xref: /petsc/src/ksp/pc/impls/gamg/gamg.c (revision 78e224df856aa9ec3fb1842e2d0dab3c0cee0b7a)
1 /*
2  GAMG geometric-algebric multiogrid PC - Mark Adams 2011
3  */
4 #include <../src/ksp/pc/impls/gamg/gamg.h>
5 
6 PetscLogEvent gamg_setup_stages[NUM_SET];
7 
8 /* Private context for the GAMG preconditioner */
9 typedef struct gamg_TAG {
10   PetscInt       m_dim;
11   PetscInt       m_Nlevels;
12   PetscInt       m_data_sz;
13   PetscInt       m_data_rows;
14   PetscInt       m_data_cols;
15   PetscBool      m_useSA;
16   PetscReal     *m_data; /* blocked vector of vertex data on fine grid (coordinates) */
17 } PC_GAMG;
18 
19 /* -------------------------------------------------------------------------- */
20 /*
21    PCSetCoordinates_GAMG
22 
23    Input Parameter:
24    .  pc - the preconditioner context
25 */
26 EXTERN_C_BEGIN
27 #undef __FUNCT__
28 #define __FUNCT__ "PCSetCoordinates_GAMG"
29 PetscErrorCode PCSetCoordinates_GAMG( PC a_pc, PetscInt a_ndm, PetscReal *a_coords )
30 {
31   PC_MG          *mg = (PC_MG*)a_pc->data;
32   PC_GAMG        *pc_gamg = (PC_GAMG*)mg->innerctx;
33   PetscErrorCode ierr;
34   PetscInt       arrsz,bs,my0,kk,ii,jj,nloc,Iend;
35   Mat            Amat = a_pc->pmat;
36   PetscBool      flag;
37   char           str[64];
38 
39   PetscFunctionBegin;
40   ierr  = MatGetBlockSize( Amat, &bs );               CHKERRQ( ierr );
41   ierr  = MatGetOwnershipRange( Amat, &my0, &Iend ); CHKERRQ(ierr);
42   nloc = (Iend-my0)/bs;
43   if((Iend-my0)%bs!=0) SETERRQ1(((PetscObject)Amat)->comm,PETSC_ERR_ARG_WRONG, "Bad local size %d.",nloc);
44 
45   ierr  = PetscOptionsGetString(PETSC_NULL,"-pc_gamg_type",str,64,&flag);    CHKERRQ( ierr );
46   pc_gamg->m_useSA = (PetscBool)(flag && strcmp(str,"sa") == 0);
47 
48   pc_gamg->m_data_rows = 1;
49   if(a_coords == 0) pc_gamg->m_useSA = PETSC_TRUE; /* use SA if no data */
50   if( !pc_gamg->m_useSA ) pc_gamg->m_data_cols = a_ndm; /* coordinates */
51   else{ /* SA: null space vectors */
52     if(a_coords != 0 && bs==1 ) pc_gamg->m_data_cols = 1; /* scalar w/ coords and SA (not needed) */
53     else if(a_coords != 0) pc_gamg->m_data_cols = (a_ndm==2 ? 3 : 6); /* elasticity */
54     else pc_gamg->m_data_cols = bs; /* no data, force SA with constant null space vectors */
55     pc_gamg->m_data_rows = bs;
56   }
57   arrsz = nloc*pc_gamg->m_data_rows*pc_gamg->m_data_cols;
58 
59   /* create data - syntactic sugar that should be refactored at some point */
60   if (!pc_gamg->m_data || (pc_gamg->m_data_sz != arrsz)) {
61     ierr = PetscFree( pc_gamg->m_data );  CHKERRQ(ierr);
62     ierr = PetscMalloc((arrsz+1)*sizeof(double), &pc_gamg->m_data ); CHKERRQ(ierr);
63   }
64   for(kk=0;kk<arrsz;kk++)pc_gamg->m_data[kk] = -999.;
65   pc_gamg->m_data[arrsz] = -99.;
66   /* copy data in - column oriented */
67   if( pc_gamg->m_useSA ) {
68     const PetscInt M = Iend - my0;
69     for(kk=0;kk<nloc;kk++){
70       PetscReal *data = &pc_gamg->m_data[kk*bs];
71       if( pc_gamg->m_data_cols==1 ) *data = 1.0;
72       else {
73         for(ii=0;ii<bs;ii++)
74 	  for(jj=0;jj<bs;jj++)
75 	    if(ii==jj)data[ii*M + jj] = 1.0; /* translational modes */
76 	    else data[ii*M + jj] = 0.0;
77         if( a_coords != 0 ) {
78           if( a_ndm == 2 ){ /* rotational modes */
79             data += 2*M;
80             data[0] = -a_coords[2*kk+1];
81             data[1] =  a_coords[2*kk];
82           }
83           else {
84             data += 3*M;
85             data[0] = 0.0;               data[M+0] =  a_coords[3*kk+2]; data[2*M+0] = -a_coords[3*kk+1];
86             data[1] = -a_coords[3*kk+2]; data[M+1] = 0.0;               data[2*M+1] =  a_coords[3*kk];
87             data[2] =  a_coords[3*kk+1]; data[M+2] = -a_coords[3*kk];   data[2*M+2] = 0.0;
88           }
89         }
90       }
91     }
92   }
93   else {
94     for( kk = 0 ; kk < nloc ; kk++ ){
95       for( ii = 0 ; ii < a_ndm ; ii++ ) {
96         pc_gamg->m_data[ii*nloc + kk] =  a_coords[kk*a_ndm + ii];
97       }
98     }
99   }
100   assert(pc_gamg->m_data[arrsz] == -99.);
101 
102   pc_gamg->m_data_sz = arrsz;
103   pc_gamg->m_dim = a_ndm;
104 
105   PetscFunctionReturn(0);
106 }
107 EXTERN_C_END
108 
109 
110 /* -----------------------------------------------------------------------------*/
111 #undef __FUNCT__
112 #define __FUNCT__ "PCReset_GAMG"
113 PetscErrorCode PCReset_GAMG(PC pc)
114 {
115   PetscErrorCode  ierr;
116   PC_MG           *mg = (PC_MG*)pc->data;
117   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
118 
119   PetscFunctionBegin;
120   ierr = PetscFree(pc_gamg->m_data);CHKERRQ(ierr);
121   pc_gamg->m_data = 0; pc_gamg->m_data_sz = 0;
122   PetscFunctionReturn(0);
123 }
124 
125 /* -------------------------------------------------------------------------- */
126 /*
127    partitionLevel
128 
129    Input Parameter:
130    . a_Amat_fine - matrix on this fine (k) level
131    . a_ndata_rows - size of data to move (coarse grid)
132    . a_ndata_cols - size of data to move (coarse grid)
133    In/Output Parameter:
134    . a_P_inout - prolongation operator to the next level (k-1)
135    . a_coarse_data - data that need to be moved
136    . a_nactive_proc - number of active procs
137    Output Parameter:
138    . a_Amat_crs - coarse matrix that is created (k-1)
139 */
140 
141 #define MIN_EQ_PROC 300
142 #define TOP_GRID_LIM 1000
143 
144 #undef __FUNCT__
145 #define __FUNCT__ "partitionLevel"
146 PetscErrorCode partitionLevel( Mat a_Amat_fine,
147                                PetscInt a_ndata_rows,
148                                PetscInt a_ndata_cols,
149 			       PetscInt a_cbs,
150                                Mat *a_P_inout,
151                                PetscReal **a_coarse_data,
152                                PetscMPIInt *a_nactive_proc,
153                                Mat *a_Amat_crs
154                                )
155 {
156   PetscErrorCode   ierr;
157   Mat              Cmat,Pnew,Pold=*a_P_inout;
158   IS               new_indices,isnum;
159   MPI_Comm         wcomm = ((PetscObject)a_Amat_fine)->comm;
160   PetscMPIInt      mype,npe;
161   PetscInt         neq,NN,Istart,Iend,Istart0,Iend0,ncrs_new;
162   PetscMPIInt      new_npe,nactive,ncrs0;
163   PetscBool        flag = PETSC_FALSE;
164 
165   PetscFunctionBegin;
166   ierr = MPI_Comm_rank( wcomm, &mype ); CHKERRQ(ierr);
167   ierr = MPI_Comm_size( wcomm, &npe );  CHKERRQ(ierr);
168   /* RAP */
169   ierr = MatPtAP( a_Amat_fine, Pold, MAT_INITIAL_MATRIX, 2.0, &Cmat ); CHKERRQ(ierr);
170 
171   ierr = MatSetBlockSize( Cmat, a_cbs );      CHKERRQ(ierr);
172   ierr = MatGetOwnershipRange( Cmat, &Istart0, &Iend0 ); CHKERRQ(ierr);
173   ncrs0 = (Iend0-Istart0)/a_cbs; assert((Iend0-Istart0)%a_cbs == 0);
174 
175   ierr  = PetscOptionsHasName(PETSC_NULL,"-pc_gamg_avoid_repartitioning",&flag);
176   CHKERRQ( ierr );
177   if( flag ) {
178     *a_Amat_crs = Cmat; /* output */
179   }
180   else {
181     /* Repartition Cmat_{k} and move colums of P^{k}_{k-1} and coordinates accordingly */
182     MatPartitioning  mpart;
183     Mat              adj;
184     const PetscInt *idx, data_sz=a_ndata_rows*a_ndata_cols;
185     const PetscInt  stride0=ncrs0*a_ndata_rows,*is_idx;
186     PetscInt         is_sz,*isnewproc_idx,ii,jj,kk,strideNew,tidx[ncrs0*data_sz];;
187     /* create sub communicator  */
188     MPI_Comm         cm,new_comm;
189     IS               isnewproc;
190     MPI_Group        wg, g2;
191     PetscMPIInt      ranks[npe],counts[npe];
192     IS               isscat;
193     PetscScalar    *array;
194     Vec             src_crd, dest_crd;
195     PetscReal      *data = *a_coarse_data;
196     VecScatter      vecscat;
197     PetscInt
198 
199     /* get number of PEs to make active, reduce */
200     ierr = MatGetSize( Cmat, &neq, &NN );CHKERRQ(ierr);
201     new_npe = neq/MIN_EQ_PROC; /* hardwire min. number of eq/proc */
202     if( new_npe == 0 || neq < TOP_GRID_LIM ) new_npe = 1;
203     else if (new_npe >= *a_nactive_proc ) new_npe = *a_nactive_proc; /* no change, rare */
204 
205     ierr = MPI_Allgather( &ncrs0, 1, MPI_INT, counts, 1, MPI_INT, wcomm ); CHKERRQ(ierr);
206     assert(counts[mype]==ncrs0);
207     /* count real active pes */
208     for( nactive = jj = 0 ; jj < npe ; jj++) {
209       if( counts[jj] != 0 ) {
210 	ranks[nactive++] = jj;
211       }
212     }
213     assert(nactive>=new_npe);
214 
215     PetscPrintf(PETSC_COMM_WORLD,"\t[%d]%s npe (active): %d --> %d. new npe = %d, neq = %d\n",mype,__FUNCT__,*a_nactive_proc,nactive,new_npe,neq);
216     *a_nactive_proc = new_npe; /* output */
217 
218     ierr = MPI_Comm_group( wcomm, &wg ); CHKERRQ(ierr);
219     ierr = MPI_Group_incl( wg, nactive, ranks, &g2 ); CHKERRQ(ierr);
220     ierr = MPI_Comm_create( wcomm, g2, &cm ); CHKERRQ(ierr);
221     if( cm != MPI_COMM_NULL ) {
222       ierr = PetscCommDuplicate( cm, &new_comm, PETSC_NULL ); CHKERRQ(ierr);
223       ierr = MPI_Comm_free( &cm );                             CHKERRQ(ierr);
224     }
225     ierr = MPI_Group_free( &wg );                            CHKERRQ(ierr);
226     ierr = MPI_Group_free( &g2 );                            CHKERRQ(ierr);
227 
228     /* MatPartitioningApply call MatConvert, which is collective */
229     ierr = PetscLogEventBegin(gamg_setup_stages[SET12],0,0,0,0);CHKERRQ(ierr);
230     if( a_cbs == 1) {
231       ierr = MatConvert( Cmat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
232     }
233     else{
234       /* make a scalar matrix to partition */
235       Mat tMat;
236       PetscInt ncols; const PetscScalar *vals; const PetscInt *idx;
237       MatInfo info;
238       ierr = MatGetInfo(Cmat,MAT_LOCAL,&info); CHKERRQ(ierr);
239       ncols = (PetscInt)info.nz_used/((ncrs0+1)*a_cbs*a_cbs)+1;
240 
241       ierr = MatCreateMPIAIJ( wcomm, ncrs0, ncrs0,
242                               PETSC_DETERMINE, PETSC_DETERMINE,
243                               2*ncols, PETSC_NULL, ncols, PETSC_NULL,
244                               &tMat );
245       CHKERRQ(ierr);
246 
247       for ( ii = Istart0; ii < Iend0; ii++ ) {
248         PetscInt dest_row = ii/a_cbs;
249         ierr = MatGetRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
250         for( jj = 0 ; jj < ncols ; jj++ ){
251           PetscInt dest_col = idx[jj]/a_cbs;
252           PetscScalar v = 1.0;
253           ierr = MatSetValues(tMat,1,&dest_row,1,&dest_col,&v,ADD_VALUES); CHKERRQ(ierr);
254         }
255         ierr = MatRestoreRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
256       }
257       ierr = MatAssemblyBegin(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
258       ierr = MatAssemblyEnd(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
259 
260       ierr = MatConvert( tMat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
261 
262       ierr = MatDestroy( &tMat );  CHKERRQ(ierr);
263     }
264 
265     if( ncrs0 != 0 ){
266       /* hack to fix global data that pmetis.c uses in 'adj' */
267       for( nactive = jj = 0 ; jj < npe ; jj++ ) {
268 	if( counts[jj] != 0 ) {
269 	  adj->rmap->range[nactive++] = adj->rmap->range[jj];
270 	}
271       }
272       adj->rmap->range[nactive] = adj->rmap->range[npe];
273 
274       ierr = MatPartitioningCreate( new_comm, &mpart ); CHKERRQ(ierr);
275       ierr = MatPartitioningSetAdjacency( mpart, adj ); CHKERRQ(ierr);
276       ierr = MatPartitioningSetFromOptions( mpart );    CHKERRQ(ierr);
277       ierr = MatPartitioningSetNParts( mpart, new_npe );CHKERRQ(ierr);
278       ierr = MatPartitioningApply( mpart, &isnewproc ); CHKERRQ(ierr);
279       ierr = MatPartitioningDestroy( &mpart );          CHKERRQ(ierr);
280 
281       /* collect IS info */
282       ierr = ISGetLocalSize( isnewproc, &is_sz );        CHKERRQ(ierr);
283       ierr = PetscMalloc( a_cbs*is_sz*sizeof(PetscInt), &isnewproc_idx ); CHKERRQ(ierr);
284       ierr = ISGetIndices( isnewproc, &is_idx );     CHKERRQ(ierr);
285       /* spread partitioning across machine - probably the right thing to do but machine spec. */
286       NN = npe/new_npe;
287       for(kk=0,jj=0;kk<is_sz;kk++){
288         for(ii=0 ; ii<a_cbs ; ii++, jj++ ) {
289           isnewproc_idx[jj] = is_idx[kk] * NN; /* distribution */
290         }
291       }
292       ierr = ISRestoreIndices( isnewproc, &is_idx );     CHKERRQ(ierr);
293       ierr = ISDestroy( &isnewproc );                    CHKERRQ(ierr);
294       is_sz *= a_cbs;
295 
296       ierr = MPI_Comm_free( &new_comm );    CHKERRQ(ierr);
297     }
298     else{
299       isnewproc_idx = 0;
300       is_sz = 0;
301     }
302     ierr = MatDestroy( &adj );                       CHKERRQ(ierr);
303     ierr = ISCreateGeneral( wcomm, is_sz, isnewproc_idx, PETSC_COPY_VALUES, &isnewproc );
304     if( isnewproc_idx != 0 ) {
305       ierr = PetscFree( isnewproc_idx );  CHKERRQ(ierr);
306     }
307 
308     /*
309      Create an index set from the isnewproc index set to indicate the mapping TO
310      */
311     ierr = ISPartitioningToNumbering( isnewproc, &isnum ); CHKERRQ(ierr);
312     /*
313      Determine how many elements are assigned to each processor
314      */
315     ierr = ISPartitioningCount( isnewproc, npe, counts ); CHKERRQ(ierr);
316     ierr = ISDestroy( &isnewproc );                       CHKERRQ(ierr);
317     ncrs_new = counts[mype]/a_cbs;
318     strideNew = ncrs_new*a_ndata_rows;
319     ierr = PetscLogEventEnd(gamg_setup_stages[SET12],0,0,0,0);   CHKERRQ(ierr);
320 
321     /* Create a vector to contain the newly ordered element information */
322     ierr = VecCreate( wcomm, &dest_crd );
323     ierr = VecSetSizes( dest_crd, data_sz*ncrs_new, PETSC_DECIDE ); CHKERRQ(ierr);
324     ierr = VecSetFromOptions( dest_crd ); CHKERRQ(ierr); /*funny vector-get global options?*/
325     /*
326       There are 'a_ndata_rows*a_ndata_cols' data items per node, (one can think of the vectors of having
327       a block size of ...).  Note, ISs are expanded into equation space by 'a_cbs'.
328     */
329     ierr = ISGetIndices( isnum, &idx ); CHKERRQ(ierr);
330     for(ii=0,jj=0; ii<ncrs0 ; ii++) {
331       PetscInt id = idx[ii*a_cbs]/a_cbs; /* get node back */
332       for( kk=0; kk<data_sz ; kk++, jj++) tidx[jj] = id*data_sz + kk;
333     }
334     ierr = ISRestoreIndices( isnum, &idx ); CHKERRQ(ierr);
335     ierr = ISCreateGeneral( wcomm, data_sz*ncrs0, tidx, PETSC_COPY_VALUES, &isscat );
336     CHKERRQ(ierr);
337     /*
338       Create a vector to contain the original vertex information for each element
339     */
340     ierr = VecCreateSeq( PETSC_COMM_SELF, data_sz*ncrs0, &src_crd ); CHKERRQ(ierr);
341     for( jj=0; jj<a_ndata_cols ; jj++ ) {
342       for( ii=0 ; ii<ncrs0 ; ii++) {
343 	for( kk=0; kk<a_ndata_rows ; kk++ ) {
344 	  PetscInt ix = ii*a_ndata_rows + kk + jj*stride0, jx = ii*data_sz + kk*a_ndata_cols + jj;
345 	  ierr = VecSetValues( src_crd, 1, &jx, &data[ix], INSERT_VALUES );  CHKERRQ(ierr);
346 	}
347       }
348     }
349     ierr = VecAssemblyBegin(src_crd); CHKERRQ(ierr);
350     ierr = VecAssemblyEnd(src_crd); CHKERRQ(ierr);
351     /*
352       Scatter the element vertex information (still in the original vertex ordering)
353       to the correct processor
354     */
355     ierr = VecScatterCreate( src_crd, PETSC_NULL, dest_crd, isscat, &vecscat);
356     CHKERRQ(ierr);
357     ierr = ISDestroy( &isscat );       CHKERRQ(ierr);
358     ierr = VecScatterBegin(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
359     ierr = VecScatterEnd(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
360     ierr = VecScatterDestroy( &vecscat );       CHKERRQ(ierr);
361     ierr = VecDestroy( &src_crd );       CHKERRQ(ierr);
362     /*
363       Put the element vertex data into a new allocation of the gdata->ele
364     */
365     ierr = PetscFree( *a_coarse_data );    CHKERRQ(ierr);
366     ierr = PetscMalloc( data_sz*ncrs_new*sizeof(PetscReal), a_coarse_data );    CHKERRQ(ierr);
367 
368     ierr = VecGetArray( dest_crd, &array );    CHKERRQ(ierr);
369     data = *a_coarse_data;
370     for( jj=0; jj<a_ndata_cols ; jj++ ) {
371       for( ii=0 ; ii<ncrs_new ; ii++) {
372 	for( kk=0; kk<a_ndata_rows ; kk++ ) {
373 	  PetscInt ix = ii*a_ndata_rows + kk + jj*strideNew, jx = ii*data_sz + kk*a_ndata_cols + jj;
374 	  data[ix] = PetscRealPart(array[jx]);
375 	  array[jx] = 1.e300;
376 	}
377       }
378     }
379     ierr = VecRestoreArray( dest_crd, &array );    CHKERRQ(ierr);
380     ierr = VecDestroy( &dest_crd );    CHKERRQ(ierr);
381 
382     /*
383       Invert for MatGetSubMatrix
384     */
385     ierr = ISInvertPermutation( isnum, ncrs_new*a_cbs, &new_indices ); CHKERRQ(ierr);
386     ierr = ISSort( new_indices ); CHKERRQ(ierr); /* is this needed? */
387     ierr = ISDestroy( &isnum ); CHKERRQ(ierr);
388     /* A_crs output */
389     ierr = MatGetSubMatrix( Cmat, new_indices, new_indices, MAT_INITIAL_MATRIX, a_Amat_crs );
390     CHKERRQ(ierr);
391 
392     ierr = MatDestroy( &Cmat ); CHKERRQ(ierr);
393     Cmat = *a_Amat_crs; /* output */
394     ierr = MatSetBlockSize( Cmat, a_cbs );      CHKERRQ(ierr);
395 
396     /* prolongator */
397     ierr = MatGetOwnershipRange( Pold, &Istart, &Iend );    CHKERRQ(ierr);
398     {
399       IS findices;
400       ierr = ISCreateStride(wcomm,Iend-Istart,Istart,1,&findices);   CHKERRQ(ierr);
401       ierr = MatGetSubMatrix( Pold, findices, new_indices, MAT_INITIAL_MATRIX, &Pnew );
402       CHKERRQ(ierr);
403       ierr = ISDestroy( &findices ); CHKERRQ(ierr);
404     }
405     ierr = MatDestroy( a_P_inout ); CHKERRQ(ierr);
406     *a_P_inout = Pnew; /* output */
407     ierr = ISDestroy( &new_indices ); CHKERRQ(ierr);
408   }
409 
410   PetscFunctionReturn(0);
411 }
412 
413 #define GAMG_MAXLEVELS 30
414 #if defined(PETSC_USE_LOG)
415 PetscLogStage  gamg_stages[20];
416 #endif
417 /* -------------------------------------------------------------------------- */
418 /*
419    PCSetUp_GAMG - Prepares for the use of the GAMG preconditioner
420                     by setting data structures and options.
421 
422    Input Parameter:
423 .  pc - the preconditioner context
424 
425    Application Interface Routine: PCSetUp()
426 
427    Notes:
428    The interface routine PCSetUp() is not usually called directly by
429    the user, but instead is called by PCApply() if necessary.
430 */
431 #undef __FUNCT__
432 #define __FUNCT__ "PCSetUp_GAMG"
433 PetscErrorCode PCSetUp_GAMG( PC a_pc )
434 {
435   PetscErrorCode  ierr;
436   PC_MG           *mg = (PC_MG*)a_pc->data;
437   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
438   Mat              Amat = a_pc->mat, Pmat = a_pc->pmat;
439   PetscInt         fine_level, level, level1, M, N, bs, nloc, lidx, Istart, Iend;
440   MPI_Comm         wcomm = ((PetscObject)a_pc)->comm;
441   PetscMPIInt      mype,npe,nactivepe;
442   PetscBool        isOK;
443   Mat              Aarr[GAMG_MAXLEVELS], Parr[GAMG_MAXLEVELS];
444   PetscReal       *coarse_data = 0, *data, emaxs[GAMG_MAXLEVELS];
445   MatInfo          info;
446 
447   PetscFunctionBegin;
448   if( a_pc->setupcalled ) {
449     /* no state data in GAMG to destroy */
450     ierr = PCReset_MG( a_pc ); CHKERRQ(ierr);
451   }
452   ierr = MPI_Comm_rank(wcomm,&mype);CHKERRQ(ierr);
453   ierr = MPI_Comm_size(wcomm,&npe);CHKERRQ(ierr);
454   /* GAMG requires input of fine-grid matrix. It determines nlevels. */
455   ierr = MatGetBlockSize( Amat, &bs ); CHKERRQ(ierr);
456   ierr = MatGetSize( Amat, &M, &N );CHKERRQ(ierr);
457   ierr = MatGetOwnershipRange( Amat, &Istart, &Iend ); CHKERRQ(ierr);
458   nloc = (Iend-Istart)/bs; assert((Iend-Istart)%bs == 0);
459 
460   /* get data of not around */
461   if( pc_gamg->m_data == 0 && nloc > 0 ) {
462     ierr  = PCSetCoordinates_GAMG( a_pc, -1, 0 );    CHKERRQ( ierr );
463   }
464   data = pc_gamg->m_data;
465 
466   /* Get A_i and R_i */
467   ierr = MatGetInfo(Amat,MAT_GLOBAL_SUM,&info); CHKERRQ(ierr);
468   PetscPrintf(PETSC_COMM_WORLD,"\t[%d]%s level %d N=%d, n data rows=%d, n data cols=%d, nnz/row (ave)=%d, np=%d\n",
469 	      mype,__FUNCT__,0,N,pc_gamg->m_data_rows,pc_gamg->m_data_cols,(PetscInt)(info.nz_used/(PetscReal)N),npe);
470   for ( level=0, Aarr[0] = Pmat, nactivepe = npe; /* hard wired stopping logic */
471         level < GAMG_MAXLEVELS-1 && (level==0 || M>TOP_GRID_LIM) && (npe==1 || nactivepe>1);
472         level++ ){
473     level1 = level + 1;
474     ierr = PetscLogEventBegin(gamg_setup_stages[SET1],0,0,0,0);CHKERRQ(ierr);
475     ierr = createProlongation(Aarr[level], data, pc_gamg->m_dim, pc_gamg->m_data_cols, pc_gamg->m_useSA,
476                               level, &bs, &Parr[level1], &coarse_data, &isOK, &emaxs[level] );
477     CHKERRQ(ierr);
478     ierr = PetscFree( data ); CHKERRQ( ierr );
479     ierr = PetscLogEventEnd(gamg_setup_stages[SET1],0,0,0,0);CHKERRQ(ierr);
480 
481     if(level==0) Aarr[0] = Amat; /* use Pmat for finest level setup, but use mat for solver */
482 
483     if( isOK ) {
484       ierr = PetscLogEventBegin(gamg_setup_stages[SET2],0,0,0,0);CHKERRQ(ierr);
485       ierr = partitionLevel( Aarr[level], pc_gamg->m_useSA ? bs : 1, pc_gamg->m_data_cols, bs,
486                              &Parr[level1], &coarse_data, &nactivepe, &Aarr[level1] );
487       CHKERRQ(ierr);
488       ierr = PetscLogEventEnd(gamg_setup_stages[SET2],0,0,0,0);CHKERRQ(ierr);
489       ierr = MatGetSize( Aarr[level1], &M, &N );CHKERRQ(ierr);
490       ierr = MatGetInfo(Aarr[level1],MAT_GLOBAL_SUM,&info); CHKERRQ(ierr);
491       PetscPrintf(PETSC_COMM_WORLD,"\t\t[%d]%s %d) N=%d, bs=%d, n data cols=%d, nnz/row (ave)=%d, %d active pes\n",
492 		  mype,__FUNCT__,level1,N,bs,pc_gamg->m_data_cols,(PetscInt)(info.nz_used/(PetscReal)N),nactivepe);
493       /* coarse grids with SA can have zero row/cols from singleton aggregates */
494       /* aggregation method can probably gaurrentee this does not happen! - be safe for now */
495 
496       if( PETSC_TRUE ){
497         Vec diag; PetscScalar *data_arr,v; PetscInt Istart,Iend,kk,nloceq,id;
498         v = 1.e-10; /* LU factor has hard wired numbers for small diags so this needs to match (yuk) */
499         ierr = MatGetOwnershipRange(Aarr[level1], &Istart, &Iend); CHKERRQ(ierr);
500         nloceq = Iend-Istart;
501         ierr = MatGetVecs( Aarr[level1], &diag, 0 );    CHKERRQ(ierr);
502         ierr = MatGetDiagonal( Aarr[level1], diag );    CHKERRQ(ierr);
503         ierr = VecGetArray( diag, &data_arr );   CHKERRQ(ierr);
504         for(kk=0;kk<nloceq;kk++){
505           if(data_arr[kk]==0.0) {
506             id = kk + Istart;
507             ierr = MatSetValues(Aarr[level1],1,&id,1,&id,&v,INSERT_VALUES);
508             CHKERRQ(ierr);
509             PetscPrintf(PETSC_COMM_SELF,"\t[%d]%s warning: added diag to zero (%d) on level %d \n",mype,__FUNCT__,id,level);
510           }
511         }
512         ierr = VecRestoreArray( diag, &data_arr ); CHKERRQ(ierr);
513         ierr = VecDestroy( &diag );                CHKERRQ(ierr);
514         ierr = MatAssemblyBegin(Aarr[level1],MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
515         ierr = MatAssemblyEnd(Aarr[level1],MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
516       }
517     }
518     else{
519       coarse_data = 0;
520       break;
521     }
522     data = coarse_data;
523   }
524   if( coarse_data ) {
525     ierr = PetscFree( coarse_data ); CHKERRQ( ierr );
526   }
527   PetscPrintf(PETSC_COMM_WORLD,"\t[%d]%s %d levels\n",0,__FUNCT__,level + 1);
528   pc_gamg->m_data = 0; /* destroyed coordinate data */
529   pc_gamg->m_Nlevels = level + 1;
530   fine_level = level;
531   ierr = PCMGSetLevels(a_pc,pc_gamg->m_Nlevels,PETSC_NULL);CHKERRQ(ierr);
532 
533   /* set default smoothers */
534   for ( lidx=1, level = pc_gamg->m_Nlevels-2;
535         lidx <= fine_level;
536         lidx++, level--) {
537     PetscReal emax, emin;
538     KSP smoother; PC subpc;
539     ierr = PCMGGetSmoother( a_pc, lidx, &smoother ); CHKERRQ(ierr);
540     ierr = KSPSetType( smoother, KSPCHEBYCHEV );CHKERRQ(ierr);
541     if( emaxs[level] > 0.0 ) emax=emaxs[level];
542     else{ /* eigen estimate 'emax' */
543       KSP eksp; Mat Lmat = Aarr[level];
544       Vec bb, xx; PC pc;
545 
546       ierr = MatGetVecs( Lmat, &bb, 0 );         CHKERRQ(ierr);
547       ierr = MatGetVecs( Lmat, &xx, 0 );         CHKERRQ(ierr);
548       {
549 	PetscRandom    rctx;
550 	ierr = PetscRandomCreate(wcomm,&rctx);CHKERRQ(ierr);
551 	ierr = PetscRandomSetFromOptions(rctx);CHKERRQ(ierr);
552 	ierr = VecSetRandom(bb,rctx);CHKERRQ(ierr);
553 	ierr = PetscRandomDestroy( &rctx ); CHKERRQ(ierr);
554       }
555       ierr = KSPCreate(wcomm,&eksp);CHKERRQ(ierr);
556       ierr = KSPSetType( eksp, KSPCG );                      CHKERRQ(ierr);
557       ierr = KSPSetInitialGuessNonzero( eksp, PETSC_FALSE ); CHKERRQ(ierr);
558       ierr = KSPSetOperators( eksp, Lmat, Lmat, DIFFERENT_NONZERO_PATTERN ); CHKERRQ( ierr );
559       ierr = KSPGetPC( eksp, &pc );CHKERRQ( ierr );
560       ierr = PCSetType( pc, PCPBJACOBI ); CHKERRQ(ierr); /* should be same as above */
561       ierr = KSPSetTolerances( eksp, PETSC_DEFAULT, PETSC_DEFAULT, PETSC_DEFAULT, 10 );
562       CHKERRQ(ierr);
563       //ierr = KSPSetConvergenceTest( eksp, KSPSkipConverged, 0, 0 ); CHKERRQ(ierr);
564       ierr = KSPSetNormType( eksp, KSP_NORM_NONE );                 CHKERRQ(ierr);
565 
566       ierr = KSPSetComputeSingularValues( eksp,PETSC_TRUE ); CHKERRQ(ierr);
567       ierr = KSPSolve( eksp, bb, xx ); CHKERRQ(ierr);
568       ierr = KSPComputeExtremeSingularValues( eksp, &emax, &emin ); CHKERRQ(ierr);
569       ierr = VecDestroy( &xx );       CHKERRQ(ierr);
570       ierr = VecDestroy( &bb );       CHKERRQ(ierr);
571       ierr = KSPDestroy( &eksp );       CHKERRQ(ierr);
572       PetscPrintf(PETSC_COMM_WORLD,"\t\t\t%s max eigen=%e min=%e PC=%s\n",__FUNCT__,emax,emin,PETSC_GAMG_SMOOTHER);
573     }
574     {
575       PetscInt N1, N0, tt;
576       ierr = MatGetSize( Aarr[level], &N1, &tt );         CHKERRQ(ierr);
577       ierr = MatGetSize( Aarr[level+1], &N0, &tt );       CHKERRQ(ierr);
578       emin = 1.*emax/((PetscReal)N1/(PetscReal)N0); /* this should be about the coarsening rate */
579       emax *= 1.05;
580 
581     }
582 
583     ierr = KSPSetOperators( smoother, Aarr[level], Aarr[level], DIFFERENT_NONZERO_PATTERN );
584     ierr = KSPChebychevSetEigenvalues( smoother, emax, emin );CHKERRQ(ierr);
585     /*ierr = KSPSetTolerances(smoother,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT,2); CHKERRQ(ierr);*/
586     ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
587     ierr = PCSetType( subpc, PETSC_GAMG_SMOOTHER ); CHKERRQ(ierr);
588     ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
589   }
590   {
591     KSP smoother; /* coarse grid */
592     Mat Lmat = Aarr[pc_gamg->m_Nlevels-1];
593     ierr = PCMGGetSmoother( a_pc, 0, &smoother ); CHKERRQ(ierr);
594     ierr = KSPSetOperators( smoother, Lmat, Lmat, DIFFERENT_NONZERO_PATTERN );
595     CHKERRQ(ierr);
596     ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
597   }
598 
599   /* should be called in PCSetFromOptions_GAMG(), but cannot be called prior to PCMGSetLevels() */
600   ierr = PCSetFromOptions_MG(a_pc); CHKERRQ(ierr);
601   {
602     PetscBool galerkin;
603     ierr = PCMGGetGalerkin( a_pc,  &galerkin); CHKERRQ(ierr);
604     if(galerkin){
605       SETERRQ(wcomm,PETSC_ERR_ARG_WRONG, "GAMG does galerkin manually so it must not be used in PC_MG.");
606     }
607   }
608 
609   /* set interpolation between the levels, create timer stages, clean up */
610   if( PETSC_FALSE ) {
611     char str[32];
612     sprintf(str,"MG Level %d (%d)",0,pc_gamg->m_Nlevels-1);
613     PetscLogStageRegister(str, &gamg_stages[fine_level]);
614   }
615   for (lidx=0,level=pc_gamg->m_Nlevels-1;
616        lidx<fine_level;
617        lidx++, level--){
618     ierr = PCMGSetInterpolation( a_pc, lidx+1, Parr[level] );CHKERRQ(ierr);
619     if( !PETSC_TRUE ) {
620       PetscViewer viewer; char fname[32];
621       sprintf(fname,"Pmat_%d.m",level);
622       ierr = PetscViewerASCIIOpen( wcomm, fname, &viewer );  CHKERRQ(ierr);
623       ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
624       ierr = MatView( Parr[level], viewer ); CHKERRQ(ierr);
625       ierr = PetscViewerDestroy( &viewer );
626       sprintf(fname,"Amat_%d.m",level);
627       ierr = PetscViewerASCIIOpen( wcomm, fname, &viewer );  CHKERRQ(ierr);
628       ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
629       ierr = MatView( Aarr[level], viewer ); CHKERRQ(ierr);
630       ierr = PetscViewerDestroy( &viewer );
631     }
632     ierr = MatDestroy( &Parr[level] );  CHKERRQ(ierr);
633     ierr = MatDestroy( &Aarr[level] );  CHKERRQ(ierr);
634     if( PETSC_FALSE ) {
635       char str[32];
636       sprintf(str,"MG Level %d (%d)",lidx+1,level-1);
637       PetscLogStageRegister(str, &gamg_stages[level-1]);
638     }
639   }
640 
641   /* setupcalled is set to 0 so that MG is setup from scratch */
642   a_pc->setupcalled = 0;
643   ierr = PCSetUp_MG(a_pc);CHKERRQ(ierr);
644 
645   PetscFunctionReturn(0);
646 }
647 
648 /* ------------------------------------------------------------------------- */
649 /*
650    PCDestroy_GAMG - Destroys the private context for the GAMG preconditioner
651    that was created with PCCreate_GAMG().
652 
653    Input Parameter:
654 .  pc - the preconditioner context
655 
656    Application Interface Routine: PCDestroy()
657 */
658 #undef __FUNCT__
659 #define __FUNCT__ "PCDestroy_GAMG"
660 PetscErrorCode PCDestroy_GAMG(PC pc)
661 {
662   PetscErrorCode  ierr;
663   PC_MG           *mg = (PC_MG*)pc->data;
664   PC_GAMG         *pc_gamg= (PC_GAMG*)mg->innerctx;
665 
666   PetscFunctionBegin;
667   ierr = PCReset_GAMG(pc);CHKERRQ(ierr);
668   ierr = PetscFree(pc_gamg);CHKERRQ(ierr);
669   ierr = PCDestroy_MG(pc);CHKERRQ(ierr);
670   PetscFunctionReturn(0);
671 }
672 
673 #undef __FUNCT__
674 #define __FUNCT__ "PCSetFromOptions_GAMG"
675 PetscErrorCode PCSetFromOptions_GAMG(PC pc)
676 {
677   /* PetscErrorCode  ierr; */
678   /* PC_MG           *mg = (PC_MG*)pc->data; */
679   /* PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx; */
680   /* MPI_Comm        comm = ((PetscObject)pc)->comm; */
681 
682   PetscFunctionBegin;
683   PetscFunctionReturn(0);
684 }
685 
686 /* -------------------------------------------------------------------------- */
687 /*
688  PCCreate_GAMG - Creates a GAMG preconditioner context, PC_GAMG
689 
690    Input Parameter:
691 .  pc - the preconditioner context
692 
693    Application Interface Routine: PCCreate()
694 
695   */
696  /* MC
697      PCGAMG - Use algebraic multigrid preconditioning. This preconditioner requires you provide
698        fine grid discretization matrix and coordinates on the fine grid.
699 
700    Options Database Key:
701    Multigrid options(inherited)
702 +  -pc_mg_cycles <1>: 1 for V cycle, 2 for W-cycle (MGSetCycles)
703 .  -pc_mg_smoothup <1>: Number of post-smoothing steps (MGSetNumberSmoothUp)
704 .  -pc_mg_smoothdown <1>: Number of pre-smoothing steps (MGSetNumberSmoothDown)
705    -pc_mg_type <multiplicative>: (one of) additive multiplicative full cascade kascade
706    GAMG options:
707 
708    Level: intermediate
709   Concepts: multigrid
710 
711 .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC, PCMGType,
712            PCMGSetLevels(), PCMGGetLevels(), PCMGSetType(), MPSetCycles(), PCMGSetNumberSmoothDown(),
713            PCMGSetNumberSmoothUp(), PCMGGetCoarseSolve(), PCMGSetResidual(), PCMGSetInterpolation(),
714            PCMGSetRestriction(), PCMGGetSmoother(), PCMGGetSmootherUp(), PCMGGetSmootherDown(),
715            PCMGSetCyclesOnLevel(), PCMGSetRhs(), PCMGSetX(), PCMGSetR()
716 M */
717 
718 EXTERN_C_BEGIN
719 #undef __FUNCT__
720 #define __FUNCT__ "PCCreate_GAMG"
721 PetscErrorCode  PCCreate_GAMG(PC pc)
722 {
723   PetscErrorCode  ierr;
724   PC_GAMG         *pc_gamg;
725   PC_MG           *mg;
726   PetscClassId     cookie;
727 
728   PetscFunctionBegin;
729   /* PCGAMG is an inherited class of PCMG. Initialize pc as PCMG */
730   ierr = PCSetType(pc,PCMG);CHKERRQ(ierr); /* calls PCCreate_MG() and MGCreate_Private() */
731   ierr = PetscObjectChangeTypeName((PetscObject)pc,PCGAMG);CHKERRQ(ierr);
732 
733   /* create a supporting struct and attach it to pc */
734   ierr = PetscNewLog(pc,PC_GAMG,&pc_gamg);CHKERRQ(ierr);
735   mg = (PC_MG*)pc->data;
736   mg->innerctx = pc_gamg;
737 
738   pc_gamg->m_Nlevels    = -1;
739 
740   /* overwrite the pointers of PCMG by the functions of PCGAMG */
741   pc->ops->setfromoptions = PCSetFromOptions_GAMG;
742   pc->ops->setup          = PCSetUp_GAMG;
743   pc->ops->reset          = PCReset_GAMG;
744   pc->ops->destroy        = PCDestroy_GAMG;
745 
746   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
747 					    "PCSetCoordinates_C",
748 					    "PCSetCoordinates_GAMG",
749 					    PCSetCoordinates_GAMG);CHKERRQ(ierr);
750   static int count = 0;
751   if( count++ == 0 ) {
752     PetscClassIdRegister("GAMG Setup",&cookie);
753     PetscLogEventRegister("GAMG: createProl", cookie, &gamg_setup_stages[SET1]);
754     PetscLogEventRegister(" make graph", cookie, &gamg_setup_stages[SET3]);
755     PetscLogEventRegister(" MIS/Agg", cookie, &gamg_setup_stages[SET4]);
756     PetscLogEventRegister("  geo: growSupp", cookie, &gamg_setup_stages[SET5]);
757     PetscLogEventRegister("  geo: triangle", cookie, &gamg_setup_stages[SET6]);
758     PetscLogEventRegister("   search & set", cookie, &gamg_setup_stages[FIND_V]);
759     PetscLogEventRegister("  SA: init", cookie, &gamg_setup_stages[SET7]);
760     /* PetscLogEventRegister("  SA: frmProl0", cookie, &gamg_setup_stages[SET8]); */
761     PetscLogEventRegister("  SA: smooth", cookie, &gamg_setup_stages[SET9]);
762     PetscLogEventRegister("GAMG: partLevel", cookie, &gamg_setup_stages[SET2]);
763     PetscLogEventRegister(" PL repartition", cookie, &gamg_setup_stages[SET12]);
764     /* PetscLogEventRegister(" PL move data", cookie, &gamg_setup_stages[SET13]); */
765     /* PetscLogEventRegister("GAMG: fix", cookie, &gamg_setup_stages[SET10]); */
766     /* PetscLogEventRegister("GAMG: set levels", cookie, &gamg_setup_stages[SET11]); */
767   }
768 
769   PetscFunctionReturn(0);
770 }
771 EXTERN_C_END
772