xref: /petsc/src/ksp/pc/impls/gamg/gamg.c (revision 01fcfa61ba82d50520edb350abff422b828fc221)
1 /*
2  GAMG geometric-algebric multigrid PC - Mark Adams 2011
3  */
4 #include "private/matimpl.h"
5 #include <../src/ksp/pc/impls/gamg/gamg.h>           /*I "petscpc.h" I*/
6 #include <private/kspimpl.h>
7 
8 #if defined PETSC_USE_LOG
9 PetscLogEvent gamg_setup_events[NUM_SET];
10 #endif
11 #define GAMG_MAXLEVELS 30
12 
13 /* #define GAMG_STAGES */
14 #if (defined PETSC_USE_LOG && defined GAMG_STAGES)
15 static PetscLogStage gamg_stages[GAMG_MAXLEVELS];
16 #endif
17 
18 static PetscFList GAMGList = 0;
19 
20 /* ----------------------------------------------------------------------------- */
21 #undef __FUNCT__
22 #define __FUNCT__ "PCReset_GAMG"
23 PetscErrorCode PCReset_GAMG(PC pc)
24 {
25   PetscErrorCode  ierr;
26   PC_MG           *mg = (PC_MG*)pc->data;
27   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
28 
29   PetscFunctionBegin;
30   if( pc_gamg->data != 0 ) { /* this should not happen, cleaned up in SetUp */
31     ierr = PetscFree(pc_gamg->data); CHKERRQ(ierr);
32   }
33   pc_gamg->data = 0; pc_gamg->data_sz = 0;
34   PetscFunctionReturn(0);
35 }
36 
37 /* -------------------------------------------------------------------------- */
38 /*
39    createLevel: create coarse op with RAP.  repartition and/or reduce number
40      of active processors.
41 
42    Input Parameter:
43    . pc - parameters
44    . Amat_fine - matrix on this fine (k) level
45    . cbs - coarse block size
46    . isLast -
47    In/Output Parameter:
48    . a_P_inout - prolongation operator to the next level (k-1)
49    . a_nactive_proc - number of active procs
50    Output Parameter:
51    . a_Amat_crs - coarse matrix that is created (k-1)
52 */
53 
54 #undef __FUNCT__
55 #define __FUNCT__ "createLevel"
56 PetscErrorCode createLevel( const PC pc,
57                             const Mat Amat_fine,
58                             const PetscInt cbs,
59                             const PetscBool isLast,
60                             Mat *a_P_inout,
61                             PetscMPIInt *a_nactive_proc,
62                             Mat *a_Amat_crs
63                             )
64 {
65   PC_MG           *mg = (PC_MG*)pc->data;
66   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
67   const PetscBool  repart = pc_gamg->repart;
68   const PetscInt   min_eq_proc = pc_gamg->min_eq_proc, coarse_max = pc_gamg->coarse_eq_limit;
69   PetscErrorCode   ierr;
70   Mat              Cmat,Pnew,Pold=*a_P_inout;
71   IS               new_indices,isnum;
72   MPI_Comm         wcomm = ((PetscObject)Amat_fine)->comm;
73   PetscMPIInt      mype,npe,new_npe,nactive = *a_nactive_proc;
74   PetscInt         neq,NN,Istart,Iend,Istart0,Iend0,ncrs_new,ncrs0,rfactor;
75 
76   PetscFunctionBegin;
77   ierr = MPI_Comm_rank( wcomm, &mype ); CHKERRQ(ierr);
78   ierr = MPI_Comm_size( wcomm, &npe );  CHKERRQ(ierr);
79 
80   /* RAP */
81 #ifdef USE_R
82   /* make R wih brute force for now */
83   ierr = MatTranspose( Pold, Pnew );
84   ierr = MatDestroy( &Pold );  CHKERRQ(ierr);
85   ierr = MatRARt( Amat_fine, Pnew, MAT_INITIAL_MATRIX, 2.0, &Cmat ); CHKERRQ(ierr);
86   Pold = Pnew;
87 #else
88   ierr = MatPtAP( Amat_fine, Pold, MAT_INITIAL_MATRIX, 2.0, &Cmat ); CHKERRQ(ierr);
89 #endif
90   ierr = MatSetBlockSize( Cmat, cbs );      CHKERRQ(ierr);
91   ierr = MatGetOwnershipRange( Cmat, &Istart0, &Iend0 ); CHKERRQ(ierr);
92   ncrs0 = (Iend0-Istart0)/cbs; assert((Iend0-Istart0)%cbs == 0);
93 
94   /* get number of PEs to make active, reduce */
95   ierr = MatGetSize( Cmat, &neq, &NN );  CHKERRQ(ierr);
96   new_npe = (PetscMPIInt)((float)neq/(float)min_eq_proc + 0.5); /* hardwire min. number of eq/proc */
97   if( new_npe == 0 || neq < coarse_max ) new_npe = 1;
98   else if (new_npe >= nactive ) new_npe = nactive; /* no change, rare */
99   if( isLast ) new_npe = 1;
100 
101   if( !repart && new_npe==nactive ) {
102     *a_Amat_crs = Cmat; /* output - no repartitioning or reduction */
103   }
104   else {
105     /* Repartition Cmat_{k} and move colums of P^{k}_{k-1} and coordinates accordingly */
106     const PetscInt *idx,ndata_rows=pc_gamg->data_cell_rows,ndata_cols=pc_gamg->data_cell_cols,data_sz=ndata_rows*ndata_cols;
107     const PetscInt  stride0=ncrs0*pc_gamg->data_cell_rows;
108     PetscInt        *counts,is_sz,*newproc_idx,ii,jj,kk,strideNew,*tidx,inpe,targetPE;
109     IS              isnewproc;
110     VecScatter      vecscat;
111     PetscScalar    *array;
112     Vec             src_crd, dest_crd;
113     IS              isscat;
114 
115     ierr = PetscMalloc( npe*sizeof(PetscInt), &counts ); CHKERRQ(ierr);
116 #if defined PETSC_USE_LOG
117       ierr = PetscLogEventBegin(gamg_setup_events[SET12],0,0,0,0);CHKERRQ(ierr);
118 #endif
119     if( repart ) {
120       /* create sub communicator  */
121       Mat             adj;
122 
123       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s repartition: npe (active): %d --> %d, neq = %d\n",mype,__FUNCT__,*a_nactive_proc,new_npe,neq);
124 
125       /* MatPartitioningApply call MatConvert, which is collective */
126       if( cbs == 1 ) {
127 	ierr = MatConvert( Cmat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
128       }
129       else{
130 	/* make a scalar matrix to partition */
131 	Mat tMat;
132 	PetscInt ncols,jj,Ii;
133 	const PetscScalar *vals;
134 	const PetscInt *idx;
135 	PetscInt *d_nnz, *o_nnz;
136 	static PetscInt llev = 0;
137 
138 	ierr = PetscMalloc( ncrs0*sizeof(PetscInt), &d_nnz ); CHKERRQ(ierr);
139 	ierr = PetscMalloc( ncrs0*sizeof(PetscInt), &o_nnz ); CHKERRQ(ierr);
140 	for ( Ii = Istart0, jj = 0 ; Ii < Iend0 ; Ii += cbs, jj++ ) {
141 	  ierr = MatGetRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
142 	  d_nnz[jj] = ncols/cbs;
143 	  o_nnz[jj] = ncols/cbs;
144 	  ierr = MatRestoreRow(Cmat,Ii,&ncols,0,0); CHKERRQ(ierr);
145 	  if( d_nnz[jj] > ncrs0 ) d_nnz[jj] = ncrs0;
146 	  if( o_nnz[jj] > (neq/cbs-ncrs0) ) o_nnz[jj] = neq/cbs-ncrs0;
147 	}
148 
149 	ierr = MatCreateMPIAIJ( wcomm, ncrs0, ncrs0,
150 				PETSC_DETERMINE, PETSC_DETERMINE,
151 				0, d_nnz, 0, o_nnz,
152 				&tMat );
153 	CHKERRQ(ierr);
154 	ierr = PetscFree( d_nnz ); CHKERRQ(ierr);
155 	ierr = PetscFree( o_nnz ); CHKERRQ(ierr);
156 
157 	for ( ii = Istart0; ii < Iend0; ii++ ) {
158 	  PetscInt dest_row = ii/cbs;
159 	  ierr = MatGetRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
160 	  for( jj = 0 ; jj < ncols ; jj++ ){
161 	    PetscInt dest_col = idx[jj]/cbs;
162 	    PetscScalar v = 1.0;
163 	    ierr = MatSetValues(tMat,1,&dest_row,1,&dest_col,&v,ADD_VALUES); CHKERRQ(ierr);
164 	  }
165 	  ierr = MatRestoreRow(Cmat,ii,&ncols,&idx,&vals); CHKERRQ(ierr);
166 	}
167 	ierr = MatAssemblyBegin(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
168 	ierr = MatAssemblyEnd(tMat,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
169 
170 	if( llev++ == -1 ) {
171 	  PetscViewer viewer; char fname[32];
172 	  sprintf(fname,"part_mat_%d.mat",llev);
173 	  PetscViewerBinaryOpen(wcomm,fname,FILE_MODE_WRITE,&viewer);
174 	  ierr = MatView( tMat, viewer ); CHKERRQ(ierr);
175 	  ierr = PetscViewerDestroy( &viewer );
176 	}
177 
178 	ierr = MatConvert( tMat, MATMPIADJ, MAT_INITIAL_MATRIX, &adj );   CHKERRQ(ierr);
179 
180 	ierr = MatDestroy( &tMat );  CHKERRQ(ierr);
181       }
182 
183       { /* partition: get newproc_idx, set is_sz */
184 	char prefix[256];
185 	const char *pcpre;
186 	const PetscInt *is_idx;
187 	MatPartitioning  mpart;
188 	IS proc_is;
189 
190 	ierr = MatPartitioningCreate( wcomm, &mpart ); CHKERRQ(ierr);
191 	ierr = MatPartitioningSetAdjacency( mpart, adj ); CHKERRQ(ierr);
192 	ierr = PCGetOptionsPrefix( pc, &pcpre );CHKERRQ(ierr);
193 	ierr = PetscSNPrintf(prefix,sizeof prefix,"%spc_gamg_",pcpre?pcpre:"");CHKERRQ(ierr);
194 	ierr = PetscObjectSetOptionsPrefix((PetscObject)mpart,prefix);CHKERRQ(ierr);
195 	ierr = MatPartitioningSetFromOptions( mpart );    CHKERRQ(ierr);
196 	ierr = MatPartitioningSetNParts( mpart, new_npe );CHKERRQ(ierr);
197 	ierr = MatPartitioningApply( mpart, &proc_is ); CHKERRQ(ierr);
198 	ierr = MatPartitioningDestroy( &mpart );          CHKERRQ(ierr);
199 
200 	/* collect IS info */
201 	ierr = ISGetLocalSize( proc_is, &is_sz );       CHKERRQ(ierr);
202 	ierr = PetscMalloc( cbs*is_sz*sizeof(PetscInt), &newproc_idx ); CHKERRQ(ierr);
203 	ierr = ISGetIndices( proc_is, &is_idx );        CHKERRQ(ierr);
204 	NN = 1; /* bring to "front" of machine */
205 	/*NN = npe/new_npe;*/ /* spread partitioning across machine */
206 	for( kk = jj = 0 ; kk < is_sz ; kk++ ){
207 	  for( ii = 0 ; ii < cbs ; ii++, jj++ ){
208 	    newproc_idx[jj] = is_idx[kk] * NN; /* distribution */
209 	  }
210 	}
211 	ierr = ISRestoreIndices( proc_is, &is_idx );     CHKERRQ(ierr);
212 	ierr = ISDestroy( &proc_is );                    CHKERRQ(ierr);
213 
214 	is_sz *= cbs;
215       }
216       ierr = MatDestroy( &adj );                       CHKERRQ(ierr);
217 
218       ierr = ISCreateGeneral( wcomm, is_sz, newproc_idx, PETSC_COPY_VALUES, &isnewproc );
219       CHKERRQ(ierr);
220       if( newproc_idx != 0 ) {
221 	ierr = PetscFree( newproc_idx );  CHKERRQ(ierr);
222       }
223     }
224     else { /* simple aggreagtion of parts */
225       /* find factor */
226       if( new_npe == 1 ) rfactor = npe; /* easy */
227       else {
228 	PetscReal best_fact = 0.;
229 	jj = -1;
230 	for( kk = 1 ; kk <= npe ; kk++ ){
231 	  if( npe%kk==0 ) { /* a candidate */
232 	    PetscReal nactpe = (PetscReal)npe/(PetscReal)kk, fact = nactpe/(PetscReal)new_npe;
233 	    if(fact > 1.0) fact = 1./fact; /* keep fact < 1 */
234 	    if( fact > best_fact ) {
235 	      best_fact = fact; jj = kk;
236 	    }
237 	  }
238 	}
239 	if(jj!=-1) rfactor = jj;
240 	else rfactor = 1; /* prime? */
241       }
242       new_npe = npe/rfactor;
243 
244       if( new_npe==nactive ) {
245 	*a_Amat_crs = Cmat; /* output - no repartitioning or reduction */
246 	ierr = PetscFree( counts );  CHKERRQ(ierr);
247 	*a_nactive_proc = new_npe; /* output */
248 	if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s aggregate processors noop: new_npe=%d, neq=%d\n",mype,__FUNCT__,new_npe,neq);
249 	PetscFunctionReturn(0);
250       }
251 
252       /* reduce - isnewproc */
253       targetPE = mype/rfactor;
254 
255       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s aggregate processors: npe: %d --> %d, neq=%d\n",mype,__FUNCT__,*a_nactive_proc,new_npe,neq);
256       is_sz = ncrs0*cbs;
257       ierr = ISCreateStride( wcomm, is_sz, targetPE, 0, &isnewproc );
258       CHKERRQ(ierr);
259     }
260 
261     /*
262       Create an index set from the isnewproc index set to indicate the mapping TO
263     */
264     ierr = ISPartitioningToNumbering( isnewproc, &isnum ); CHKERRQ(ierr);
265     /*
266       Determine how many elements are assigned to each processor
267     */
268     inpe = npe;
269     ierr = ISPartitioningCount( isnewproc, inpe, counts ); CHKERRQ(ierr);
270     ierr = ISDestroy( &isnewproc );                       CHKERRQ(ierr);
271     ncrs_new = counts[mype]/cbs;
272     strideNew = ncrs_new*ndata_rows;
273 #if defined PETSC_USE_LOG
274       ierr = PetscLogEventEnd(gamg_setup_events[SET12],0,0,0,0);   CHKERRQ(ierr);
275 #endif
276     /* Create a vector to contain the newly ordered element information */
277     ierr = VecCreate( wcomm, &dest_crd );
278     ierr = VecSetSizes( dest_crd, data_sz*ncrs_new, PETSC_DECIDE ); CHKERRQ(ierr);
279     ierr = VecSetFromOptions( dest_crd ); CHKERRQ(ierr); /* this is needed! */
280     /*
281      There are 'ndata_rows*ndata_cols' data items per node, (one can think of the vectors of having
282      a block size of ...).  Note, ISs are expanded into equation space by 'cbs'.
283      */
284     ierr = PetscMalloc( (ncrs0*data_sz)*sizeof(PetscInt), &tidx ); CHKERRQ(ierr);
285     ierr = ISGetIndices( isnum, &idx ); CHKERRQ(ierr);
286     for(ii=0,jj=0; ii<ncrs0 ; ii++) {
287       PetscInt id = idx[ii*cbs]/cbs; /* get node back */
288       for( kk=0; kk<data_sz ; kk++, jj++) tidx[jj] = id*data_sz + kk;
289     }
290     ierr = ISRestoreIndices( isnum, &idx ); CHKERRQ(ierr);
291     ierr = ISCreateGeneral( wcomm, data_sz*ncrs0, tidx, PETSC_COPY_VALUES, &isscat );
292     CHKERRQ(ierr);
293     ierr = PetscFree( tidx );  CHKERRQ(ierr);
294     /*
295      Create a vector to contain the original vertex information for each element
296      */
297     ierr = VecCreateSeq( PETSC_COMM_SELF, data_sz*ncrs0, &src_crd ); CHKERRQ(ierr);
298     for( jj=0; jj<ndata_cols ; jj++ ) {
299       for( ii=0 ; ii<ncrs0 ; ii++) {
300 	for( kk=0; kk<ndata_rows ; kk++ ) {
301 	  PetscInt ix = ii*ndata_rows + kk + jj*stride0, jx = ii*data_sz + kk*ndata_cols + jj;
302           PetscScalar tt = (PetscScalar)pc_gamg->data[ix];
303 	  ierr = VecSetValues( src_crd, 1, &jx, &tt, INSERT_VALUES );  CHKERRQ(ierr);
304 	}
305       }
306     }
307     ierr = VecAssemblyBegin(src_crd); CHKERRQ(ierr);
308     ierr = VecAssemblyEnd(src_crd); CHKERRQ(ierr);
309     /*
310       Scatter the element vertex information (still in the original vertex ordering)
311       to the correct processor
312     */
313     ierr = VecScatterCreate( src_crd, PETSC_NULL, dest_crd, isscat, &vecscat);
314     CHKERRQ(ierr);
315     ierr = ISDestroy( &isscat );       CHKERRQ(ierr);
316     ierr = VecScatterBegin(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
317     ierr = VecScatterEnd(vecscat,src_crd,dest_crd,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
318     ierr = VecScatterDestroy( &vecscat );       CHKERRQ(ierr);
319     ierr = VecDestroy( &src_crd );       CHKERRQ(ierr);
320     /*
321       Put the element vertex data into a new allocation of the gdata->ele
322     */
323     ierr = PetscFree( pc_gamg->data );    CHKERRQ(ierr);
324     ierr = PetscMalloc( data_sz*ncrs_new*sizeof(PetscReal), &pc_gamg->data );    CHKERRQ(ierr);
325     pc_gamg->data_sz = data_sz*ncrs_new;
326     ierr = VecGetArray( dest_crd, &array );    CHKERRQ(ierr);
327     for( jj=0; jj<ndata_cols ; jj++ ) {
328       for( ii=0 ; ii<ncrs_new ; ii++) {
329 	for( kk=0; kk<ndata_rows ; kk++ ) {
330 	  PetscInt ix = ii*ndata_rows + kk + jj*strideNew, jx = ii*data_sz + kk*ndata_cols + jj;
331 	  pc_gamg->data[ix] = PetscRealPart(array[jx]);
332 	  array[jx] = 1.e300;
333 	}
334       }
335     }
336     ierr = VecRestoreArray( dest_crd, &array );    CHKERRQ(ierr);
337     ierr = VecDestroy( &dest_crd );    CHKERRQ(ierr);
338 #if defined PETSC_USE_LOG
339     ierr = PetscLogEventBegin(gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
340 #endif
341     /*
342       Invert for MatGetSubMatrix
343     */
344     ierr = ISInvertPermutation( isnum, ncrs_new*cbs, &new_indices ); CHKERRQ(ierr);
345     ierr = ISSort( new_indices ); CHKERRQ(ierr); /* is this needed? */
346     ierr = ISDestroy( &isnum ); CHKERRQ(ierr);
347 #if defined PETSC_USE_LOG
348     ierr = PetscLogEventEnd(gamg_setup_events[SET13],0,0,0,0);CHKERRQ(ierr);
349     ierr = PetscLogEventBegin(gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
350 #endif
351     /* A_crs output */
352     ierr = MatGetSubMatrix( Cmat, new_indices, new_indices, MAT_INITIAL_MATRIX, a_Amat_crs );
353     CHKERRQ(ierr);
354 
355     ierr = MatDestroy( &Cmat ); CHKERRQ(ierr);
356     Cmat = *a_Amat_crs; /* output */
357     ierr = MatSetBlockSize( Cmat, cbs );      CHKERRQ(ierr);
358 #if defined PETSC_USE_LOG
359     ierr = PetscLogEventEnd(gamg_setup_events[SET14],0,0,0,0);CHKERRQ(ierr);
360 #endif
361     /* prolongator */
362     ierr = MatGetOwnershipRange( Pold, &Istart, &Iend );    CHKERRQ(ierr);
363     {
364       IS findices;
365 #if defined PETSC_USE_LOG
366       ierr = PetscLogEventBegin(gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
367 #endif
368       ierr = ISCreateStride(wcomm,Iend-Istart,Istart,1,&findices);   CHKERRQ(ierr);
369 #ifdef USE_R
370       ierr = MatGetSubMatrix( Pold, new_indices, findices, MAT_INITIAL_MATRIX, &Pnew );
371 #else
372       ierr = MatGetSubMatrix( Pold, findices, new_indices, MAT_INITIAL_MATRIX, &Pnew );
373 #endif
374       CHKERRQ(ierr);
375       ierr = ISDestroy( &findices ); CHKERRQ(ierr);
376 #if defined PETSC_USE_LOG
377       ierr = PetscLogEventEnd(gamg_setup_events[SET15],0,0,0,0);CHKERRQ(ierr);
378 #endif
379     }
380     ierr = MatDestroy( a_P_inout ); CHKERRQ(ierr);
381     *a_P_inout = Pnew; /* output - repartitioned */
382     ierr = ISDestroy( &new_indices ); CHKERRQ(ierr);
383     ierr = PetscFree( counts );  CHKERRQ(ierr);
384   }
385 
386   *a_nactive_proc = new_npe; /* output */
387 
388   if( !PETSC_TRUE ) {
389     PetscViewer viewer; char fname[32]; static int llev=0; Cmat = *a_Amat_crs;
390     if(llev==0) {
391       sprintf(fname,"Cmat_%d.m",llev++);
392       PetscViewerASCIIOpen(wcomm,fname,&viewer);
393       ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
394       ierr = MatView(Amat_fine, viewer ); CHKERRQ(ierr);
395       ierr = PetscViewerDestroy( &viewer );
396     }
397     sprintf(fname,"Cmat_%d.m",llev++);
398     PetscViewerASCIIOpen(wcomm,fname,&viewer);
399     ierr = PetscViewerSetFormat( viewer, PETSC_VIEWER_ASCII_MATLAB);  CHKERRQ(ierr);
400     ierr = MatView(Cmat, viewer ); CHKERRQ(ierr);
401     ierr = PetscViewerDestroy( &viewer );
402   }
403 
404   PetscFunctionReturn(0);
405 }
406 
407 /* -------------------------------------------------------------------------- */
408 /*
409    PCSetUp_GAMG - Prepares for the use of the GAMG preconditioner
410                     by setting data structures and options.
411 
412    Input Parameter:
413 .  pc - the preconditioner context
414 
415    Application Interface Routine: PCSetUp()
416 
417    Notes:
418    The interface routine PCSetUp() is not usually called directly by
419    the user, but instead is called by PCApply() if necessary.
420 */
421 #undef __FUNCT__
422 #define __FUNCT__ "PCSetUp_GAMG"
423 PetscErrorCode PCSetUp_GAMG( PC pc )
424 {
425   PetscErrorCode  ierr;
426   PC_MG           *mg = (PC_MG*)pc->data;
427   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
428   PC_MG_Levels   **mglevels = mg->levels;
429   Mat              Pmat = pc->pmat;
430   PetscInt         fine_level,level,level1,M,N,bs,nloc,lidx,Istart,Iend;
431   MPI_Comm         wcomm = ((PetscObject)pc)->comm;
432   PetscMPIInt      mype,npe,nactivepe;
433   Mat              Aarr[GAMG_MAXLEVELS], Parr[GAMG_MAXLEVELS];
434   PetscReal        emaxs[GAMG_MAXLEVELS];
435   PetscLogDouble   nnz0,nnztot;
436   MatInfo          info;
437 
438   PetscFunctionBegin;
439   pc_gamg->setup_count++;
440   if( pc->setupcalled > 0 ) {
441     /* just do Galerkin grids */
442     Mat B,dA,dB;
443 
444     /* PCSetUp_MG seems to insists on setting this to GMRES */
445     ierr = KSPSetType( mglevels[0]->smoothd, KSPPREONLY ); CHKERRQ(ierr);
446 
447     if( pc_gamg->Nlevels > 1 ) {
448       /* currently only handle case where mat and pmat are the same on coarser levels */
449       ierr = KSPGetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,&dA,&dB,PETSC_NULL);CHKERRQ(ierr);
450       /* (re)set to get dirty flag */
451       ierr = KSPSetOperators(mglevels[pc_gamg->Nlevels-1]->smoothd,dA,dB,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
452       ierr = KSPSetUp( mglevels[pc_gamg->Nlevels-1]->smoothd ); CHKERRQ(ierr);
453 
454       for (level=pc_gamg->Nlevels-2; level>-1; level--) {
455         ierr = KSPGetOperators(mglevels[level]->smoothd,PETSC_NULL,&B,PETSC_NULL);CHKERRQ(ierr);
456         /* the first time through the matrix structure has changed from repartitioning */
457         if( pc_gamg->setup_count == 2 ) {
458           ierr = MatDestroy( &B );  CHKERRQ(ierr);
459           ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_INITIAL_MATRIX,1.0,&B);CHKERRQ(ierr);
460           mglevels[level]->A = B;
461         }
462         else {
463           ierr = MatPtAP(dB,mglevels[level+1]->interpolate,MAT_REUSE_MATRIX,1.0,&B);CHKERRQ(ierr);
464         }
465         ierr = KSPSetOperators(mglevels[level]->smoothd,B,B,SAME_NONZERO_PATTERN); CHKERRQ(ierr);
466         dB = B;
467         /* setup KSP/PC */
468         ierr = KSPSetUp( mglevels[level]->smoothd ); CHKERRQ(ierr);
469       }
470     }
471 
472     pc->setupcalled = 2;
473 
474     PetscFunctionReturn(0);
475   }
476 
477   ierr = MPI_Comm_rank(wcomm,&mype);CHKERRQ(ierr);
478   ierr = MPI_Comm_size(wcomm,&npe);CHKERRQ(ierr);
479   /* GAMG requires input of fine-grid matrix. It determines nlevels. */
480   ierr = MatGetBlockSize( Pmat, &bs ); CHKERRQ(ierr);
481   ierr = MatGetSize( Pmat, &M, &N );CHKERRQ(ierr);
482   ierr = MatGetOwnershipRange( Pmat, &Istart, &Iend ); CHKERRQ(ierr);
483   nloc = (Iend-Istart)/bs; assert((Iend-Istart)%bs == 0);
484 
485   if( pc_gamg->data == 0 && nloc > 0 ) {
486     if(!pc_gamg->createdefaultdata){
487       SETERRQ(((PetscObject)pc)->comm,PETSC_ERR_LIB,"'createdefaultdata' not set?!?! need to support NULL data!!!");
488     }
489     ierr = pc_gamg->createdefaultdata( pc ); CHKERRQ(ierr);
490   }
491 
492   /* Get A_i and R_i */
493   if (pc_gamg->verbose) {
494     if(pc_gamg->verbose==1) ierr =  MatGetInfo(Pmat,MAT_LOCAL,&info);
495     else ierr =  MatGetInfo(Pmat,MAT_GLOBAL_SUM,&info);
496     CHKERRQ(ierr);
497     nnz0 = info.nz_used;
498     nnztot = info.nz_used;
499     PetscPrintf(wcomm,"\t[%d]%s level %d N=%d, n data rows=%d, n data cols=%d, nnz/row (ave)=%d, np=%d\n",
500                 mype,__FUNCT__,0,N,pc_gamg->data_cell_rows,pc_gamg->data_cell_cols,
501                 (int)(nnz0/(PetscReal)N),npe);
502   }
503   for ( level=0, Aarr[0] = Pmat, nactivepe = npe; /* hard wired stopping logic */
504         level < (pc_gamg->Nlevels-1) && (level==0 || M>pc_gamg->coarse_eq_limit); /* && (npe==1 || nactivepe>1); */
505         level++ ){
506     level1 = level + 1;
507 #if (defined PETSC_USE_LOG && defined GAMG_STAGES)
508     ierr = PetscLogStagePush(gamg_stages[level]); CHKERRQ( ierr );
509 #endif
510 #if defined PETSC_USE_LOG
511     ierr = PetscLogEventBegin(gamg_setup_events[SET1],0,0,0,0); CHKERRQ(ierr);
512 #endif
513     { /* construct prolongator */
514       Mat Gmat;   assert(pc_gamg->graph);
515       IS selected, llist;   assert(pc_gamg->coarsen);
516 
517       ierr = pc_gamg->graph( pc, Aarr[level], &Gmat ); CHKERRQ(ierr);
518       ierr = pc_gamg->coarsen( pc, Gmat, &selected, &llist ); CHKERRQ(ierr);
519       ierr = pc_gamg->prolongator( pc, Aarr[level], Gmat, selected, llist, &Parr[level1] );
520       CHKERRQ(ierr);
521 
522       if( Parr[level1] ){
523           /* get new block size of coarse matrices */
524         if( pc_gamg->col_bs_id != -1 ){
525           PetscBool flag;
526           ierr = PetscObjectComposedDataGetInt( (PetscObject)Parr[level1], pc_gamg->col_bs_id, bs, flag );
527           CHKERRQ( ierr ); assert(flag);
528         }
529       }
530 
531       if( pc_gamg->optprol && Parr[level1] ){
532         /* smooth */
533         ierr = pc_gamg->optprol( pc, Aarr[level], &Parr[level1] ); CHKERRQ(ierr);
534       }
535 
536       ierr = MatDestroy( &Gmat );  CHKERRQ(ierr);
537       ierr = ISDestroy( &selected );  CHKERRQ(ierr);
538       ierr = ISDestroy( &llist );  CHKERRQ(ierr);
539     }
540 #if defined PETSC_USE_LOG
541     ierr = PetscLogEventEnd(gamg_setup_events[SET1],0,0,0,0);CHKERRQ(ierr);
542 #endif
543     /* cache eigen estimate */
544     if( pc_gamg->emax_id != -1 ){
545       PetscBool flag;
546       ierr = PetscObjectComposedDataGetReal( (PetscObject)Aarr[level], pc_gamg->emax_id, emaxs[level], flag );
547       CHKERRQ( ierr );
548       if( !flag ) emaxs[level] = -1.;
549     }
550     else emaxs[level] = -1.;
551     if(level==0) Aarr[0] = Pmat; /* use Pmat for finest level setup */
552     if( !Parr[level1] ) {
553       if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s stop gridding, level %d\n",mype,__FUNCT__,level);
554       break;
555     }
556 #if defined PETSC_USE_LOG
557     ierr = PetscLogEventBegin(gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
558 #endif
559     ierr = createLevel( pc, Aarr[level], bs,
560                         (PetscBool)(level==pc_gamg->Nlevels-2),
561                         &Parr[level1], &nactivepe, &Aarr[level1] );
562     CHKERRQ(ierr);
563 #if defined PETSC_USE_LOG
564     ierr = PetscLogEventEnd(gamg_setup_events[SET2],0,0,0,0);CHKERRQ(ierr);
565 #endif
566     ierr = MatGetSize( Aarr[level1], &M, &N );CHKERRQ(ierr);
567     ierr = MatGetInfo( Aarr[level1], MAT_GLOBAL_SUM, &info ); CHKERRQ(ierr);
568     if (pc_gamg->verbose){
569       PetscPrintf(wcomm,"\t\t[%d]%s %d) N=%d, n data cols=%d, nnz/row (ave)=%d, %d active pes\n",
570                   mype,__FUNCT__,(int)level1,N,pc_gamg->data_cell_cols,
571                   (int)(info.nz_used/(PetscReal)N),nactivepe);
572     }
573     /* stop if one node */
574     if( M/pc_gamg->data_cell_cols < 2 ) {
575       level++;
576       break;
577     }
578     /* Vec diag; PetscScalar *data_arr,v; PetscInt Istart,Iend,kk,nloceq,id; */
579     /* v = 1.e-10; /\* LU factor has hard wired numbers for small diags so this needs to match (yuk) *\/ */
580     /* ierr = MatGetOwnershipRange(Aarr[level1], &Istart, &Iend); CHKERRQ(ierr); */
581     /* nloceq = Iend-Istart; */
582     /* ierr = MatGetVecs( Aarr[level1], &diag, 0 );    CHKERRQ(ierr); */
583     /* ierr = MatGetDiagonal( Aarr[level1], diag );    CHKERRQ(ierr); */
584     /* ierr = VecGetArray( diag, &data_arr );   CHKERRQ(ierr); */
585     /* for(kk=0;kk<nloceq;kk++){ */
586     /*   if(data_arr[kk]==0.0) { */
587     /*     id = kk + Istart; */
588     /*     ierr = MatSetValues(Aarr[level1],1,&id,1,&id,&v,INSERT_VALUES); */
589     /*     CHKERRQ(ierr); */
590     /*     PetscPrintf(PETSC_COMM_SELF,"\t[%d]%s warning: added zero to diag (%d) on level %d \n",mype,__FUNCT__,id,level1); */
591     /*   } */
592     /* } */
593     /* ierr = VecRestoreArray( diag, &data_arr ); CHKERRQ(ierr); */
594     /* ierr = VecDestroy( &diag );                CHKERRQ(ierr); */
595     ierr = MatAssemblyBegin(Aarr[level1],MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
596     ierr = MatAssemblyEnd(Aarr[level1],MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
597 
598 #if (defined PETSC_USE_LOG && defined GAMG_STAGES)
599     ierr = PetscLogStagePop(); CHKERRQ( ierr );
600 #endif
601     if(pc_gamg->verbose){
602       if(pc_gamg->verbose==1) ierr =  MatGetInfo(Aarr[level1],MAT_LOCAL,&info);
603       else ierr =  MatGetInfo(Aarr[level1],MAT_GLOBAL_SUM,&info);
604       CHKERRQ(ierr);
605       nnztot += info.nz_used;
606     }
607   } /* levels */
608 
609   if( pc_gamg->data ) {
610     ierr = PetscFree( pc_gamg->data ); CHKERRQ( ierr );
611     pc_gamg->data = 0;
612   }
613 
614   if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s %d levels, grid compexity = %g\n",0,__FUNCT__,level+1,nnztot/nnz0);
615   pc_gamg->Nlevels = level + 1;
616   fine_level = level;
617   ierr = PCMGSetLevels(pc,pc_gamg->Nlevels,PETSC_NULL);CHKERRQ(ierr);
618 
619   if( pc_gamg->Nlevels > 1 ) { /* don't setup MG if  */
620   /* set default smoothers */
621   for ( lidx = 1, level = pc_gamg->Nlevels-2;
622         lidx <= fine_level;
623         lidx++, level--) {
624     PetscReal emax, emin;
625     KSP smoother; PC subpc;
626     PetscBool isCheb;
627     /* set defaults */
628     ierr = PCMGGetSmoother( pc, lidx, &smoother ); CHKERRQ(ierr);
629     ierr = KSPSetType( smoother, KSPCHEBYCHEV );CHKERRQ(ierr);
630     ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
631     /* ierr = KSPSetTolerances(smoother,PETSC_DEFAULT,PETSC_DEFAULT,PETSC_DEFAULT,2); CHKERRQ(ierr); */
632     ierr = PCSetType( subpc, PCJACOBI ); CHKERRQ(ierr);
633     ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
634     /* overide defaults with input parameters */
635     ierr = KSPSetFromOptions( smoother ); CHKERRQ(ierr);
636 
637     ierr = KSPSetOperators( smoother, Aarr[level], Aarr[level], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
638     /* do my own cheby */
639     ierr = PetscTypeCompare( (PetscObject)smoother, KSPCHEBYCHEV, &isCheb ); CHKERRQ(ierr);
640 
641     if( isCheb ) {
642       ierr = PetscTypeCompare( (PetscObject)subpc, PCJACOBI, &isCheb ); CHKERRQ(ierr);
643       if( isCheb && emaxs[level] > 0.0 ) emax=emaxs[level]; /* eigen estimate only for diagnal PC */
644       else{ /* eigen estimate 'emax' */
645         KSP eksp; Mat Lmat = Aarr[level];
646         Vec bb, xx;
647 
648         ierr = MatGetVecs( Lmat, &bb, 0 );         CHKERRQ(ierr);
649         ierr = MatGetVecs( Lmat, &xx, 0 );         CHKERRQ(ierr);
650         {
651           PetscRandom    rctx;
652           ierr = PetscRandomCreate(wcomm,&rctx);CHKERRQ(ierr);
653           ierr = PetscRandomSetFromOptions(rctx);CHKERRQ(ierr);
654           ierr = VecSetRandom(bb,rctx);CHKERRQ(ierr);
655           ierr = PetscRandomDestroy( &rctx ); CHKERRQ(ierr);
656         }
657         ierr = KSPCreate(wcomm,&eksp);CHKERRQ(ierr);
658         ierr = KSPSetTolerances( eksp, PETSC_DEFAULT, PETSC_DEFAULT, PETSC_DEFAULT, 10 );
659         CHKERRQ(ierr);
660         ierr = KSPSetNormType( eksp, KSP_NORM_NONE );                 CHKERRQ(ierr);
661 
662         ierr = KSPAppendOptionsPrefix( eksp, "est_");         CHKERRQ(ierr);
663         ierr = KSPSetFromOptions( eksp );    CHKERRQ(ierr);
664 
665         ierr = KSPSetInitialGuessNonzero( eksp, PETSC_FALSE ); CHKERRQ(ierr);
666         ierr = KSPSetOperators( eksp, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ( ierr );
667         ierr = KSPSetComputeSingularValues( eksp,PETSC_TRUE ); CHKERRQ(ierr);
668 
669         { /* set PC type to be same as smoother - does not get all parameters!!! */
670           const PCType type;    PC pc;
671           ierr = PCGetType( subpc, &type );   CHKERRQ(ierr);
672           ierr = KSPGetPC( eksp, &pc );CHKERRQ( ierr );
673           ierr = PCSetType( pc, type ); CHKERRQ(ierr);
674         }
675 
676 	/* solve - keep stuff out of logging */
677 	ierr = PetscLogEventDeactivate(KSP_Solve);CHKERRQ(ierr);
678 	ierr = PetscLogEventDeactivate(PC_Apply);CHKERRQ(ierr);
679         ierr = KSPSolve( eksp, bb, xx ); CHKERRQ(ierr);
680 	ierr = PetscLogEventActivate(KSP_Solve);CHKERRQ(ierr);
681 	ierr = PetscLogEventActivate(PC_Apply);CHKERRQ(ierr);
682 
683         ierr = KSPComputeExtremeSingularValues( eksp, &emax, &emin ); CHKERRQ(ierr);
684 
685         ierr = VecDestroy( &xx );       CHKERRQ(ierr);
686         ierr = VecDestroy( &bb );       CHKERRQ(ierr);
687         ierr = KSPDestroy( &eksp );       CHKERRQ(ierr);
688 
689         if (pc_gamg->verbose) {
690           PetscPrintf(wcomm,"\t\t\t%s PC setup max eigen=%e min=%e\n",__FUNCT__,emax,emin);
691         }
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         /* heuristic - is this crap? */
698         emin = 1.*emax/((PetscReal)N1/(PetscReal)N0);
699         emax *= 1.05;
700       }
701       ierr = KSPChebychevSetEigenvalues( smoother, emax, emin );CHKERRQ(ierr);
702     }
703   }
704   {
705     /* coarse grid */
706     KSP smoother,*k2; PC subpc,pc2; PetscInt ii,first;
707     Mat Lmat = Aarr[pc_gamg->Nlevels-1];
708     ierr = PCMGGetSmoother( pc, 0, &smoother ); CHKERRQ(ierr);
709     ierr = KSPSetOperators( smoother, Lmat, Lmat, SAME_NONZERO_PATTERN ); CHKERRQ(ierr);
710     ierr = KSPSetNormType( smoother, KSP_NORM_NONE ); CHKERRQ(ierr);
711     ierr = KSPGetPC( smoother, &subpc ); CHKERRQ(ierr);
712     ierr = PCSetType( subpc, PCBJACOBI ); CHKERRQ(ierr);
713     ierr = PCSetUp( subpc ); CHKERRQ(ierr);
714     ierr = PCBJacobiGetSubKSP(subpc,&ii,&first,&k2);CHKERRQ(ierr);
715     assert(ii==1);
716     ierr = KSPGetPC(k2[0],&pc2);CHKERRQ(ierr);
717     ierr = PCSetType( pc2, PCLU ); CHKERRQ(ierr);
718   }
719 
720   /* should be called in PCSetFromOptions_GAMG(), but cannot be called prior to PCMGSetLevels() */
721   ierr = PetscObjectOptionsBegin((PetscObject)pc);CHKERRQ(ierr);
722   ierr = PCSetFromOptions_MG(pc); CHKERRQ(ierr);
723   ierr = PetscOptionsEnd();CHKERRQ(ierr);
724   if (mg->galerkin != 2) SETERRQ(wcomm,PETSC_ERR_USER,"GAMG does Galerkin manually so the -pc_mg_galerkin option must not be used.");
725 
726   /* set interpolation between the levels, clean up */
727   for (lidx=0,level=pc_gamg->Nlevels-1;
728        lidx<fine_level;
729        lidx++, level--){
730     ierr = PCMGSetInterpolation( pc, lidx+1, Parr[level] );CHKERRQ(ierr);
731     ierr = MatDestroy( &Parr[level] );  CHKERRQ(ierr);
732     ierr = MatDestroy( &Aarr[level] );  CHKERRQ(ierr);
733   }
734 
735   /* setupcalled is set to 0 so that MG is setup from scratch */
736   pc->setupcalled = 0;
737   ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
738   pc->setupcalled = 1; /* use 1 as signal that this has not been re-setup */
739 
740   {
741     KSP smoother;  /* PCSetUp_MG seems to insists on setting this to GMRES on coarse grid */
742     ierr = PCMGGetSmoother( pc, 0, &smoother ); CHKERRQ(ierr);
743     ierr = KSPSetType( smoother, KSPPREONLY ); CHKERRQ(ierr);
744     ierr = KSPSetUp( smoother ); CHKERRQ(ierr);
745   }
746   }
747   else {
748     KSP smoother;
749     if (pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s one level solver used (system is seen as DD). Using default solver.\n",mype,__FUNCT__);
750     ierr = PCMGGetSmoother( pc, 0, &smoother ); CHKERRQ(ierr);
751     ierr = KSPSetOperators( smoother, Aarr[0], Aarr[0], SAME_NONZERO_PATTERN );   CHKERRQ(ierr);
752     ierr = KSPSetType( smoother, KSPPREONLY ); CHKERRQ(ierr);
753     /* setupcalled is set to 0 so that MG is setup from scratch */
754     pc->setupcalled = 0;
755     ierr = PCSetUp_MG( pc );CHKERRQ( ierr );
756     pc->setupcalled = 1; /* use 1 as signal that this has not been re-setup */
757   }
758   PetscFunctionReturn(0);
759 }
760 
761 /* ------------------------------------------------------------------------- */
762 /*
763    PCDestroy_GAMG - Destroys the private context for the GAMG preconditioner
764    that was created with PCCreate_GAMG().
765 
766    Input Parameter:
767 .  pc - the preconditioner context
768 
769    Application Interface Routine: PCDestroy()
770 */
771 #undef __FUNCT__
772 #define __FUNCT__ "PCDestroy_GAMG"
773 PetscErrorCode PCDestroy_GAMG( PC pc )
774 {
775   PetscErrorCode  ierr;
776   PC_MG           *mg = (PC_MG*)pc->data;
777   PC_GAMG         *pc_gamg= (PC_GAMG*)mg->innerctx;
778 
779   PetscFunctionBegin;
780   ierr = PCReset_GAMG( pc );CHKERRQ(ierr);
781   ierr = PetscFree( pc_gamg );CHKERRQ(ierr);
782   ierr = PCDestroy_MG( pc );CHKERRQ(ierr);
783   PetscFunctionReturn(0);
784 }
785 
786 
787 #undef __FUNCT__
788 #define __FUNCT__ "PCGAMGSetProcEqLim"
789 /*@
790    PCGAMGSetProcEqLim - Set number of equations to aim for on coarse grids via
791    processor reduction.
792 
793    Not Collective on PC
794 
795    Input Parameters:
796 .  pc - the preconditioner context
797 
798 
799    Options Database Key:
800 .  -pc_gamg_process_eq_limit
801 
802    Level: intermediate
803 
804    Concepts: Unstructured multrigrid preconditioner
805 
806 .seealso: ()
807 @*/
808 PetscErrorCode  PCGAMGSetProcEqLim(PC pc, PetscInt n)
809 {
810   PetscErrorCode ierr;
811 
812   PetscFunctionBegin;
813   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
814   ierr = PetscTryMethod(pc,"PCGAMGSetProcEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
815   PetscFunctionReturn(0);
816 }
817 
818 EXTERN_C_BEGIN
819 #undef __FUNCT__
820 #define __FUNCT__ "PCGAMGSetProcEqLim_GAMG"
821 PetscErrorCode PCGAMGSetProcEqLim_GAMG(PC pc, PetscInt n)
822 {
823   PC_MG           *mg = (PC_MG*)pc->data;
824   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
825 
826   PetscFunctionBegin;
827   if(n>0) pc_gamg->min_eq_proc = n;
828   PetscFunctionReturn(0);
829 }
830 EXTERN_C_END
831 
832 #undef __FUNCT__
833 #define __FUNCT__ "PCGAMGSetCoarseEqLim"
834 /*@
835    PCGAMGSetCoarseEqLim - Set max number of equations on coarse grids.
836 
837  Collective on PC
838 
839    Input Parameters:
840 .  pc - the preconditioner context
841 
842 
843    Options Database Key:
844 .  -pc_gamg_coarse_eq_limit
845 
846    Level: intermediate
847 
848    Concepts: Unstructured multrigrid preconditioner
849 
850 .seealso: ()
851  @*/
852 PetscErrorCode PCGAMGSetCoarseEqLim(PC pc, PetscInt n)
853 {
854   PetscErrorCode ierr;
855 
856   PetscFunctionBegin;
857   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
858   ierr = PetscTryMethod(pc,"PCGAMGSetCoarseEqLim_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
859   PetscFunctionReturn(0);
860 }
861 
862 EXTERN_C_BEGIN
863 #undef __FUNCT__
864 #define __FUNCT__ "PCGAMGSetCoarseEqLim_GAMG"
865 PetscErrorCode PCGAMGSetCoarseEqLim_GAMG(PC pc, PetscInt n)
866 {
867   PC_MG           *mg = (PC_MG*)pc->data;
868   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
869 
870   PetscFunctionBegin;
871   if(n>0) pc_gamg->coarse_eq_limit = n;
872   PetscFunctionReturn(0);
873 }
874 EXTERN_C_END
875 
876 #undef __FUNCT__
877 #define __FUNCT__ "PCGAMGSetRepartitioning"
878 /*@
879    PCGAMGSetRepartitioning - Repartition the coarse grids
880 
881    Collective on PC
882 
883    Input Parameters:
884 .  pc - the preconditioner context
885 
886 
887    Options Database Key:
888 .  -pc_gamg_repartition
889 
890    Level: intermediate
891 
892    Concepts: Unstructured multrigrid preconditioner
893 
894 .seealso: ()
895 @*/
896 PetscErrorCode PCGAMGSetRepartitioning(PC pc, PetscBool n)
897 {
898   PetscErrorCode ierr;
899 
900   PetscFunctionBegin;
901   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
902   ierr = PetscTryMethod(pc,"PCGAMGSetRepartitioning_C",(PC,PetscBool),(pc,n));CHKERRQ(ierr);
903   PetscFunctionReturn(0);
904 }
905 
906 EXTERN_C_BEGIN
907 #undef __FUNCT__
908 #define __FUNCT__ "PCGAMGSetRepartitioning_GAMG"
909 PetscErrorCode PCGAMGSetRepartitioning_GAMG(PC pc, PetscBool n)
910 {
911   PC_MG           *mg = (PC_MG*)pc->data;
912   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
913 
914   PetscFunctionBegin;
915   pc_gamg->repart = n;
916   PetscFunctionReturn(0);
917 }
918 EXTERN_C_END
919 
920 #undef __FUNCT__
921 #define __FUNCT__ "PCGAMGSetNlevels"
922 /*@
923    PCGAMGSetNlevels -
924 
925    Not collective on PC
926 
927    Input Parameters:
928 .  pc - the preconditioner context
929 
930 
931    Options Database Key:
932 .  -pc_mg_levels
933 
934    Level: intermediate
935 
936    Concepts: Unstructured multrigrid preconditioner
937 
938 .seealso: ()
939 @*/
940 PetscErrorCode PCGAMGSetNlevels(PC pc, PetscInt n)
941 {
942   PetscErrorCode ierr;
943 
944   PetscFunctionBegin;
945   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
946   ierr = PetscTryMethod(pc,"PCGAMGSetNlevels_C",(PC,PetscInt),(pc,n));CHKERRQ(ierr);
947   PetscFunctionReturn(0);
948 }
949 
950 EXTERN_C_BEGIN
951 #undef __FUNCT__
952 #define __FUNCT__ "PCGAMGSetNlevels_GAMG"
953 PetscErrorCode PCGAMGSetNlevels_GAMG(PC pc, PetscInt n)
954 {
955   PC_MG           *mg = (PC_MG*)pc->data;
956   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
957 
958   PetscFunctionBegin;
959   pc_gamg->Nlevels = n;
960   PetscFunctionReturn(0);
961 }
962 EXTERN_C_END
963 
964 #undef __FUNCT__
965 #define __FUNCT__ "PCGAMGSetThreshold"
966 /*@
967    PCGAMGSetThreshold - Relative threshold to use for dropping edges in aggregation graph
968 
969    Not collective on PC
970 
971    Input Parameters:
972 .  pc - the preconditioner context
973 
974 
975    Options Database Key:
976 .  -pc_gamg_threshold
977 
978    Level: intermediate
979 
980    Concepts: Unstructured multrigrid preconditioner
981 
982 .seealso: ()
983 @*/
984 PetscErrorCode PCGAMGSetThreshold(PC pc, PetscReal n)
985 {
986   PetscErrorCode ierr;
987 
988   PetscFunctionBegin;
989   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
990   ierr = PetscTryMethod(pc,"PCGAMGSetThreshold_C",(PC,PetscReal),(pc,n));CHKERRQ(ierr);
991   PetscFunctionReturn(0);
992 }
993 
994 EXTERN_C_BEGIN
995 #undef __FUNCT__
996 #define __FUNCT__ "PCGAMGSetThreshold_GAMG"
997 PetscErrorCode PCGAMGSetThreshold_GAMG(PC pc, PetscReal n)
998 {
999   PC_MG           *mg = (PC_MG*)pc->data;
1000   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1001 
1002   PetscFunctionBegin;
1003   pc_gamg->threshold = n;
1004   PetscFunctionReturn(0);
1005 }
1006 EXTERN_C_END
1007 
1008 #undef __FUNCT__
1009 #define __FUNCT__ "PCGAMGSetType"
1010 /*@
1011    PCGAMGSetType - Set solution method - calls sub create method
1012 
1013    Collective on PC
1014 
1015    Input Parameters:
1016 .  pc - the preconditioner context
1017 
1018 
1019    Options Database Key:
1020 .  -pc_gamg_type
1021 
1022    Level: intermediate
1023 
1024    Concepts: Unstructured multrigrid preconditioner
1025 
1026 .seealso: ()
1027 @*/
1028 PetscErrorCode PCGAMGSetType( PC pc, const PCGAMGType type )
1029 {
1030   PetscErrorCode ierr;
1031 
1032   PetscFunctionBegin;
1033   PetscValidHeaderSpecific(pc,PC_CLASSID,1);
1034   ierr = PetscTryMethod(pc,"PCGAMGSetType_C",(PC,const PCGAMGType),(pc,type));
1035   CHKERRQ(ierr);
1036   PetscFunctionReturn(0);
1037 }
1038 
1039 EXTERN_C_BEGIN
1040 #undef __FUNCT__
1041 #define __FUNCT__ "PCGAMGSetType_GAMG"
1042 PetscErrorCode PCGAMGSetType_GAMG( PC pc, const PCGAMGType type )
1043 {
1044   PetscErrorCode ierr,(*r)(PC);
1045 
1046   PetscFunctionBegin;
1047   ierr = PetscFListFind(GAMGList,((PetscObject)pc)->comm,type,PETSC_FALSE,(PetscVoidStarFunction)&r);
1048   CHKERRQ(ierr);
1049 
1050   if (!r) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_ARG_UNKNOWN_TYPE,"Unknown GAMG type %s given",type);
1051 
1052   /* call sub create method */
1053   ierr = (*r)(pc); CHKERRQ(ierr);
1054 
1055   PetscFunctionReturn(0);
1056 }
1057 EXTERN_C_END
1058 
1059 #undef __FUNCT__
1060 #define __FUNCT__ "PCSetFromOptions_GAMG"
1061 PetscErrorCode PCSetFromOptions_GAMG( PC pc )
1062 {
1063   PetscErrorCode  ierr;
1064   PC_MG           *mg = (PC_MG*)pc->data;
1065   PC_GAMG         *pc_gamg = (PC_GAMG*)mg->innerctx;
1066   PetscBool        flag;
1067   MPI_Comm         wcomm = ((PetscObject)pc)->comm;
1068 
1069   PetscFunctionBegin;
1070   ierr = PetscOptionsHead("GAMG options"); CHKERRQ(ierr);
1071   {
1072     /* -pc_gamg_verbose */
1073     ierr = PetscOptionsInt("-pc_gamg_verbose","Verbose (debugging) output for PCGAMG",
1074                            "none", pc_gamg->verbose,
1075                            &pc_gamg->verbose, PETSC_NULL );
1076     CHKERRQ(ierr);
1077 
1078     /* -pc_gamg_repartition */
1079     ierr = PetscOptionsBool("-pc_gamg_repartition",
1080                             "Repartion coarse grids (false)",
1081                             "PCGAMGRepartitioning",
1082                             pc_gamg->repart,
1083                             &pc_gamg->repart,
1084                             &flag);
1085     CHKERRQ(ierr);
1086 
1087     /* -pc_gamg_process_eq_limit */
1088     ierr = PetscOptionsInt("-pc_gamg_process_eq_limit",
1089                            "Limit (goal) on number of equations per process on coarse grids",
1090                            "PCGAMGSetProcEqLim",
1091                            pc_gamg->min_eq_proc,
1092                            &pc_gamg->min_eq_proc,
1093                            &flag );
1094     CHKERRQ(ierr);
1095 
1096     /* -pc_gamg_coarse_eq_limit */
1097     ierr = PetscOptionsInt("-pc_gamg_coarse_eq_limit",
1098                            "Limit on number of equations for the coarse grid",
1099                            "PCGAMGSetCoarseEqLim",
1100                            pc_gamg->coarse_eq_limit,
1101                            &pc_gamg->coarse_eq_limit,
1102                            &flag );
1103     CHKERRQ(ierr);
1104 
1105     /* -pc_gamg_threshold */
1106     ierr = PetscOptionsReal("-pc_gamg_threshold",
1107                             "Relative threshold to use for dropping edges in aggregation graph",
1108                             "PCGAMGSetThreshold",
1109                             pc_gamg->threshold,
1110                             &pc_gamg->threshold,
1111                             &flag );
1112     CHKERRQ(ierr);
1113     if(flag && pc_gamg->verbose) PetscPrintf(wcomm,"\t[%d]%s threshold set %e\n",0,__FUNCT__,pc_gamg->threshold);
1114 
1115     ierr = PetscOptionsInt("-pc_mg_levels",
1116                            "Set number of MG levels",
1117                            "PCGAMGSetNlevels",
1118                            pc_gamg->Nlevels,
1119                            &pc_gamg->Nlevels,
1120                            &flag );
1121   }
1122   ierr = PetscOptionsTail();CHKERRQ(ierr);
1123 
1124   PetscFunctionReturn(0);
1125 }
1126 
1127 /* -------------------------------------------------------------------------- */
1128 /*MC
1129      PCCreate_GAMG - Geometric algebraic multigrid (AMG) preconditioning framework.
1130        - This is the entry point to GAMG, registered in pcregis.c
1131 
1132    Options Database Keys:
1133    Multigrid options(inherited)
1134 +  -pc_mg_cycles <1>: 1 for V cycle, 2 for W-cycle (PCMGSetCycleType)
1135 .  -pc_mg_smoothup <1>: Number of post-smoothing steps (PCMGSetNumberSmoothUp)
1136 .  -pc_mg_smoothdown <1>: Number of pre-smoothing steps (PCMGSetNumberSmoothDown)
1137 -  -pc_mg_type <multiplicative>: (one of) additive multiplicative full cascade kascade
1138 
1139   Level: intermediate
1140 
1141   Concepts: multigrid
1142 
1143 .seealso:  PCCreate(), PCSetType(), PCType (for list of available types), PC, PCMGType,
1144            PCMGSetLevels(), PCMGGetLevels(), PCMGSetType(), PCMGSetCycleType(), PCMGSetNumberSmoothDown(),
1145            PCMGSetNumberSmoothUp(), PCMGGetCoarseSolve(), PCMGSetResidual(), PCMGSetInterpolation(),
1146            PCMGSetRestriction(), PCMGGetSmoother(), PCMGGetSmootherUp(), PCMGGetSmootherDown(),
1147            PCMGSetCyclesOnLevel(), PCMGSetRhs(), PCMGSetX(), PCMGSetR()
1148 M*/
1149 EXTERN_C_BEGIN
1150 #undef __FUNCT__
1151 #define __FUNCT__ "PCCreate_GAMG"
1152 PetscErrorCode  PCCreate_GAMG( PC pc )
1153 {
1154   PetscErrorCode  ierr;
1155   PC_GAMG         *pc_gamg;
1156   PC_MG           *mg;
1157   PetscClassId     cookie;
1158 
1159 #if defined PETSC_USE_LOG
1160   static long count = 0;
1161 #endif
1162 
1163   PetscFunctionBegin;
1164   /* PCGAMG is an inherited class of PCMG. Initialize pc as PCMG */
1165   ierr = PCSetType( pc, PCMG );  CHKERRQ(ierr); /* calls PCCreate_MG() and MGCreate_Private() */
1166   ierr = PetscObjectChangeTypeName( (PetscObject)pc, PCGAMG ); CHKERRQ(ierr);
1167 
1168   /* create a supporting struct and attach it to pc */
1169   ierr = PetscNewLog( pc, PC_GAMG, &pc_gamg ); CHKERRQ(ierr);
1170   mg = (PC_MG*)pc->data;
1171   mg->galerkin = 2;             /* Use Galerkin, but it is computed externally */
1172   mg->innerctx = pc_gamg;
1173 
1174   pc_gamg->setup_count = 0;
1175   /* these should be in subctx but repartitioning needs simple arrays */
1176   pc_gamg->data_sz = 0;
1177   pc_gamg->data = 0;
1178 
1179   /* register AMG type */
1180   if( !GAMGList ){
1181     ierr = PetscFListAdd(&GAMGList,GAMGGEO,"PCCreateGAMG_GEO",(void(*)(void))PCCreateGAMG_GEO);CHKERRQ(ierr);
1182     ierr = PetscFListAdd(&GAMGList,GAMGAGG,"PCCreateGAMG_AGG",(void(*)(void))PCCreateGAMG_AGG);CHKERRQ(ierr);
1183   }
1184 
1185   /* overwrite the pointers of PCMG by the functions of base class PCGAMG */
1186   pc->ops->setfromoptions = PCSetFromOptions_GAMG;
1187   pc->ops->setup          = PCSetUp_GAMG;
1188   pc->ops->reset          = PCReset_GAMG;
1189   pc->ops->destroy        = PCDestroy_GAMG;
1190 
1191   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1192 					    "PCGAMGSetProcEqLim_C",
1193 					    "PCGAMGSetProcEqLim_GAMG",
1194 					    PCGAMGSetProcEqLim_GAMG);
1195   CHKERRQ(ierr);
1196 
1197   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1198 					    "PCGAMGSetCoarseEqLim_C",
1199 					    "PCGAMGSetCoarseEqLim_GAMG",
1200 					    PCGAMGSetCoarseEqLim_GAMG);
1201   CHKERRQ(ierr);
1202 
1203   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1204 					    "PCGAMGSetRepartitioning_C",
1205 					    "PCGAMGSetRepartitioning_GAMG",
1206 					    PCGAMGSetRepartitioning_GAMG);
1207   CHKERRQ(ierr);
1208 
1209   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1210 					    "PCGAMGSetThreshold_C",
1211 					    "PCGAMGSetThreshold_GAMG",
1212 					    PCGAMGSetThreshold_GAMG);
1213   CHKERRQ(ierr);
1214 
1215   ierr = PetscObjectComposeFunctionDynamic( (PetscObject)pc,
1216 					    "PCGAMGSetType_C",
1217 					    "PCGAMGSetType_GAMG",
1218 					    PCGAMGSetType_GAMG);
1219   CHKERRQ(ierr);
1220 
1221   pc_gamg->repart = PETSC_FALSE;
1222   pc_gamg->min_eq_proc = 100;
1223   pc_gamg->coarse_eq_limit = 800;
1224   pc_gamg->threshold = 0.05;
1225   pc_gamg->Nlevels = GAMG_MAXLEVELS;
1226   pc_gamg->verbose = 0;
1227   pc_gamg->emax_id = -1;
1228   pc_gamg->col_bs_id = -1;
1229 
1230   /* instantiate derived type */
1231   ierr = PetscOptionsHead("GAMG options"); CHKERRQ(ierr);
1232   {
1233     char tname[256] = GAMGAGG;
1234     ierr = PetscOptionsList("-pc_gamg_type","Type of GAMG method","PCGAMGSetType",
1235                             GAMGList, tname, tname, sizeof(tname), PETSC_NULL );
1236     CHKERRQ(ierr);
1237     ierr = PCGAMGSetType( pc, tname ); CHKERRQ(ierr);
1238   }
1239   ierr = PetscOptionsTail();CHKERRQ(ierr);
1240 
1241 #if defined PETSC_USE_LOG
1242   if( count++ == 0 ) {
1243     PetscClassIdRegister("GAMG Setup",&cookie);
1244     PetscLogEventRegister("GAMG: createProl", cookie, &gamg_setup_events[SET1]);
1245     PetscLogEventRegister("  Graph", cookie, &gamg_setup_events[GRAPH]);
1246     /* PetscLogEventRegister("    G.Mat", cookie, &gamg_setup_events[GRAPH_MAT]); */
1247     /* PetscLogEventRegister("    G.Filter", cookie, &gamg_setup_events[GRAPH_FILTER]); */
1248     /* PetscLogEventRegister("    G.Square", cookie, &gamg_setup_events[GRAPH_SQR]); */
1249     PetscLogEventRegister("  MIS/Agg", cookie, &gamg_setup_events[SET4]);
1250     PetscLogEventRegister("  geo: growSupp", cookie, &gamg_setup_events[SET5]);
1251     PetscLogEventRegister("  geo: triangle", cookie, &gamg_setup_events[SET6]);
1252     PetscLogEventRegister("    search&set", cookie, &gamg_setup_events[FIND_V]);
1253     PetscLogEventRegister("  SA: colect data", cookie, &gamg_setup_events[SET7]);
1254     PetscLogEventRegister("  SA: frmProl0", cookie, &gamg_setup_events[SET8]);
1255     PetscLogEventRegister("  SA: smooth", cookie, &gamg_setup_events[SET9]);
1256     PetscLogEventRegister("GAMG: partLevel", cookie, &gamg_setup_events[SET2]);
1257     PetscLogEventRegister("  repartition", cookie, &gamg_setup_events[SET12]);
1258     PetscLogEventRegister("  Invert-Sort", cookie, &gamg_setup_events[SET13]);
1259     PetscLogEventRegister("  Move A", cookie, &gamg_setup_events[SET14]);
1260     PetscLogEventRegister("  Move P", cookie, &gamg_setup_events[SET15]);
1261 
1262     /* PetscLogEventRegister(" PL move data", cookie, &gamg_setup_events[SET13]); */
1263     /* PetscLogEventRegister("GAMG: fix", cookie, &gamg_setup_events[SET10]); */
1264     /* PetscLogEventRegister("GAMG: set levels", cookie, &gamg_setup_events[SET11]); */
1265     /* create timer stages */
1266 #if defined GAMG_STAGES
1267     {
1268       char str[32];
1269       sprintf(str,"MG Level %d (finest)",0);
1270       PetscLogStageRegister(str, &gamg_stages[0]);
1271       PetscInt lidx;
1272       for (lidx=1;lidx<9;lidx++){
1273 	sprintf(str,"MG Level %d",lidx);
1274 	PetscLogStageRegister(str, &gamg_stages[lidx]);
1275       }
1276     }
1277 #endif
1278   }
1279 #endif
1280   PetscFunctionReturn(0);
1281 }
1282 EXTERN_C_END
1283