xref: /petsc/src/ksp/pc/impls/gamg/gamg.c (revision 093de6efe177a7c32696e070950bee55f3e0e99c)
1 /*
2  GAMG geometric-algebric multiogrid PC - Mark Adams 2011
3  */
4 #include <../src/ksp/pc/impls/gamg/gamg.h>           /*I "petscpc.h" I*/
5 #include "private/matimpl.h"
6 
7 #if defined PETSC_USE_LOG
8 PetscLogEvent gamg_setup_events[NUM_SET];
9 #endif
10 #define GAMG_MAXLEVELS 30
11 
12 /*#define GAMG_STAGES*/
13 #if (defined PETSC_USE_LOG && defined GAMG_STAGES)
14 static PetscLogStage gamg_stages[GAMG_MAXLEVELS];
15 #endif
16 
17 /* Private context for the GAMG preconditioner */
18 static PetscBool s_avoid_repart = PETSC_FALSE;
19 static PetscInt s_min_eq_proc = 600;
20 static PetscReal s_threshold = 0.05;
21 typedef struct gamg_TAG {
22   PetscInt       m_dim;
23   PetscInt       m_Nlevels;
24   PetscInt       m_data_sz;
25   PetscInt       m_data_rows;
26   PetscInt       m_data_cols;
27   PetscInt       m_count;
28   PetscInt       m_method; /* 0: geomg; 1: plain agg 'pa'; 2: smoothed agg 'sa' */
29   PetscReal     *m_data; /* blocked vector of vertex data on fine grid (coordinates) */
30   char           m_type[64];
31 } PC_GAMG;
32 
33 /* -------------------------------------------------------------------------- */
34 /*
35    PCSetCoordinates_GAMG
36 
37    Input Parameter:
38    .  pc - the preconditioner context
39 */
40 EXTERN_C_BEGIN
41 #undef __FUNCT__
42 #define __FUNCT__ "PCSetCoordinates_GAMG"
43 PetscErrorCode PCSetCoordinates_GAMG( PC a_pc, PetscInt a_ndm, PetscReal *a_coords )
44 {
45   PC_MG          *mg = (PC_MG*)a_pc->data;
46   PC_GAMG        *pc_gamg = (PC_GAMG*)mg->innerctx;
47   PetscErrorCode ierr;
48   PetscInt       arrsz,bs,my0,kk,ii,jj,nloc,Iend;
49   Mat            Amat = a_pc->pmat;
50 
51   PetscFunctionBegin;
52   PetscValidHeaderSpecific( Amat, MAT_CLASSID, 1 );
53   ierr  = MatGetBlockSize( Amat, &bs );               CHKERRQ( ierr );
54   ierr  = MatGetOwnershipRange( Amat, &my0, &Iend ); CHKERRQ(ierr);
55   nloc = (Iend-my0)/bs;
56   if((Iend-my0)%bs!=0) SETERRQ1(((PetscObject)Amat)->comm,PETSC_ERR_ARG_WRONG, "Bad local size %d.",nloc);
57 
58   pc_gamg->m_data_rows = 1;
59   if(a_coords==0 && pc_gamg->m_method==0) pc_gamg->m_method = 2; /* use SA if no coords */
60   if( pc_gamg->m_method==0 ) pc_gamg->m_data_cols = a_ndm; /* coordinates */
61   else{ /* SA: null space vectors */
62     if(a_coords != 0 && bs==1 ) pc_gamg->m_data_cols = 1; /* scalar w/ coords and SA (not needed) */
63     else if(a_coords != 0 ) pc_gamg->m_data_cols = (a_ndm==2 ? 3 : 6); /* elasticity */
64     else pc_gamg->m_data_cols = bs; /* no data, force SA with constant null space vectors */
65     pc_gamg->m_data_rows = bs;
66   }
67   arrsz = nloc*pc_gamg->m_data_rows*pc_gamg->m_data_cols;
68 
69   /* create data - syntactic sugar that should be refactored at some point */
70   if (pc_gamg->m_data==0 || (pc_gamg->m_data_sz != arrsz)) {
71     ierr = PetscFree( pc_gamg->m_data );  CHKERRQ(ierr);
72     ierr = PetscMalloc((arrsz+1)*sizeof(double), &pc_gamg->m_data ); CHKERRQ(ierr);
73   }
74   for(kk=0;kk<arrsz;kk++)pc_gamg->m_data[kk] = -999.;
75   pc_gamg->m_data[arrsz] = -99.;
76   /* copy data in - column oriented */
77   if( pc_gamg->m_method != 0 ) {
78     const PetscInt M = Iend - my0;
79     for(kk=0;kk<nloc;kk++){
80       PetscReal *data = &pc_gamg->m_data[kk*bs];
81       if( pc_gamg->m_data_cols==1 ) *data = 1.0;
82       else {
83         for(ii=0;ii<bs;ii++)
84 	  for(jj=0;jj<bs;jj++)
85 	    if(ii==jj)data[ii*M + jj] = 1.0; /* translational modes */
86 	    else data[ii*M + jj] = 0.0;
87         if( a_coords != 0 ) {
88           if( a_ndm == 2 ){ /* rotational modes */
89             data += 2*M;
90             data[0] = -a_coords[2*kk+1];
91             data[1] =  a_coords[2*kk];
92           }
93           else {
94             data += 3*M;
95             data[0] = 0.0;               data[M+0] =  a_coords[3*kk+2]; data[2*M+0] = -a_coords[3*kk+1];
96             data[1] = -a_coords[3*kk+2]; data[M+1] = 0.0;               data[2*M+1] =  a_coords[3*kk];
97             data[2] =  a_coords[3*kk+1]; data[M+2] = -a_coords[3*kk];   data[2*M+2] = 0.0;
98           }
99         }
100       }
101     }
102   }
103   else {
104     for( kk = 0 ; kk < nloc ; kk++ ){
105       for( ii = 0 ; ii < a_ndm ; ii++ ) {
106         pc_gamg->m_data[ii*nloc + kk] =  a_coords[kk*a_ndm + ii];
107       }
108     }
109   }
110   assert(pc_gamg->m_data[arrsz] == -99.);
111 
112   pc_gamg->m_data_sz = arrsz;
113   pc_gamg->m_dim = a_ndm;
114 
115   PetscFunctionReturn(0);
116 }
117 EXTERN_C_END
118 
119 
120 /* ----------------------------------------------------------------------------- */
121 #undef __FUNCT__
122 #define __FUNCT__ "PCReset_GAMG"
123 PetscErrorCode PCReset_GAMG(PC pc)
124 {
125   PetscErrorCode  ierr;
126   PC_MG           *mg = (PC_MG*)pc->data;
127   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
128 
129   PetscFunctionBegin;
130   if( pc_gamg->m_data != 0 ) { /* this should not happen, cleaned up in SetUp */
131     ierr = PetscFree(pc_gamg->m_data); CHKERRQ(ierr);
132   }
133   pc_gamg->m_data = 0; pc_gamg->m_data_sz = 0;
134   PetscFunctionReturn(0);
135 }
136 
137 /* -------------------------------------------------------------------------- */
138 /*
139    partitionLevel
140 
141    Input Parameter:
142    . a_Amat_fine - matrix on this fine (k) level
143    . a_ndata_rows - size of data to move (coarse grid)
144    . a_ndata_cols - size of data to move (coarse grid)
145    In/Output Parameter:
146    . a_P_inout - prolongation operator to the next level (k-1)
147    . a_coarse_data - data that need to be moved
148    . a_nactive_proc - number of active procs
149    Output Parameter:
150    . a_Amat_crs - coarse matrix that is created (k-1)
151 */
152 
153 #define TOP_GRID_LIM 2*s_min_eq_proc /* this will happen anyway */
154 
155 #undef __FUNCT__
156 #define __FUNCT__ "partitionLevel"
157 PetscErrorCode partitionLevel( Mat a_Amat_fine,
158                                PetscInt a_ndata_rows,
159                                PetscInt a_ndata_cols,
160 			       PetscInt a_cbs,
161                                Mat *a_P_inout,
162                                PetscReal **a_coarse_data,
163                                PetscMPIInt *a_nactive_proc,
164                                Mat *a_Amat_crs
165                                )
166 {
167   PetscErrorCode   ierr;
168   Mat              Cmat,Pnew,Pold=*a_P_inout;
169   IS               new_indices,isnum;
170   MPI_Comm         wcomm = ((PetscObject)a_Amat_fine)->comm;
171   PetscMPIInt      mype,npe,new_npe,nactive;
172   PetscInt         neq,NN,Istart,Iend,Istart0,Iend0,ncrs_new,ncrs0;
173 
174   PetscFunctionBegin;
175   ierr = MPI_Comm_rank( wcomm, &mype ); CHKERRQ(ierr);
176   ierr = MPI_Comm_size( wcomm, &npe );  CHKERRQ(ierr);
177   /* RAP */
178 #ifdef USE_R
179   /* make R wih brute force for now */
180   ierr = MatTranspose( Pold, Pnew );
181   ierr = MatDestroy( &Pold );  CHKERRQ(ierr);
182   ierr = MatRARt( a_Amat_fine, Pnew, MAT_INITIAL_MATRIX, 2.0, &Cmat ); CHKERRQ(ierr);
183   Pold = Pnew;
184 #else
185   ierr = MatPtAP( a_Amat_fine, Pold, MAT_INITIAL_MATRIX, 2.0, &Cmat ); CHKERRQ(ierr);
186 #endif
187   ierr = MatSetBlockSize( Cmat, a_cbs );      CHKERRQ(ierr);
188   ierr = MatGetOwnershipRange( Cmat, &Istart0, &Iend0 ); CHKERRQ(ierr);
189   ncrs0 = (Iend0-Istart0)/a_cbs; assert((Iend0-Istart0)%a_cbs == 0);
190 
191   if( s_avoid_repart) {
192     *a_Amat_crs = Cmat; /* output */
193   }
194   else {
195     /* Repartition Cmat_{k} and move colums of P^{k}_{k-1} and coordinates accordingly */
196     Mat              adj;
197     const PetscInt *idx,data_sz=a_ndata_rows*a_ndata_cols;
198     const PetscInt  stride0=ncrs0*a_ndata_rows;
199     PetscInt        is_sz,*isnewproc_idx,ii,jj,kk,strideNew,*tidx;
200     /* create sub communicator  */
201     MPI_Comm        cm;
202     MPI_Group       wg, g2;
203     PetscInt       *counts,inpe;
204     PetscMPIInt    *ranks;
205     IS              isscat;
206     PetscScalar    *array;
207     Vec             src_crd, dest_crd;
208     PetscReal      *data = *a_coarse_data;
209     VecScatter      vecscat;
210     IS  isnewproc;
211 
212     /* get number of PEs to make active, reduce */
213     ierr = MatGetSize( Cmat, &neq, &NN );  CHKERRQ(ierr);
214     new_npe = neq/s_min_eq_proc; /* hardwire min. number of eq/proc */
215     if( new_npe == 0 || neq < TOP_GRID_LIM ) new_npe = 1;
216     else if (new_npe >= *a_nactive_proc ) new_npe = *a_nactive_proc; /* no change, rare */
217 
218     ierr = PetscMalloc( npe*sizeof(PetscMPIInt), &ranks ); CHKERRQ(ierr);
219     ierr = PetscMalloc( npe*sizeof(PetscInt), &counts ); CHKERRQ(ierr);
220 
221     ierr = MPI_Allgather( &ncrs0, 1, MPIU_INT, counts, 1, MPIU_INT, wcomm ); CHKERRQ(ierr);
222     assert(counts[mype]==ncrs0);
223     /* count real active pes */
224     for( nactive = jj = 0 ; jj < npe ; jj++) {
225       if( counts[jj] != 0 ) {
226 	ranks[nactive++] = jj;
227         }
228     }
229 
230     if (nactive < new_npe) new_npe = nactive; /* this can happen with empty input procs */
231 
232 #ifdef VERBOSE
233     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);
234 #endif
235 
236     *a_nactive_proc = new_npe; /* output */
237 
238     ierr = MPI_Comm_group( wcomm, &wg ); CHKERRQ(ierr);
239     ierr = MPI_Group_incl( wg, nactive, ranks, &g2 ); CHKERRQ(ierr);
240     ierr = MPI_Comm_create( wcomm, g2, &cm ); CHKERRQ(ierr);
241 
242     ierr = MPI_Group_free( &wg );                            CHKERRQ(ierr);
243     ierr = MPI_Group_free( &g2 );                            CHKERRQ(ierr);
244 
245     /* MatPartitioningApply call MatConvert, which is collective */
246 #if defined PETSC_USE_LOG
247     ierr = PetscLogEventBegin(gamg_setup_events[SET12],0,0,0,0);CHKERRQ(ierr);
248 #endif
249     if( a_cbs == 1) {
250       ierr = MatConvert( Cmat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
251     }
252     else{
253       /* make a scalar matrix to partition */
254       Mat tMat;
255       PetscInt ncols,jj,Ii;
256       const PetscScalar *vals;
257       const PetscInt *idx;
258       PetscInt *d_nnz;
259       static int llev = 0;
260 
261       ierr = PetscMalloc( ncrs0*sizeof(PetscInt), &d_nnz ); CHKERRQ(ierr);
262       for ( Ii = Istart0, jj = 0 ; Ii < Iend0 ; Ii += a_cbs, jj++ ) {
263         ierr = MatGetRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
264         d_nnz[jj] = ncols/a_cbs;
265         if( d_nnz[jj] > ncrs0 ) d_nnz[jj] = ncrs0;
266         ierr = MatRestoreRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
267       }
268 
269       ierr = MatCreateMPIAIJ( wcomm, ncrs0, ncrs0,
270                               PETSC_DETERMINE, PETSC_DETERMINE,
271                               0, d_nnz, 0, d_nnz,
272                               &tMat );
273       CHKERRQ(ierr);
274       ierr = PetscFree( d_nnz ); CHKERRQ(ierr);
275 
276       for ( ii = Istart0; ii < Iend0; ii++ ) {
277         PetscInt dest_row = ii/a_cbs;
278         ierr = MatGetRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
279         for( jj = 0 ; jj < ncols ; jj++ ){
280           PetscInt dest_col = idx[jj]/a_cbs;
281           PetscScalar v = 1.0;
282           ierr = MatSetValues(tMat,1,&dest_row,1,&dest_col,&v,ADD_VALUES); CHKERRQ(ierr);
283         }
284         ierr = MatRestoreRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
285       }
286       ierr = MatAssemblyBegin(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
287       ierr = MatAssemblyEnd(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
288 
289       if( llev++ == -1 ) {
290 	PetscViewer viewer; char fname[32];
291 	sprintf(fname,"part_mat_%d.mat",llev);
292 	PetscViewerBinaryOpen(wcomm,fname,FILE_MODE_WRITE,&viewer);
293 	ierr = MatView( tMat, viewer ); CHKERRQ(ierr);
294 	ierr = PetscViewerDestroy( &viewer );
295       }
296 
297       ierr = MatConvert( tMat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
298 
299       ierr = MatDestroy( &tMat );  CHKERRQ(ierr);
300     }
301     if( ncrs0 != 0 ){
302       const PetscInt *is_idx;
303       MatPartitioning  mpart;
304       /* hack to fix global data that pmetis.c uses in 'adj' */
305       for( nactive = jj = 0 ; jj < npe ; jj++ ) {
306 	if( counts[jj] != 0 ) {
307 	  adj->rmap->range[nactive++] = adj->rmap->range[jj];
308 	}
309       }
310       adj->rmap->range[nactive] = adj->rmap->range[npe];
311 
312       ierr = MatPartitioningCreate( cm, &mpart ); CHKERRQ(ierr);
313       ierr = MatPartitioningSetAdjacency( mpart, adj ); CHKERRQ(ierr);
314       ierr = MatPartitioningSetFromOptions( mpart );    CHKERRQ(ierr);
315       ierr = MatPartitioningSetNParts( mpart, new_npe );CHKERRQ(ierr);
316       ierr = MatPartitioningApply( mpart, &isnewproc ); CHKERRQ(ierr);
317       ierr = MatPartitioningDestroy( &mpart );          CHKERRQ(ierr);
318 
319       /* collect IS info */
320       ierr = ISGetLocalSize( isnewproc, &is_sz );       CHKERRQ(ierr);
321       ierr = PetscMalloc( a_cbs*is_sz*sizeof(PetscInt), &isnewproc_idx ); CHKERRQ(ierr);
322       ierr = ISGetIndices( isnewproc, &is_idx );        CHKERRQ(ierr);
323       /* spread partitioning across machine - best way ??? */
324       NN = 1; /*npe/new_npe;*/
325       for( kk = jj = 0 ; kk < is_sz ; kk++ ){
326         for( ii = 0 ; ii < a_cbs ; ii++, jj++ ) {
327           isnewproc_idx[jj] = is_idx[kk] * NN; /* distribution */
328         }
329       }
330       ierr = ISRestoreIndices( isnewproc, &is_idx );     CHKERRQ(ierr);
331       ierr = ISDestroy( &isnewproc );                    CHKERRQ(ierr);
332       ierr = MPI_Comm_free( &cm );              CHKERRQ(ierr);
333 
334       is_sz *= a_cbs;
335     }
336     else{
337       isnewproc_idx = 0;
338       is_sz = 0;
339     }
340     ierr = MatDestroy( &adj );                       CHKERRQ(ierr);
341     ierr = ISCreateGeneral( wcomm, is_sz, isnewproc_idx, PETSC_COPY_VALUES, &isnewproc );
342     if( isnewproc_idx != 0 ) {
343       ierr = PetscFree( isnewproc_idx );  CHKERRQ(ierr);
344     }
345 
346     /*
347      Create an index set from the isnewproc index set to indicate the mapping TO
348      */
349     ierr = ISPartitioningToNumbering( isnewproc, &isnum ); CHKERRQ(ierr);
350     /*
351      Determine how many elements are assigned to each processor
352      */
353     inpe = npe;
354     ierr = ISPartitioningCount( isnewproc, inpe, counts ); CHKERRQ(ierr);
355     ierr = ISDestroy( &isnewproc );                       CHKERRQ(ierr);
356     ncrs_new = counts[mype]/a_cbs;
357     strideNew = ncrs_new*a_ndata_rows;
358 #if defined PETSC_USE_LOG
359     ierr = PetscLogEventEnd(gamg_setup_events[SET12],0,0,0,0);   CHKERRQ(ierr);
360 #endif
361     /* Create a vector to contain the newly ordered element information */
362     ierr = VecCreate( wcomm, &dest_crd );
363     ierr = VecSetSizes( dest_crd, data_sz*ncrs_new, PETSC_DECIDE ); CHKERRQ(ierr);
364     ierr = VecSetFromOptions( dest_crd ); CHKERRQ(ierr); /* this is needed! */
365     /*
366      There are 'a_ndata_rows*a_ndata_cols' data items per node, (one can think of the vectors of having
367      a block size of ...).  Note, ISs are expanded into equation space by 'a_cbs'.
368      */
369     ierr = PetscMalloc( (ncrs0*data_sz)*sizeof(PetscInt), &tidx ); CHKERRQ(ierr);
370     ierr = ISGetIndices( isnum, &idx ); CHKERRQ(ierr);
371     for(ii=0,jj=0; ii<ncrs0 ; ii++) {
372       PetscInt id = idx[ii*a_cbs]/a_cbs; /* get node back */
373       for( kk=0; kk<data_sz ; kk++, jj++) tidx[jj] = id*data_sz + kk;
374     }
375     ierr = ISRestoreIndices( isnum, &idx ); CHKERRQ(ierr);
376     ierr = ISCreateGeneral( wcomm, data_sz*ncrs0, tidx, PETSC_COPY_VALUES, &isscat );
377     CHKERRQ(ierr);
378     ierr = PetscFree( tidx );  CHKERRQ(ierr);
379     /*
380      Create a vector to contain the original vertex information for each element
381      */
382     ierr = VecCreateSeq( PETSC_COMM_SELF, data_sz*ncrs0, &src_crd ); CHKERRQ(ierr);
383     for( jj=0; jj<a_ndata_cols ; jj++ ) {
384       for( ii=0 ; ii<ncrs0 ; ii++) {
385 	for( kk=0; kk<a_ndata_rows ; kk++ ) {
386 	  PetscInt ix = ii*a_ndata_rows + kk + jj*stride0, jx = ii*data_sz + kk*a_ndata_cols + jj;
387           PetscScalar tt = (PetscScalar)data[ix];
388 	  ierr = VecSetValues( src_crd, 1, &jx, &tt, INSERT_VALUES );  CHKERRQ(ierr);
389 	}
390       }
391     }
392     ierr = VecAssemblyBegin(src_crd); CHKERRQ(ierr);
393     ierr = VecAssemblyEnd(src_crd); CHKERRQ(ierr);
394     /*
395       Scatter the element vertex information (still in the original vertex ordering)
396       to the correct processor
397     */
398     ierr = VecScatterCreate( src_crd, PETSC_NULL, dest_crd, isscat, &vecscat);
399     CHKERRQ(ierr);
400     ierr = ISDestroy( &isscat );       CHKERRQ(ierr);
401     ierr = VecScatterBegin(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
402     ierr = VecScatterEnd(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
403     ierr = VecScatterDestroy( &vecscat );       CHKERRQ(ierr);
404     ierr = VecDestroy( &src_crd );       CHKERRQ(ierr);
405     /*
406       Put the element vertex data into a new allocation of the gdata->ele
407     */
408     ierr = PetscFree( *a_coarse_data );    CHKERRQ(ierr);
409     ierr = PetscMalloc( data_sz*ncrs_new*sizeof(PetscReal), a_coarse_data );    CHKERRQ(ierr);
410 
411     ierr = VecGetArray( dest_crd, &array );    CHKERRQ(ierr);
412     data = *a_coarse_data;
413     for( jj=0; jj<a_ndata_cols ; jj++ ) {
414       for( ii=0 ; ii<ncrs_new ; ii++) {
415 	for( kk=0; kk<a_ndata_rows ; kk++ ) {
416 	  PetscInt ix = ii*a_ndata_rows + kk + jj*strideNew, jx = ii*data_sz + kk*a_ndata_cols + jj;
417 	  data[ix] = PetscRealPart(array[jx]);
418 	  array[jx] = 1.e300;
419 	}
420       }
421     }
422     ierr = VecRestoreArray( dest_crd, &array );    CHKERRQ(ierr);
423     ierr = VecDestroy( &dest_crd );    CHKERRQ(ierr);
424     /*
425       Invert for MatGetSubMatrix
426     */
427     ierr = ISInvertPermutation( isnum, ncrs_new*a_cbs, &new_indices ); CHKERRQ(ierr);
428     ierr = ISSort( new_indices ); CHKERRQ(ierr); /* is this needed? */
429     ierr = ISDestroy( &isnum ); CHKERRQ(ierr);
430     /* A_crs output */
431     ierr = MatGetSubMatrix( Cmat, new_indices, new_indices, MAT_INITIAL_MATRIX, a_Amat_crs );
432     CHKERRQ(ierr);
433 
434     ierr = MatDestroy( &Cmat ); CHKERRQ(ierr);
435     Cmat = *a_Amat_crs; /* output */
436     ierr = MatSetBlockSize( Cmat, a_cbs );      CHKERRQ(ierr);
437 
438     /* prolongator */
439     ierr = MatGetOwnershipRange( Pold, &Istart, &Iend );    CHKERRQ(ierr);
440     {
441       IS findices;
442       ierr = ISCreateStride(wcomm,Iend-Istart,Istart,1,&findices);   CHKERRQ(ierr);
443 #ifdef USE_R
444       ierr = MatGetSubMatrix( Pold, new_indices, findices, MAT_INITIAL_MATRIX, &Pnew );
445 #else
446       ierr = MatGetSubMatrix( Pold, findices, new_indices, MAT_INITIAL_MATRIX, &Pnew );
447 #endif
448       CHKERRQ(ierr);
449 
450       ierr = ISDestroy( &findices ); CHKERRQ(ierr);
451     }
452 
453     ierr = MatDestroy( a_P_inout ); CHKERRQ(ierr);
454     *a_P_inout = Pnew; /* output */
455 
456     ierr = ISDestroy( &new_indices ); CHKERRQ(ierr);
457     ierr = PetscFree( counts );  CHKERRQ(ierr);
458     ierr = PetscFree( ranks );  CHKERRQ(ierr);
459   }
460 
461   PetscFunctionReturn(0);
462 }
463 
464 /* -------------------------------------------------------------------------- */
465 /*
466    PCSetUp_GAMG - Prepares for the use of the GAMG preconditioner
467                     by setting data structures and options.
468 
469    Input Parameter:
470 .  pc - the preconditioner context
471 
472    Application Interface Routine: PCSetUp()
473 
474    Notes:
475    The interface routine PCSetUp() is not usually called directly by
476    the user, but instead is called by PCApply() if necessary.
477 */
478 #undef __FUNCT__
479 #define __FUNCT__ "PCSetUp_GAMG"
480 PetscErrorCode PCSetUp_GAMG( PC a_pc )
481 {
482   PetscErrorCode  ierr;
483   PC_MG           *mg = (PC_MG*)a_pc->data;
484   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
485   PC_MG_Levels   **mglevels = mg->levels;
486   Mat              Amat = a_pc->mat, Pmat = a_pc->pmat;
487   PetscInt         fine_level, level, level1, M, N, bs, nloc, lidx, Istart, Iend;
488   MPI_Comm         wcomm = ((PetscObject)a_pc)->comm;
489   PetscMPIInt      mype,npe,nactivepe;
490   PetscBool        isOK;
491   Mat              Aarr[GAMG_MAXLEVELS], Parr[GAMG_MAXLEVELS];
492   PetscReal       *coarse_data = 0, *data, emaxs[GAMG_MAXLEVELS];
493   MatInfo          info;
494 
495   PetscFunctionBegin;
496   pc_gamg->m_count++;
497   if( a_pc->setupcalled > 0 ) {
498     /* just do Galerkin grids */
499     Mat B,dA,dB;
500 
501     /* PCSetUp_MG seems to insists on setting this to GMRES */
502     ierr = KSPSetType( mglevels[0]->smoothd, KSPPREONLY ); CHKERRQ(ierr);
503 
504     /* currently only handle case where mat and pmat are the same on coarser levels */
505     ierr = KSPGetOperators(mglevels[pc_gamg->m_Nlevels-1]->smoothd,&dA,&dB,PETSC_NULL);CHKERRQ(ierr);
506     /* (re)set to get dirty flag */
507     ierr = KSPSetOperators(mglevels[pc_gamg->m_Nlevels-1]->smoothd,dA,dB,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
508     ierr = KSPSetUp( mglevels[pc_gamg->m_Nlevels-1]->smoothd ); CHKERRQ(ierr);
509 
510     for (level=pc_gamg->m_Nlevels-2; level>-1; level--) {
511       ierr = KSPGetOperators(mglevels[level]->smoothd,PETSC_NULL,&B,PETSC_NULL);CHKERRQ(ierr);
512       /* the first time through the matrix structure has changed from repartitioning */
513       if( pc_gamg->m_count == 2 ) {
514         ierr = MatDestroy( &B );  CHKERRQ(ierr);
515         ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_INITIAL_MATRIX,1.0,&B);CHKERRQ(ierr);
516         mglevels[level]->A = B;
517       }
518       else {
519         ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_REUSE_MATRIX,1.0,&B);CHKERRQ(ierr);
520       }
521       ierr = KSPSetOperators(mglevels[level]->smoothd,B,B,SAME_NONZERO_PATTERN); CHKERRQ(ierr);
522       dB = B;
523       /* setup KSP/PC */
524       ierr = KSPSetUp( mglevels[level]->smoothd ); CHKERRQ(ierr);
525     }
526 
527 #define PRINT_MATS !PETSC_TRUE
528     /* plot levels - A */
529     if( PRINT_MATS ) {
530       for (lidx=0, level=pc_gamg->m_Nlevels-1; level>0 ; level--,lidx++){
531         PetscViewer viewer;
532         char fname[32]; KSP smoother; Mat Tmat, TTm;
533         ierr = PCMGGetSmoother( a_pc, lidx, &smoother ); CHKERRQ(ierr);
534         ierr = KSPGetOperators( smoother, &Tmat, &TTm, 0 ); CHKERRQ(ierr);
535         sprintf(fname,"Amat_%d_%d.m",(int)pc_gamg->m_count,(int)level);
536         ierr = PetscViewerASCIIOpen( wcomm, fname, &viewer );  CHKERRQ(ierr);
537         ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
538         ierr = MatView( Tmat, viewer ); CHKERRQ(ierr);
539         ierr = PetscViewerDestroy( &viewer );
540       }
541     }
542 
543     a_pc->setupcalled = 2;
544 
545     PetscFunctionReturn(0);
546   }
547   ierr = MPI_Comm_rank(wcomm,&mype);CHKERRQ(ierr);
548   ierr = MPI_Comm_size(wcomm,&npe);CHKERRQ(ierr);
549   /* GAMG requires input of fine-grid matrix. It determines nlevels. */
550   ierr = MatGetBlockSize( Amat, &bs ); CHKERRQ(ierr);
551   ierr = MatGetSize( Amat, &M, &N );CHKERRQ(ierr);
552   ierr = MatGetOwnershipRange( Amat, &Istart, &Iend ); CHKERRQ(ierr);
553   nloc = (Iend-Istart)/bs; assert((Iend-Istart)%bs == 0);
554 
555   /* get data of not around */
556   if( pc_gamg->m_data == 0 && nloc > 0 ) {
557     ierr  = PCSetCoordinates_GAMG( a_pc, -1, 0 );    CHKERRQ( ierr );
558   }
559   data = pc_gamg->m_data;
560 
561   /* Get A_i and R_i */
562   ierr = MatGetInfo(Amat,MAT_GLOBAL_SUM,&info); CHKERRQ(ierr);
563 #ifdef VERBOSE
564   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",
565 	      mype,__FUNCT__,0,N,pc_gamg->m_data_rows,pc_gamg->m_data_cols,
566 	      (int)(info.nz_used/(PetscReal)N),npe);
567 #endif
568   for ( level=0, Aarr[0] = Pmat, nactivepe = npe; /* hard wired stopping logic */
569         level < (GAMG_MAXLEVELS-1) && (level==0 || M>TOP_GRID_LIM); /* && (npe==1 || nactivepe>1); */
570         level++ ){
571     level1 = level + 1;
572 #if (defined PETSC_USE_LOG && defined GAMG_STAGES)
573     ierr = PetscLogStagePush(gamg_stages[level]); CHKERRQ( ierr );
574 #endif
575 #if defined PETSC_USE_LOG
576     ierr = PetscLogEventBegin(gamg_setup_events[SET1],0,0,0,0);CHKERRQ(ierr);
577 #endif
578     ierr = createProlongation(Aarr[level], data, pc_gamg->m_dim, pc_gamg->m_data_cols, pc_gamg->m_method,
579                               level, s_threshold, &bs, &Parr[level1], &coarse_data, &isOK, &emaxs[level] );
580     CHKERRQ(ierr);
581     ierr = PetscFree( data ); CHKERRQ( ierr );
582 #if defined PETSC_USE_LOG
583     ierr = PetscLogEventEnd(gamg_setup_events[SET1],0,0,0,0);CHKERRQ(ierr);
584 #endif
585     if(level==0) Aarr[0] = Amat; /* use Pmat for finest level setup, but use mat for solver */
586     if( isOK ) {
587 #if defined PETSC_USE_LOG
588       ierr = PetscLogEventBegin(gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
589 #endif
590       ierr = partitionLevel( Aarr[level], (pc_gamg->m_method != 0) ? bs : 1, pc_gamg->m_data_cols, bs,
591                              &Parr[level1], &coarse_data, &nactivepe, &Aarr[level1] );
592       CHKERRQ(ierr);
593 #if defined PETSC_USE_LOG
594       ierr = PetscLogEventEnd(gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
595 #endif
596       ierr = MatGetSize( Aarr[level1], &M, &N );CHKERRQ(ierr);
597       ierr = MatGetInfo(Aarr[level1],MAT_GLOBAL_SUM,&info); CHKERRQ(ierr);
598 #ifdef VERBOSE
599       PetscPrintf(PETSC_COMM_WORLD,"\t\t[%d]%s %d) N=%d, n data cols=%d, nnz/row (ave)=%d, %d active pes\n",
600 		  mype,__FUNCT__,(int)level1,N,pc_gamg->m_data_cols,
601 		  (int)(info.nz_used/(PetscReal)N),nactivepe);
602 #endif
603       /* coarse grids with SA can have zero row/cols from singleton aggregates */
604       /* aggregation method should gaurrentee this does not happen! */
605 
606 #ifdef VERBOSE
607       if( PETSC_TRUE ){
608         Vec diag; PetscScalar *data_arr,v; PetscInt Istart,Iend,kk,nloceq,id;
609         v = 1.e-10; /* LU factor has hard wired numbers for small diags so this needs to match (yuk) */
610         ierr = MatGetOwnershipRange(Aarr[level1], &Istart, &Iend); CHKERRQ(ierr);
611         nloceq = Iend-Istart;
612         ierr = MatGetVecs( Aarr[level1], &diag, 0 );    CHKERRQ(ierr);
613         ierr = MatGetDiagonal( Aarr[level1], diag );    CHKERRQ(ierr);
614         ierr = VecGetArray( diag, &data_arr );   CHKERRQ(ierr);
615         for(kk=0;kk<nloceq;kk++){
616           if(data_arr[kk]==0.0) {
617             id = kk + Istart;
618             ierr = MatSetValues(Aarr[level1],1,&id,1,&id,&v,INSERT_VALUES);
619             CHKERRQ(ierr);
620             PetscPrintf(PETSC_COMM_SELF,"\t[%d]%s warning: added zero to diag (%d) on level %d \n",mype,__FUNCT__,id,level1);
621           }
622         }
623         ierr = VecRestoreArray( diag, &data_arr ); CHKERRQ(ierr);
624         ierr = VecDestroy( &diag );                CHKERRQ(ierr);
625         ierr = MatAssemblyBegin(Aarr[level1],MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
626         ierr = MatAssemblyEnd(Aarr[level1],MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
627       }
628 #endif
629     }
630     else{
631       coarse_data = 0;
632       break;
633     }
634     data = coarse_data;
635 
636 #if (defined PETSC_USE_LOG && defined GAMG_STAGES)
637     ierr = PetscLogStagePop(); CHKERRQ( ierr );
638 #endif
639   }
640   if( coarse_data ) {
641     ierr = PetscFree( coarse_data ); CHKERRQ( ierr );
642   }
643 #ifdef VERBOSE
644   PetscPrintf(PETSC_COMM_WORLD,"\t[%d]%s %d levels\n",0,__FUNCT__,level + 1);
645 #endif
646   pc_gamg->m_data = 0; /* destroyed coordinate data */
647   pc_gamg->m_Nlevels = level + 1;
648   fine_level = level;
649   ierr = PCMGSetLevels(a_pc,pc_gamg->m_Nlevels,PETSC_NULL);CHKERRQ(ierr);
650 
651   /* set default smoothers */
652   for ( lidx=1, level = pc_gamg->m_Nlevels-2;
653         lidx <= fine_level;
654         lidx++, level--) {
655     PetscReal emax, emin;
656     KSP smoother; PC subpc;
657     ierr = PCMGGetSmoother( a_pc, lidx, &smoother ); CHKERRQ(ierr);
658     ierr = KSPSetType( smoother, KSPCHEBYCHEV );CHKERRQ(ierr);
659     if( emaxs[level] > 0.0 ) emax=emaxs[level];
660     else{ /* eigen estimate 'emax' */
661       KSP eksp; Mat Lmat = Aarr[level];
662       Vec bb, xx; PC pc;
663 
664       ierr = MatGetVecs( Lmat, &bb, 0 );         CHKERRQ(ierr);
665       ierr = MatGetVecs( Lmat, &xx, 0 );         CHKERRQ(ierr);
666       {
667 	PetscRandom    rctx;
668 	ierr = PetscRandomCreate(wcomm,&rctx);CHKERRQ(ierr);
669 	ierr = PetscRandomSetFromOptions(rctx);CHKERRQ(ierr);
670 	ierr = VecSetRandom(bb,rctx);CHKERRQ(ierr);
671 	ierr = PetscRandomDestroy( &rctx ); CHKERRQ(ierr);
672       }
673       ierr = KSPCreate(wcomm,&eksp);CHKERRQ(ierr);
674       ierr = KSPSetType( eksp, KSPCG );                      CHKERRQ(ierr);
675       ierr = KSPSetInitialGuessNonzero( eksp, PETSC_FALSE ); CHKERRQ(ierr);
676       ierr = KSPSetOperators( eksp, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ( ierr );
677       ierr = KSPGetPC( eksp, &pc );CHKERRQ( ierr );
678       ierr = PCSetType( pc, PETSC_GAMG_SMOOTHER ); CHKERRQ(ierr); /* should be same as eigen estimates op. */
679       ierr = KSPSetTolerances( eksp, PETSC_DEFAULT, PETSC_DEFAULT, PETSC_DEFAULT, 10 );
680       CHKERRQ(ierr);
681       ierr = KSPSetNormType( eksp, KSP_NORM_NONE );                 CHKERRQ(ierr);
682 
683       ierr = KSPSetComputeSingularValues( eksp,PETSC_TRUE ); CHKERRQ(ierr);
684       ierr = KSPSolve( eksp, bb, xx ); CHKERRQ(ierr);
685       ierr = KSPComputeExtremeSingularValues( eksp, &emax, &emin ); CHKERRQ(ierr);
686       ierr = VecDestroy( &xx );       CHKERRQ(ierr);
687       ierr = VecDestroy( &bb );       CHKERRQ(ierr);
688       ierr = KSPDestroy( &eksp );       CHKERRQ(ierr);
689 #ifdef VERBOSE
690       PetscPrintf(PETSC_COMM_WORLD,"\t\t\t%s PC setup max eigen=%e min=%e PC=%s\n",__FUNCT__,emax,emin,PETSC_GAMG_SMOOTHER);
691 #endif
692     }
693     {
694       PetscInt N1, N0, tt;
695       ierr = MatGetSize( Aarr[level], &N1, &tt );         CHKERRQ(ierr);
696       ierr = MatGetSize( Aarr[level+1], &N0, &tt );       CHKERRQ(ierr);
697       emin = 1.*emax/((PetscReal)N1/(PetscReal)N0); /* this should be about the coarsening rate */
698       emax *= 1.05;
699     }
700 
701     ierr = KSPSetOperators( smoother, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN );
702     ierr = KSPChebychevSetEigenvalues( smoother, emax, emin );CHKERRQ(ierr);
703     /* ierr = KSPSetTolerances(smoother,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT,2); CHKERRQ(ierr); */
704     ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
705     ierr = PCSetType( subpc, PETSC_GAMG_SMOOTHER ); CHKERRQ(ierr);
706     ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
707   }
708   {
709     /* coarse grid */
710     KSP smoother,*k2; PC subpc,pc2; PetscInt ii,first;
711     Mat Lmat = Aarr[pc_gamg->m_Nlevels-1];
712     ierr = PCMGGetSmoother( a_pc, 0, &smoother ); CHKERRQ(ierr);
713     ierr = KSPSetOperators( smoother, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ(ierr);
714     ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
715     ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
716     ierr = PCSetType( subpc, PCBJACOBI ); CHKERRQ(ierr);
717     ierr = PCSetUp( subpc ); CHKERRQ(ierr);
718     ierr = PCBJacobiGetSubKSP(subpc,&ii,&first,&k2);CHKERRQ(ierr);
719     assert(ii==1);
720     ierr = KSPGetPC(k2[0],&pc2);CHKERRQ(ierr);
721     ierr = PCSetType( pc2, PCLU ); CHKERRQ(ierr);
722   }
723 
724   /* should be called in PCSetFromOptions_GAMG(), but cannot be called prior to PCMGSetLevels() */
725   ierr = PCSetFromOptions_MG(a_pc); CHKERRQ(ierr);
726   {
727     PetscBool galerkin;
728     ierr = PCMGGetGalerkin( a_pc,  &galerkin); CHKERRQ(ierr);
729     if(galerkin){
730       SETERRQ(wcomm,PETSC_ERR_ARG_WRONG, "GAMG does galerkin manually so it must not be used in PC_MG.");
731     }
732   }
733 
734   /* plot levels - R/P */
735   if( PRINT_MATS ) {
736     for (level=pc_gamg->m_Nlevels-1;level>0;level--){
737       PetscViewer viewer;
738       char fname[32];
739       sprintf(fname,"Pmat_%d_%d.m",(int)pc_gamg->m_count,(int)level);
740       ierr = PetscViewerASCIIOpen( wcomm, fname, &viewer );  CHKERRQ(ierr);
741       ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
742       ierr = MatView( Parr[level], viewer ); CHKERRQ(ierr);
743       ierr = PetscViewerDestroy( &viewer );
744       sprintf(fname,"Amat_%d_%d.m",(int)pc_gamg->m_count,(int)level);
745       ierr = PetscViewerASCIIOpen( wcomm, fname, &viewer );  CHKERRQ(ierr);
746       ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
747       ierr = MatView( Aarr[level], viewer ); CHKERRQ(ierr);
748       ierr = PetscViewerDestroy( &viewer );
749     }
750   }
751 
752   /* set interpolation between the levels, clean up */
753   for (lidx=0,level=pc_gamg->m_Nlevels-1;
754        lidx<fine_level;
755        lidx++, level--){
756     ierr = PCMGSetInterpolation( a_pc, lidx+1, Parr[level] );CHKERRQ(ierr);
757     ierr = MatDestroy( &Parr[level] );  CHKERRQ(ierr);
758     ierr = MatDestroy( &Aarr[level] );  CHKERRQ(ierr);
759   }
760 
761   /* setupcalled is set to 0 so that MG is setup from scratch */
762   a_pc->setupcalled = 0;
763   ierr = PCSetUp_MG( a_pc );CHKERRQ( ierr );
764   a_pc->setupcalled = 1; /* use 1 as signal that this has not been re-setup */
765 
766   {
767     KSP smoother;  /* PCSetUp_MG seems to insists on setting this to GMRES on coarse grid */
768     ierr = PCMGGetSmoother( a_pc, 0, &smoother ); CHKERRQ(ierr);
769     ierr = KSPSetType( smoother, KSPPREONLY ); CHKERRQ(ierr);
770     ierr = KSPSetUp( smoother ); CHKERRQ(ierr);
771   }
772 
773   PetscFunctionReturn(0);
774 }
775 
776 /* ------------------------------------------------------------------------- */
777 /*
778    PCDestroy_GAMG - Destroys the private context for the GAMG preconditioner
779    that was created with PCCreate_GAMG().
780 
781    Input Parameter:
782 .  pc - the preconditioner context
783 
784    Application Interface Routine: PCDestroy()
785 */
786 #undef __FUNCT__
787 #define __FUNCT__ "PCDestroy_GAMG"
788 PetscErrorCode PCDestroy_GAMG(PC pc)
789 {
790   PetscErrorCode  ierr;
791   PC_MG           *mg = (PC_MG*)pc->data;
792   PC_GAMG         *pc_gamg= (PC_GAMG*)mg->innerctx;
793 
794   PetscFunctionBegin;
795   ierr = PCReset_GAMG(pc);CHKERRQ(ierr);
796   ierr = PetscFree(pc_gamg);CHKERRQ(ierr);
797   ierr = PCDestroy_MG(pc);CHKERRQ(ierr);
798   PetscFunctionReturn(0);
799 }
800 
801 
802 #undef __FUNCT__
803 #define __FUNCT__ "PCGAMGSetProcEqLim"
804 /*@
805    PCGAMGSetProcEqLim - Set number of equations to aim for on coarse grids via
806    processor reduction.
807 
808    Not Collective on PC
809 
810    Input Parameters:
811 .  pc - the preconditioner context
812 
813 
814    Options Database Key:
815 .  -pc_gamg_process_eq_limit
816 
817    Level: intermediate
818 
819    Concepts: Unstructured multrigrid preconditioner
820 
821 .seealso: ()
822 @*/
823 PetscErrorCode  PCGAMGSetProcEqLim(PC pc, PetscInt n)
824 {
825   PetscErrorCode ierr;
826 
827   PetscFunctionBegin;
828   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
829   ierr = PetscTryMethod(pc,"PCGAMGSetProcEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
830   PetscFunctionReturn(0);
831 }
832 
833 EXTERN_C_BEGIN
834 #undef __FUNCT__
835 #define __FUNCT__ "PCGAMGSetProcEqLim_GAMG"
836 PetscErrorCode PCGAMGSetProcEqLim_GAMG(PC pc, PetscInt n)
837 {
838   /* PC_MG           *mg = (PC_MG*)pc->data; */
839   /* PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx; */
840 
841   PetscFunctionBegin;
842   if(n>0) s_min_eq_proc = n;
843   PetscFunctionReturn(0);
844 }
845 EXTERN_C_END
846 
847 #undef __FUNCT__
848 #define __FUNCT__ "PCGAMGAvoidRepartitioning"
849 /*@
850    PCGAMGAvoidRepartitioning - Do not repartition the coarse grids
851 
852    Collective on PC
853 
854    Input Parameters:
855 .  pc - the preconditioner context
856 
857 
858    Options Database Key:
859 .  -pc_gamg_avoid_repartitioning
860 
861    Level: intermediate
862 
863    Concepts: Unstructured multrigrid preconditioner
864 
865 .seealso: ()
866 @*/
867 PetscErrorCode PCGAMGAvoidRepartitioning(PC pc, PetscBool n)
868 {
869   PetscErrorCode ierr;
870 
871   PetscFunctionBegin;
872   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
873   ierr = PetscTryMethod(pc,"PCGAMGAvoidRepartitioning_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
874   PetscFunctionReturn(0);
875 }
876 
877 EXTERN_C_BEGIN
878 #undef __FUNCT__
879 #define __FUNCT__ "PCGAMGAvoidRepartitioning_GAMG"
880 PetscErrorCode PCGAMGAvoidRepartitioning_GAMG(PC pc, PetscBool n)
881 {
882   /* PC_MG           *mg = (PC_MG*)pc->data; */
883   /* PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx; */
884 
885   PetscFunctionBegin;
886   s_avoid_repart = n;
887   PetscFunctionReturn(0);
888 }
889 EXTERN_C_END
890 
891 #undef __FUNCT__
892 #define __FUNCT__ "PCGAMGSetThreshold"
893 /*@
894    PCGAMGSetThreshold - Relative threshold to use for dropping edges in aggregation graph
895 
896    Not collective on PC
897 
898    Input Parameters:
899 .  pc - the preconditioner context
900 
901 
902    Options Database Key:
903 .  -pc_gamg_threshold
904 
905    Level: intermediate
906 
907    Concepts: Unstructured multrigrid preconditioner
908 
909 .seealso: ()
910 @*/
911 PetscErrorCode PCGAMGSetThreshold(PC pc, PetscReal n)
912 {
913   PetscErrorCode ierr;
914 
915   PetscFunctionBegin;
916   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
917   ierr = PetscTryMethod(pc,"PCGAMGSetThreshold_C",(PC,PetscReal),(pc,n));CHKERRQ(ierr);
918   PetscFunctionReturn(0);
919 }
920 
921 EXTERN_C_BEGIN
922 #undef __FUNCT__
923 #define __FUNCT__ "PCGAMGSetThreshold_GAMG"
924 PetscErrorCode PCGAMGSetThreshold_GAMG(PC pc, PetscReal n)
925 {
926   /* PC_MG           *mg = (PC_MG*)pc->data; */
927   /* PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx; */
928 
929   PetscFunctionBegin;
930   s_threshold = n;
931   PetscFunctionReturn(0);
932 }
933 EXTERN_C_END
934 
935 #undef __FUNCT__
936 #define __FUNCT__ "PCGAMGSetSolverType"
937 /*@
938    PCGAMGSetSolverType - Set solution method.
939 
940    Collective on PC
941 
942    Input Parameters:
943 .  pc - the preconditioner context
944 
945 
946    Options Database Key:
947 .  -pc_gamg_type
948 
949    Level: intermediate
950 
951    Concepts: Unstructured multrigrid preconditioner
952 
953 .seealso: ()
954 @*/
955 PetscErrorCode PCGAMGSetSolverType(PC pc, char str[], PetscInt sz )
956 {
957   PetscErrorCode ierr;
958 
959   PetscFunctionBegin;
960   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
961   ierr = PetscTryMethod(pc,"PCGAMGSetSolverType_C",(PC,char[],PetscInt),(pc,str,sz));
962   CHKERRQ(ierr);
963   PetscFunctionReturn(0);
964 }
965 
966 EXTERN_C_BEGIN
967 #undef __FUNCT__
968 #define __FUNCT__ "PCGAMGSetSolverType_GAMG"
969 PetscErrorCode PCGAMGSetSolverType_GAMG(PC pc, char str[], PetscInt sz )
970 {
971   PC_MG           *mg = (PC_MG*)pc->data;
972   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
973 
974   PetscFunctionBegin;
975   if(sz < 64) strcpy(pc_gamg->m_type,str);
976   PetscFunctionReturn(0);
977 }
978 EXTERN_C_END
979 
980 #undef __FUNCT__
981 #define __FUNCT__ "PCSetFromOptions_GAMG"
982 PetscErrorCode PCSetFromOptions_GAMG(PC pc)
983 {
984   PetscErrorCode  ierr;
985   PC_MG           *mg = (PC_MG*)pc->data;
986   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
987   PetscBool flag;
988 
989   PetscFunctionBegin;
990   ierr = PetscOptionsHead("GAMG options"); CHKERRQ(ierr);
991   {
992     ierr = PetscOptionsString("-pc_gamg_type",
993                               "Solver type: plane aggregation ('pa'), smoothed aggregation ('sa') or geometric multigrid (default)",
994                               "PCGAMGSetSolverType",
995                               pc_gamg->m_type,
996                               pc_gamg->m_type,
997                               64,
998                               &flag );
999     CHKERRQ(ierr);
1000     if( flag && pc_gamg->m_data != 0 ) {
1001       if( (strcmp(pc_gamg->m_type,"sa")==0 && pc_gamg->m_method != 2) ||
1002           (strcmp(pc_gamg->m_type,"pa")==0 && pc_gamg->m_method != 1) ||
1003           (strcmp(pc_gamg->m_type,"geo")==0 && pc_gamg->m_method != 0) ) {
1004         SETERRQ(((PetscObject)pc)->comm,PETSC_ERR_ARG_WRONG, "PCSetFromOptions called of PCSetCoordinates (with new method, after data was created)");
1005       }
1006     }
1007 
1008     if (flag && strcmp(pc_gamg->m_type,"sa") == 0) pc_gamg->m_method = 2;
1009     else if (flag && strcmp(pc_gamg->m_type,"pa") == 0) pc_gamg->m_method = 1;
1010     else pc_gamg->m_method = 0;
1011 
1012     /* common (static) variable */
1013     ierr = PetscOptionsBool("-pc_gamg_avoid_repartitioning",
1014                             "Do not repartion coarse grids (false)",
1015                             "PCGAMGAvoidRepartitioning",
1016                             s_avoid_repart,
1017                             &s_avoid_repart,
1018                             &flag);
1019     CHKERRQ(ierr);
1020 
1021     /* common (static) variable */
1022     ierr = PetscOptionsInt("-pc_gamg_process_eq_limit",
1023                            "Limit (goal) on number of equations per process on coarse grids",
1024                            "PCGAMGSetProcEqLim",
1025                            s_min_eq_proc,
1026                            &s_min_eq_proc,
1027                            &flag );
1028     CHKERRQ(ierr);
1029 
1030     /* common (static) variable */
1031     ierr = PetscOptionsReal("-pc_gamg_threshold",
1032                             "Relative threshold to use for dropping edges in aggregation graph",
1033                             "PCGAMGSetThreshold",
1034                             s_threshold,
1035                             &s_threshold,
1036                             &flag );
1037     CHKERRQ(ierr);
1038   }
1039   ierr = PetscOptionsTail();CHKERRQ(ierr);
1040 
1041   PetscFunctionReturn(0);
1042 }
1043 
1044 /* -------------------------------------------------------------------------- */
1045 /*
1046  PCCreate_GAMG - Creates a GAMG preconditioner context, PC_GAMG
1047 
1048    Input Parameter:
1049 .  pc - the preconditioner context
1050 
1051    Application Interface Routine: PCCreate()
1052 
1053   */
1054  /* MC
1055      PCGAMG - Use algebraic multigrid preconditioning. This preconditioner requires you provide
1056        fine grid discretization matrix and coordinates on the fine grid.
1057 
1058    Options Database Key:
1059    Multigrid options(inherited)
1060 +  -pc_mg_cycles <1>: 1 for V cycle, 2 for W-cycle (MGSetCycles)
1061 .  -pc_mg_smoothup <1>: Number of post-smoothing steps (MGSetNumberSmoothUp)
1062 .  -pc_mg_smoothdown <1>: Number of pre-smoothing steps (MGSetNumberSmoothDown)
1063    -pc_mg_type <multiplicative>: (one of) additive multiplicative full cascade kascade
1064    GAMG options:
1065 
1066    Level: intermediate
1067   Concepts: multigrid
1068 
1069 .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC, PCMGType,
1070            PCMGSetLevels(), PCMGGetLevels(), PCMGSetType(), MPSetCycles(), PCMGSetNumberSmoothDown(),
1071            PCMGSetNumberSmoothUp(), PCMGGetCoarseSolve(), PCMGSetResidual(), PCMGSetInterpolation(),
1072            PCMGSetRestriction(), PCMGGetSmoother(), PCMGGetSmootherUp(), PCMGGetSmootherDown(),
1073            PCMGSetCyclesOnLevel(), PCMGSetRhs(), PCMGSetX(), PCMGSetR()
1074 M */
1075 
1076 EXTERN_C_BEGIN
1077 #undef __FUNCT__
1078 #define __FUNCT__ "PCCreate_GAMG"
1079 PetscErrorCode  PCCreate_GAMG(PC pc)
1080 {
1081   PetscErrorCode  ierr;
1082   PC_GAMG         *pc_gamg;
1083   PC_MG           *mg;
1084   PetscClassId     cookie;
1085 #if defined PETSC_USE_LOG
1086   static int count = 0;
1087 #endif
1088 
1089   PetscFunctionBegin;
1090   /* PCGAMG is an inherited class of PCMG. Initialize pc as PCMG */
1091   ierr = PCSetType(pc,PCMG);CHKERRQ(ierr); /* calls PCCreate_MG() and MGCreate_Private() */
1092   ierr = PetscObjectChangeTypeName((PetscObject)pc,PCGAMG);CHKERRQ(ierr);
1093 
1094   /* create a supporting struct and attach it to pc */
1095   ierr = PetscNewLog(pc,PC_GAMG,&pc_gamg);CHKERRQ(ierr);
1096   pc_gamg->m_data_sz = 0; pc_gamg->m_data = 0; pc_gamg->m_count = 0;
1097   mg = (PC_MG*)pc->data;
1098   mg->innerctx = pc_gamg;
1099 
1100   pc_gamg->m_Nlevels    = -1;
1101 
1102   /* overwrite the pointers of PCMG by the functions of PCGAMG */
1103   pc->ops->setfromoptions = PCSetFromOptions_GAMG;
1104   pc->ops->setup          = PCSetUp_GAMG;
1105   pc->ops->reset          = PCReset_GAMG;
1106   pc->ops->destroy        = PCDestroy_GAMG;
1107 
1108   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1109 					    "PCSetCoordinates_C",
1110 					    "PCSetCoordinates_GAMG",
1111 					    PCSetCoordinates_GAMG);
1112   CHKERRQ(ierr);
1113 
1114   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1115 					    "PCGAMGSetProcEqLim_C",
1116 					    "PCGAMGSetProcEqLim_GAMG",
1117 					    PCGAMGSetProcEqLim_GAMG);
1118   CHKERRQ(ierr);
1119 
1120   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1121 					    "PCGAMGAvoidRepartitioning_C",
1122 					    "PCGAMGAvoidRepartitioning_GAMG",
1123 					    PCGAMGAvoidRepartitioning_GAMG);
1124   CHKERRQ(ierr);
1125 
1126   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1127 					    "PCGAMGSetThreshold_C",
1128 					    "PCGAMGSetThreshold_GAMG",
1129 					    PCGAMGSetThreshold_GAMG);
1130   CHKERRQ(ierr);
1131 
1132   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1133 					    "PCGAMGSetSolverType_C",
1134 					    "PCGAMGSetSolverType_GAMG",
1135 					    PCGAMGSetSolverType_GAMG);
1136   CHKERRQ(ierr);
1137 
1138 #if defined PETSC_USE_LOG
1139   if( count++ == 0 ) {
1140     PetscClassIdRegister("GAMG Setup",&cookie);
1141     PetscLogEventRegister("GAMG: createProl", cookie, &gamg_setup_events[SET1]);
1142     PetscLogEventRegister("  Graph", cookie, &gamg_setup_events[GRAPH]);
1143     PetscLogEventRegister("    G.Mat", cookie, &gamg_setup_events[GRAPH_MAT]);
1144     PetscLogEventRegister("    G.Filter", cookie, &gamg_setup_events[GRAPH_FILTER]);
1145     PetscLogEventRegister("    G.Square", cookie, &gamg_setup_events[GRAPH_SQR]);
1146     PetscLogEventRegister("  MIS/Agg", cookie, &gamg_setup_events[SET4]);
1147     PetscLogEventRegister("  geo: growSupp", cookie, &gamg_setup_events[SET5]);
1148     PetscLogEventRegister("  geo: triangle", cookie, &gamg_setup_events[SET6]);
1149     PetscLogEventRegister("    search&set", cookie, &gamg_setup_events[FIND_V]);
1150     PetscLogEventRegister("  SA: init", cookie, &gamg_setup_events[SET7]);
1151     /* PetscLogEventRegister("  SA: frmProl0", cookie, &gamg_setup_events[SET8]); */
1152     PetscLogEventRegister("  SA: smooth", cookie, &gamg_setup_events[SET9]);
1153     PetscLogEventRegister("GAMG: partLevel", cookie, &gamg_setup_events[SET2]);
1154     PetscLogEventRegister("  PL repartition", cookie, &gamg_setup_events[SET12]);
1155     /* PetscLogEventRegister(" PL move data", cookie, &gamg_setup_events[SET13]); */
1156     /* PetscLogEventRegister("GAMG: fix", cookie, &gamg_setup_events[SET10]); */
1157     /* PetscLogEventRegister("GAMG: set levels", cookie, &gamg_setup_events[SET11]); */
1158 
1159     /* create timer stages */
1160 #if defined GAMG_STAGES
1161     {
1162       char str[32];
1163       sprintf(str,"MG Level %d (finest)",0);
1164       PetscLogStageRegister(str, &gamg_stages[0]);
1165       PetscInt lidx;
1166       for (lidx=1;lidx<9;lidx++){
1167 	sprintf(str,"MG Level %d",lidx);
1168 	PetscLogStageRegister(str, &gamg_stages[lidx]);
1169       }
1170     }
1171 #endif
1172   }
1173 #endif
1174   PetscFunctionReturn(0);
1175 }
1176 EXTERN_C_END
1177