEqLim - Set number of equations to aim for on coarse grids via
1020    processor reduction.
1021 
1022    Not Collective on PC
1023 
1024    Input Parameters:
1025 .  pc - the preconditioner context
1026 
1027 
1028    Options Database Key:
1029 .  -pc_gamg_process_eq_limit
1030 
1031    Level: intermediate
1032 
1033    Concepts: Unstructured multrigrid preconditioner
1034 
1035 .seealso: ()
1036 @*/
1037 PetscErrorCode  PCGAMGSetProcEqLim(PC pc, PetscInt n)
1038 {
1039   PetscErrorCode ierr;
1040 
1041   PetscFunctionBegin;
1042   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1043   ierr = PetscTryMethod(pc,"PCGAMGSetProcEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1044   PetscFunctionReturn(0);
1045 }
1046 
1047 EXTERN_C_BEGIN
1048 #undef __FUNCT__
1049 #define __FUNCT__ "PCGAMGSetProcEqLim_GAMG"
1050 PetscErrorCode PCGAMGSetProcEqLim_GAMG(PC pc, PetscInt n)
1051 {
1052   PC_MG           *mg = (PC_MG*)pc->data;
1053   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1054 
1055   PetscFunctionBegin;
1056   if(n>0) pc_gamg->min_eq_proc = n;
1057   PetscFunctionReturn(0);
1058 }
1059 EXTERN_C_END
1060 
1061 #undef __FUNCT__
1062 #define __FUNCT__ "PCGAMGSetCoarseEqLim"
1063 /*@
1064    PCGAMGSetCoarseEqLim - Set max number of equations on coarse grids.
1065 
1066  Collective on PC
1067 
1068    Input Parameters:
1069 .  pc - the preconditioner context
1070 
1071 
1072    Options Database Key:
1073 .  -pc_gamg_coarse_eq_limit
1074 
1075    Level: intermediate
1076 
1077    Concepts: Unstructured multrigrid preconditioner
1078 
1079 .seealso: ()
1080  @*/
1081 PetscErrorCode PCGAMGSetCoarseEqLim(PC pc, PetscInt n)
1082 {
1083   PetscErrorCode ierr;
1084 
1085   PetscFunctionBegin;
1086   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1087   ierr = PetscTryMethod(pc,"PCGAMGSetCoarseEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1088   PetscFunctionReturn(0);
1089 }
1090 
1091 EXTERN_C_BEGIN
1092 #undef __FUNCT__
1093 #define __FUNCT__ "PCGAMGSetCoarseEqLim_GAMG"
1094 PetscErrorCode PCGAMGSetCoarseEqLim_GAMG(PC pc, PetscInt n)
1095 {
1096   PC_MG           *mg = (PC_MG*)pc->data;
1097   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1098 
1099   PetscFunctionBegin;
1100   if(n>0) pc_gamg->coarse_eq_limit = n;
1101   PetscFunctionReturn(0);
1102 }
1103 EXTERN_C_END
1104 
1105 #undef __FUNCT__
1106 #define __FUNCT__ "PCGAMGSetRepartitioning"
1107 /*@
1108    PCGAMGSetRepartitioning - Repartition the coarse grids
1109 
1110    Collective on PC
1111 
1112    Input Parameters:
1113 .  pc - the preconditioner context
1114 
1115 
1116    Options Database Key:
1117 .  -pc_gamg_repartition
1118 
1119    Level: intermediate
1120 
1121    Concepts: Unstructured multrigrid preconditioner
1122 
1123 .seealso: ()
1124 @*/
1125 PetscErrorCode PCGAMGSetRepartitioning(PC pc, PetscBool n)
1126 {
1127   PetscErrorCode ierr;
1128 
1129   PetscFunctionBegin;
1130   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1131   ierr = PetscTryMethod(pc,"PCGAMGSetRepartitioning_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
1132   PetscFunctionReturn(0);
1133 }
1134 
1135 EXTERN_C_BEGIN
1136 #undef __FUNCT__
1137 #define __FUNCT__ "PCGAMGSetRepartitioning_GAMG"
1138 PetscErrorCode PCGAMGSetRepartitioning_GAMG(PC pc, PetscBool n)
1139 {
1140   PC_MG           *mg = (PC_MG*)pc->data;
1141   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1142 
1143   PetscFunctionBegin;
1144   pc_gamg->repart = n;
1145   PetscFunctionReturn(0);
1146 }
1147 EXTERN_C_END
1148 
1149 #undef __FUNCT__
1150 #define __FUNCT__ "PCGAMGSetUseASMAggs"
1151 /*@
1152    PCGAMGSetUseASMAggs -
1153 
1154    Collective on PC
1155 
1156    Input Parameters:
1157 .  pc - the preconditioner context
1158 
1159 
1160    Options Database Key:
1161 .  -pc_gamg_use_agg_gasm
1162 
1163    Level: intermediate
1164 
1165    Concepts: Unstructured multrigrid preconditioner
1166 
1167 .seealso: ()
1168 @*/
1169 PetscErrorCode PCGAMGSetUseASMAggs(PC pc, PetscBool n)
1170 {
1171   PetscErrorCode ierr;
1172 
1173   PetscFunctionBegin;
1174   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1175   ierr = PetscTryMethod(pc,"PCGAMGSetUseASMAggs_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
1176   PetscFunctionReturn(0);
1177 }
1178 
1179 EXTERN_C_BEGIN
1180 #undef __FUNCT__
1181 #define __FUNCT__ "PCGAMGSetUseASMAggs_GAMG"
1182 PetscErrorCode PCGAMGSetUseASMAggs_GAMG(PC pc, PetscBool n)
1183 {
1184   PC_MG           *mg = (PC_MG*)pc->data;
1185   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1186 
1187   PetscFunctionBegin;
1188   pc_gamg->use_aggs_in_gasm = n;
1189   PetscFunctionReturn(0);
1190 }
1191 EXTERN_C_END
1192 
1193 #undef __FUNCT__
1194 #define __FUNCT__ "PCGAMGSetNlevels"
1195 /*@
1196    PCGAMGSetNlevels -
1197 
1198    Not collective on PC
1199 
1200    Input Parameters:
1201 .  pc - the preconditioner context
1202 
1203 
1204    Options Database Key:
1205 .  -pc_mg_levels
1206 
1207    Level: intermediate
1208 
1209    Concepts: Unstructured multrigrid preconditioner
1210 
1211 .seealso: ()
1212 @*/
1213 PetscErrorCode PCGAMGSetNlevels(PC pc, PetscInt n)
1214 {
1215   PetscErrorCode ierr;
1216 
1217   PetscFunctionBegin;
1218   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1219   ierr = PetscTryMethod(pc,"PCGAMGSetNlevels_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
1220   PetscFunctionReturn(0);
1221 }
1222 
1223 EXTERN_C_BEGIN
1224 #undef __FUNCT__
1225 #define __FUNCT__ "PCGAMGSetNlevels_GAMG"
1226 PetscErrorCode PCGAMGSetNlevels_GAMG(PC pc, PetscInt n)
1227 {
1228   PC_MG           *mg = (PC_MG*)pc->data;
1229   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1230 
1231   PetscFunctionBegin;
1232   pc_gamg->Nlevels = n;
1233   PetscFunctionReturn(0);
1234 }
1235 EXTERN_C_END
1236 
1237 #undef __FUNCT__
1238 #define __FUNCT__ "PCGAMGSetThreshold"
1239 /*@
1240    PCGAMGSetThreshold - Relative threshold to use for dropping edges in aggregation graph
1241 
1242    Not collective on PC
1243 
1244    Input Parameters:
1245 .  pc - the preconditioner context
1246 
1247 
1248    Options Database Key:
1249 .  -pc_gamg_threshold
1250 
1251    Level: intermediate
1252 
1253    Concepts: Unstructured multrigrid preconditioner
1254 
1255 .seealso: ()
1256 @*/
1257 PetscErrorCode PCGAMGSetThreshold(PC pc, PetscReal n)
1258 {
1259   PetscErrorCode ierr;
1260 
1261   PetscFunctionBegin;
1262   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1263   ierr = PetscTryMethod(pc,"PCGAMGSetThreshold_C",(PC,PetscReal),(pc,n));CHKERRQ(ierr);
1264   PetscFunctionReturn(0);
1265 }
1266 
1267 EXTERN_C_BEGIN
1268 #undef __FUNCT__
1269 #define __FUNCT__ "PCGAMGSetThreshold_GAMG"
1270 PetscErrorCode PCGAMGSetThreshold_GAMG(PC pc, PetscReal n)
1271 {
1272   PC_MG           *mg = (PC_MG*)pc->data;
1273   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1274 
1275   PetscFunctionBegin;
1276   pc_gamg->threshold = n;
1277   PetscFunctionReturn(0);
1278 }
1279 EXTERN_C_END
1280 
1281 #undef __FUNCT__
1282 #define __FUNCT__ "PCGAMGSetType"
1283 /*@
1284    PCGAMGSetType - Set solution method - calls sub create method
1285 
1286    Collective on PC
1287 
1288    Input Parameters:
1289 .  pc - the preconditioner context
1290 
1291 
1292    Options Database Key:
1293 .  -pc_gamg_type
1294 
1295    Level: intermediate
1296 
1297    Concepts: Unstructured multrigrid preconditioner
1298 
1299 .seealso: ()
1300 @*/
1301 PetscErrorCode PCGAMGSetType( PC pc, const PCGAMGType type )
1302 {
1303   PetscErrorCode ierr;
1304 
1305   PetscFunctionBegin;
1306   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1307   ierr = PetscTryMethod(pc,"PCGAMGSetType_C",(PC,const PCGAMGType),(pc,type));
1308   CHKERRQ(ierr);
1309   PetscFunctionReturn(0);
1310 }
1311 
1312 EXTERN_C_BEGIN
1313 #undef __FUNCT__
1314 #define __FUNCT__ "PCGAMGSetType_GAMG"
1315 PetscErrorCode PCGAMGSetType_GAMG( PC pc, const PCGAMGType type )
1316 {
1317   PetscErrorCode ierr,(*r)(PC);
1318 
1319   PetscFunctionBegin;
1320   ierr = PetscFListFind(GAMGList,((PetscObject)pc)->comm,type,PETSC_FALSE,(PetscVoidStarFunction)&r);
1321   CHKERRQ(ierr);
1322 
1323   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unknown GAMG type %s given",type);
1324 
1325   /* call sub create method */
1326   ierr = (*r)(pc); CHKERRQ(ierr);
1327 
1328   PetscFunctionReturn(0);
1329 }
1330 EXTERN_C_END
1331 
1332 #undef __FUNCT__
1333 #define __FUNCT__ "PCSetFromOptions_GAMG"
1334 PetscErrorCode PCSetFromOptions_GAMG( PC pc )
1335 {
1336   PetscErrorCode  ierr;
1337   PC_MG           *mg = (PC_MG*)pc->data;
1338   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1339   PetscBool        flag;
1340   MPI_Comm         wcomm = ((PetscObject)pc)->comm;
1341 
1342   PetscFunctionBegin;
1343   ierr = PetscOptionsHead("GAMG options"); CHKERRQ(ierr);
1344   {
1345     /* -pc_gamg_verbose */
1346     ierr = PetscOptionsInt("-pc_gamg_verbose","Verbose (debugging) output for PCGAMG",
1347                            "none", pc_gamg->verbose,
1348                            &pc_gamg->verbose, PETSC_NULL );
1349     CHKERRQ(ierr);
1350 
1351     /* -pc_gamg_repartition */
1352     ierr = PetscOptionsBool("-pc_gamg_repartition",
1353                             "Repartion coarse grids (false)",
1354                             "PCGAMGRepartitioning",
1355                             pc_gamg->repart,
1356                             &pc_gamg->repart,
1357                             &flag);
1358     CHKERRQ(ierr);
1359 
1360     /* -pc_gamg_use_agg_gasm */
1361     ierr = PetscOptionsBool("-pc_gamg_use_agg_gasm",
1362                             "Use aggregation agragates for GASM smoother (false)",
1363                             "PCGAMGUseASMAggs",
1364                             pc_gamg->use_aggs_in_gasm,
1365                             &pc_gamg->use_aggs_in_gasm,
1366                             &flag);
1367     CHKERRQ(ierr);
1368 
1369     /* -pc_gamg_process_eq_limit */
1370     ierr = PetscOptionsInt("-pc_gamg_process_eq_limit",
1371                            "Limit (goal) on number of equations per process on coarse grids",
1372                            "PCGAMGSetProcEqLim",
1373                            pc_gamg->min_eq_proc,
1374                            &pc_gamg->min_eq_proc,
1375                            &flag );
1376     CHKERRQ(ierr);
1377 
1378     /* -pc_gamg_coarse_eq_limit */
1379     ierr = PetscOptionsInt("-pc_gamg_coarse_eq_limit",
1380                            "Limit on number of equations for the coarse grid",
1381                            "PCGAMGSetCoarseEqLim",
1382                            pc_gamg->coarse_eq_limit,
1383                            &pc_gamg->coarse_eq_limit,
1384                            &flag );
1385     CHKERRQ(ierr);
1386 
1387     /* -pc_gamg_threshold */
1388     ierr = PetscOptionsReal("-pc_gamg_threshold",
1389                             "Relative threshold to use for dropping edges in aggregation graph",
1390                             "PCGAMGSetThreshold",
1391                             pc_gamg->threshold,
1392                             &pc_gamg->threshold,
1393                             &flag );
1394     CHKERRQ(ierr);
1395     if(flag && pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s threshold set %e\n",0,__FUNCT__,pc_gamg->threshold);
1396 
1397     ierr = PetscOptionsInt("-pc_mg_levels",
1398                            "Set number of MG levels",
1399                            "PCGAMGSetNlevels",
1400                            pc_gamg->Nlevels,
1401                            &pc_gamg->Nlevels,
1402                            &flag );
1403   }
1404   ierr = PetscOptionsTail();CHKERRQ(ierr);
1405 
1406   PetscFunctionReturn(0);
1407 }
1408 
1409 /* -------------------------------------------------------------------------- */
1410 /*MC
1411      PCGAMG - Geometric algebraic multigrid (AMG) preconditioning framework.
1412        - This is the entry point to GAMG, registered in pcregis.c
1413 
1414    Options Database Keys:
1415    Multigrid options(inherited)
1416 +  -pc_mg_cycles <1>: 1 for V cycle, 2 for W-cycle (PCMGSetCycleType)
1417 .  -pc_mg_smoothup <1>: Number of post-smoothing steps (PCMGSetNumberSmoothUp)
1418 .  -pc_mg_smoothdown <1>: Number of pre-smoothing steps (PCMGSetNumberSmoothDown)
1419 -  -pc_mg_type <multiplicative>: (one of) additive multiplicative full cascade kascade
1420 
1421   Level: intermediate
1422 
1423   Concepts: multigrid
1424 
1425 .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC, PCMGType,
1426            PCMGSetLevels(), PCMGGetLevels(), PCMGSetType(), PCMGSetCycleType(), PCMGSetNumberSmoothDown(),
1427            PCMGSetNumberSmoothUp(), PCMGGetCoarseSolve(), PCMGSetResidual(), PCMGSetInterpolation(),
1428            PCMGSetRestriction(), PCMGGetSmoother(), PCMGGetSmootherUp(), PCMGGetSmootherDown(),
1429            PCMGSetCyclesOnLevel(), PCMGSetRhs(), PCMGSetX(), PCMGSetR()
1430 M*/
1431 EXTERN_C_BEGIN
1432 #undef __FUNCT__
1433 #define __FUNCT__ "PCCreate_GAMG"
1434 PetscErrorCode  PCCreate_GAMG( PC pc )
1435 {
1436   PetscErrorCode  ierr;
1437   PC_GAMG         *pc_gamg;
1438   PC_MG           *mg;
1439 #if defined PETSC_GAMG_USE_LOG
1440   static long count = 0;
1441 #endif
1442 
1443   PetscFunctionBegin;
1444 
1445   /* PCGAMG is an inherited class of PCMG. Initialize pc as PCMG */
1446   ierr = PCSetType( pc, PCMG );  CHKERRQ(ierr); /* calls PCCreate_MG() and MGCreate_Private() */
1447   ierr = PetscObjectChangeTypeName( (PetscObject)pc, PCGAMG ); CHKERRQ(ierr);
1448 
1449   /* create a supporting struct and attach it to pc */
1450   ierr = PetscNewLog( pc, PC_GAMG, &pc_gamg ); CHKERRQ(ierr);
1451   mg = (PC_MG*)pc->data;
1452   mg->galerkin = 2;             /* Use Galerkin, but it is computed externally */
1453   mg->innerctx = pc_gamg;
1454 
1455   pc_gamg->setup_count = 0;
1456   /* these should be in subctx but repartitioning needs simple arrays */
1457   pc_gamg->data_sz = 0;
1458   pc_gamg->data = 0;
1459 
1460   /* register AMG type */
1461   if( !GAMGList ){
1462     ierr = PetscFListAdd(&GAMGList,GAMGGEO,"PCCreateGAMG_GEO",(void(*)(void))PCCreateGAMG_GEO);CHKERRQ(ierr);
1463     ierr = PetscFListAdd(&GAMGList,GAMGAGG,"PCCreateGAMG_AGG",(void(*)(void))PCCreateGAMG_AGG);CHKERRQ(ierr);
1464   }
1465 
1466   /* overwrite the pointers of PCMG by the functions of base class PCGAMG */
1467   pc->ops->setfromoptions = PCSetFromOptions_GAMG;
1468   pc->ops->setup          = PCSetUp_GAMG;
1469   pc->ops->reset          = PCReset_GAMG;
1470   pc->ops->destroy        = PCDestroy_GAMG;
1471 
1472   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1473 					    "PCGAMGSetProcEqLim_C",
1474 					    "PCGAMGSetProcEqLim_GAMG",
1475 					    PCGAMGSetProcEqLim_GAMG);
1476   CHKERRQ(ierr);
1477 
1478   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1479 					    "PCGAMGSetCoarseEqLim_C",
1480 					    "PCGAMGSetCoarseEqLim_GAMG",
1481 					    PCGAMGSetCoarseEqLim_GAMG);
1482   CHKERRQ(ierr);
1483 
1484   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1485 					    "PCGAMGSetRepartitioning_C",
1486 					    "PCGAMGSetRepartitioning_GAMG",
1487 					    PCGAMGSetRepartitioning_GAMG);
1488   CHKERRQ(ierr);
1489 
1490   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1491 					    "PCGAMGSetUseASMAggs_C",
1492 					    "PCGAMGSetUseASMAggs_GAMG",
1493 					    PCGAMGSetUseASMAggs_GAMG);
1494   CHKERRQ(ierr);
1495 
1496   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1497 					    "PCGAMGSetThreshold_C",
1498 					    "PCGAMGSetThreshold_GAMG",
1499 					    PCGAMGSetThreshold_GAMG);
1500   CHKERRQ(ierr);
1501 
1502   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1503 					    "PCGAMGSetType_C",
1504 					    "PCGAMGSetType_GAMG",
1505 					    PCGAMGSetType_GAMG);
1506   CHKERRQ(ierr);
1507 
1508   pc_gamg->repart = PETSC_FALSE;
1509   pc_gamg->use_aggs_in_gasm = PETSC_FALSE;
1510   pc_gamg->min_eq_proc = 100;
1511   pc_gamg->coarse_eq_limit = 800;
1512   pc_gamg->threshold = 0.001;
1513   pc_gamg->Nlevels = GAMG_MAXLEVELS;
1514   pc_gamg->verbose = 0;
1515   pc_gamg->emax_id = -1;
1516   pc_gamg->col_bs_id = -1;
1517 
1518   /* private events */
1519 #if defined PETSC_GAMG_USE_LOG
1520   if( count++ == 0 ) {
1521     PetscLogEventRegister("GAMG: createProl", PC_CLASSID, &petsc_gamg_setup_events[SET1]);
1522     PetscLogEventRegister("  Graph", PC_CLASSID, &petsc_gamg_setup_events[GRAPH]);
1523     /* PetscLogEventRegister("    G.Mat", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_MAT]); */
1524     /* PetscLogEventRegister("    G.Filter", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_FILTER]); */
1525     /* PetscLogEventRegister("    G.Square", PC_CLASSID, &petsc_gamg_setup_events[GRAPH_SQR]); */
1526     PetscLogEventRegister("  MIS/Agg", PC_CLASSID, &petsc_gamg_setup_events[SET4]);
1527     PetscLogEventRegister("  geo: growSupp", PC_CLASSID, &petsc_gamg_setup_events[SET5]);
1528     PetscLogEventRegister("  geo: triangle", PC_CLASSID, &petsc_gamg_setup_events[SET6]);
1529     PetscLogEventRegister("    search&set", PC_CLASSID, &petsc_gamg_setup_events[FIND_V]);
1530     PetscLogEventRegister("  SA: col data", PC_CLASSID, &petsc_gamg_setup_events[SET7]);
1531     PetscLogEventRegister("  SA: frmProl0", PC_CLASSID, &petsc_gamg_setup_events[SET8]);
1532     PetscLogEventRegister("  SA: smooth", PC_CLASSID, &petsc_gamg_setup_events[SET9]);
1533     PetscLogEventRegister("GAMG: partLevel", PC_CLASSID, &petsc_gamg_setup_events[SET2]);
1534     PetscLogEventRegister("  repartition", PC_CLASSID, &petsc_gamg_setup_events[SET12]);
1535     PetscLogEventRegister("  Invert-Sort", PC_CLASSID, &petsc_gamg_setup_events[SET13]);
1536     PetscLogEventRegister("  Move A", PC_CLASSID, &petsc_gamg_setup_events[SET14]);
1537     PetscLogEventRegister("  Move P", PC_CLASSID, &petsc_gamg_setup_events[SET15]);
1538 
1539     /* PetscLogEventRegister(" PL move data", PC_CLASSID, &petsc_gamg_setup_events[SET13]); */
1540     /* PetscLogEventRegister("GAMG: fix", PC_CLASSID, &petsc_gamg_setup_events[SET10]); */
1541     /* PetscLogEventRegister("GAMG: set levels", PC_CLASSID, &petsc_gamg_setup_events[SET11]); */
1542     /* create timer stages */
1543 #if defined GAMG_STAGES
1544     {
1545       char str[32];
1546       sprintf(str,"MG Level %d (finest)",0);
1547       PetscLogStageRegister(str, &gamg_stages[0]);
1548       PetscInt lidx;
1549       for (lidx=1;lidx<9;lidx++){
1550 	sprintf(str,"MG Level %d",lidx);
1551 	PetscLogStageRegister(str, &gamg_stages[lidx]);
1552       }
1553     }
1554 #endif
1555   }
1556 #endif
1557   /* general events */
1558 #if defined PETSC_USE_LOG
1559   PetscLogEventRegister("PCGAMGgraph_AGG", 0, &PC_GAMGGgraph_AGG);
1560   PetscLogEventRegister("PCGAMGgraph_GEO", PC_CLASSID, &PC_GAMGGgraph_GEO);
1561   PetscLogEventRegister("PCGAMGcoarse_AGG", PC_CLASSID, &PC_GAMGCoarsen_AGG);
1562   PetscLogEventRegister("PCGAMGcoarse_GEO", PC_CLASSID, &PC_GAMGCoarsen_GEO);
1563   PetscLogEventRegister("PCGAMGProl_AGG", PC_CLASSID, &PC_GAMGProlongator_AGG);
1564   PetscLogEventRegister("PCGAMGProl_GEO", PC_CLASSID, &PC_GAMGProlongator_GEO);
1565   PetscLogEventRegister("PCGAMGPOpt_AGG", PC_CLASSID, &PC_GAMGOptprol_AGG);
1566   PetscLogEventRegister("GAMGKKTProl_AGG", PC_CLASSID, &PC_GAMGKKTProl_AGG);
1567 #endif
1568 
1569   /* instantiate derived type */
1570   ierr = PetscOptionsHead("GAMG options"); CHKERRQ(ierr);
1571   {
1572     char tname[256] = GAMGAGG;
1573     ierr = PetscOptionsList("-pc_gamg_type","Type of GAMG method","PCGAMGSetType",
1574                             GAMGList, tname, tname, sizeof(tname), PETSC_NULL );
1575     CHKERRQ(ierr);
1576     ierr = PCGAMGSetType( pc, tname ); CHKERRQ(ierr);
1577   }
1578   ierr = PetscOptionsTail();   CHKERRQ(ierr);
1579 
1580   PetscFunctionReturn(0);
1581 }
1582 EXTERN_C_END
1583