xref: /petsc/src/ksp/pc/impls/bddc/bddcschurs.c (revision 65d8bf0a82b01a6bbcb5d0fd403f7ff82932c095)
1 #include <../src/ksp/pc/impls/bddc/bddc.h>
2 #include <../src/ksp/pc/impls/bddc/bddcprivate.h>
3 
4 PETSC_STATIC_INLINE PetscErrorCode PCBDDCAdjGetNextLayer_Private(PetscInt*,PetscInt,PetscBT,PetscInt*,PetscInt*,PetscInt*);
5 static PetscErrorCode PCBDDCComputeExplicitSchur(Mat M, Mat *S);
6 
7 #undef __FUNCT__
8 #define __FUNCT__ "PCBDDCComputeExplicitSchur"
9 static PetscErrorCode PCBDDCComputeExplicitSchur(Mat M, Mat *S)
10 {
11   Mat            B, C, D, Bd, Cd, AinvBd;
12   KSP            ksp;
13   PC             pc;
14   PetscBool      isLU, isILU, isCHOL, Bdense, Cdense;
15   PetscReal      fill = 2.0;
16   PetscMPIInt    size;
17   PetscErrorCode ierr;
18 
19   PetscFunctionBegin;
20   ierr = MPI_Comm_size(PetscObjectComm((PetscObject)M),&size);CHKERRQ(ierr);
21   if (size != 1) {
22     SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Not for parallel matrices");
23   }
24   ierr = MatSchurComplementGetSubMatrices(M, NULL, NULL, &B, &C, &D);CHKERRQ(ierr);
25   ierr = MatSchurComplementGetKSP(M, &ksp);CHKERRQ(ierr);
26   ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
27   ierr = PetscObjectTypeCompare((PetscObject) pc, PCLU, &isLU);CHKERRQ(ierr);
28   ierr = PetscObjectTypeCompare((PetscObject) pc, PCILU, &isILU);CHKERRQ(ierr);
29   ierr = PetscObjectTypeCompare((PetscObject) pc, PCCHOLESKY, &isCHOL);CHKERRQ(ierr);
30   ierr = PetscObjectTypeCompare((PetscObject) B, MATSEQDENSE, &Bdense);CHKERRQ(ierr);
31   ierr = PetscObjectTypeCompare((PetscObject) C, MATSEQDENSE, &Cdense);CHKERRQ(ierr);
32   if (!Bdense) {
33     ierr = MatConvert(B, MATSEQDENSE, MAT_INITIAL_MATRIX, &Bd);CHKERRQ(ierr);
34   } else {
35     Bd = B;
36   }
37 
38   if (isLU || isILU || isCHOL) {
39     Mat fact;
40 
41     ierr = KSPSetUp(ksp);CHKERRQ(ierr);
42     ierr = PCFactorGetMatrix(pc, &fact);CHKERRQ(ierr);
43     ierr = MatDuplicate(Bd, MAT_DO_NOT_COPY_VALUES, &AinvBd);CHKERRQ(ierr);
44     ierr = MatMatSolve(fact, Bd, AinvBd);CHKERRQ(ierr);
45   } else {
46     Mat Ainvd;
47 
48     ierr = PCComputeExplicitOperator(pc, &Ainvd);CHKERRQ(ierr);
49     ierr = MatMatMult(Ainvd, Bd, MAT_INITIAL_MATRIX, fill, &AinvBd);CHKERRQ(ierr);
50     ierr = MatDestroy(&Ainvd);CHKERRQ(ierr);
51   }
52   if (!Bdense) {
53     ierr = MatDestroy(&Bd);CHKERRQ(ierr);
54   }
55   if (!Cdense) {
56     ierr = MatConvert(C, MATSEQDENSE, MAT_INITIAL_MATRIX, &Cd);CHKERRQ(ierr);
57   } else {
58     Cd = C;
59   }
60 
61   ierr = MatMatMult(Cd, AinvBd, MAT_INITIAL_MATRIX, fill, S);CHKERRQ(ierr);
62   ierr = MatDestroy(&AinvBd);CHKERRQ(ierr);
63   if (!Cdense) {
64     ierr = MatDestroy(&Cd);CHKERRQ(ierr);
65   }
66 
67   if (D) {
68     Mat       Dd;
69     PetscBool Ddense;
70 
71     ierr = PetscObjectTypeCompare((PetscObject)D,MATSEQDENSE,&Ddense);CHKERRQ(ierr);
72     if (!Ddense) {
73       ierr = MatConvert(D, MATSEQDENSE, MAT_INITIAL_MATRIX, &Dd);CHKERRQ(ierr);
74     } else {
75       Dd = D;
76     }
77     ierr = MatAYPX(*S,-1.0,Dd,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
78     if (!Ddense) {
79       ierr = MatDestroy(&Dd);CHKERRQ(ierr);
80     }
81   } else {
82     ierr = MatScale(*S,-1.0);CHKERRQ(ierr);
83   }
84   PetscFunctionReturn(0);
85 }
86 
87 #undef __FUNCT__
88 #define __FUNCT__ "PCBDDCSubSchursSetUp"
89 PetscErrorCode PCBDDCSubSchursSetUp(PCBDDCSubSchurs sub_schurs, PetscInt xadj[], PetscInt adjncy[], PetscInt nlayers)
90 {
91   Mat                    A_II,A_IB,A_BI,A_BB;
92   Mat                    AE_II,*AE_IE,*AE_EI,*AE_EE;
93   Mat                    S_all,global_schur_subsets,work_mat;
94   ISLocalToGlobalMapping l2gmap_subsets;
95   IS                     is_I,*is_subset_B,temp_is;
96   PetscInt               *nnz,*all_local_idx_G,*all_local_idx_B,*all_local_idx_N;
97   PetscInt               i,subset_size,max_subset_size;
98   PetscInt               extra,local_size,global_size;
99   PetscErrorCode         ierr;
100 
101   PetscFunctionBegin;
102 
103   /* allocate space for schur complements */
104   ierr = PetscMalloc4(sub_schurs->n_subs,&sub_schurs->is_AEj_B,
105                       sub_schurs->n_subs,&sub_schurs->S_Ej,
106                       sub_schurs->n_subs,&sub_schurs->work1,
107                       sub_schurs->n_subs,&sub_schurs->work2);CHKERRQ(ierr);
108 
109   /* get Schur complement matrices */
110   if (!sub_schurs->use_mumps) {
111     ierr = MatSchurComplementGetSubMatrices(sub_schurs->S,&A_II,NULL,&A_IB,&A_BI,&A_BB);CHKERRQ(ierr);
112     ierr = PetscMalloc4(sub_schurs->n_subs,&is_subset_B,
113                         sub_schurs->n_subs,&AE_IE,
114                         sub_schurs->n_subs,&AE_EI,
115                         sub_schurs->n_subs,&AE_EE);CHKERRQ(ierr);
116   }
117 
118   /* determine interior problems */
119   if (nlayers >= 0 && xadj != NULL && adjncy != NULL) { /* Interior problems can be different from the original one */
120     PetscBT                touched;
121     const PetscInt*        idx_B;
122     PetscInt               n_I,n_B,n_local_dofs,n_prev_added,j,layer,*local_numbering;
123 
124     /* get sizes */
125     ierr = ISGetLocalSize(sub_schurs->is_I,&n_I);CHKERRQ(ierr);
126     ierr = ISGetLocalSize(sub_schurs->is_B,&n_B);CHKERRQ(ierr);
127 
128     ierr = PetscMalloc1(n_I+n_B,&local_numbering);CHKERRQ(ierr);
129     ierr = PetscBTCreate(n_I+n_B,&touched);CHKERRQ(ierr);
130     ierr = PetscBTMemzero(n_I+n_B,touched);CHKERRQ(ierr);
131 
132     /* all boundary dofs must be skipped when adding layers */
133     ierr = ISGetIndices(sub_schurs->is_B,&idx_B);CHKERRQ(ierr);
134     for (j=0;j<n_B;j++) {
135       ierr = PetscBTSet(touched,idx_B[j]);CHKERRQ(ierr);
136     }
137     ierr = PetscMemcpy(local_numbering,idx_B,n_B*sizeof(PetscInt));CHKERRQ(ierr);
138     ierr = ISRestoreIndices(sub_schurs->is_B,&idx_B);CHKERRQ(ierr);
139 
140     /* add prescribed number of layers of dofs */
141     n_local_dofs = n_B;
142     n_prev_added = n_B;
143     for (layer=0;layer<nlayers;layer++) {
144       PetscInt n_added;
145       if (n_local_dofs == n_I+n_B) break;
146       if (n_local_dofs > n_I+n_B) {
147         SETERRQ3(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Error querying layer %d. Out of bound access (%d > %d)",layer,n_local_dofs,n_I+n_B);
148       }
149       ierr = PCBDDCAdjGetNextLayer_Private(local_numbering+n_local_dofs,n_prev_added,touched,xadj,adjncy,&n_added);CHKERRQ(ierr);
150       n_prev_added = n_added;
151       n_local_dofs += n_added;
152       if (!n_added) break;
153     }
154     ierr = PetscBTDestroy(&touched);CHKERRQ(ierr);
155 
156     /* IS for I layer dofs in original numbering */
157     ierr = ISCreateGeneral(PetscObjectComm((PetscObject)sub_schurs->is_I),n_local_dofs-n_B,local_numbering+n_B,PETSC_COPY_VALUES,&sub_schurs->is_I_layer);CHKERRQ(ierr);
158     ierr = PetscFree(local_numbering);CHKERRQ(ierr);
159     ierr = ISSort(sub_schurs->is_I_layer);CHKERRQ(ierr);
160     /* IS for I layer dofs in I numbering */
161     if (!sub_schurs->use_mumps) {
162       ISLocalToGlobalMapping ItoNmap;
163       ierr = ISLocalToGlobalMappingCreateIS(sub_schurs->is_I,&ItoNmap);CHKERRQ(ierr);
164       ierr = ISGlobalToLocalMappingApplyIS(ItoNmap,IS_GTOLM_DROP,sub_schurs->is_I_layer,&is_I);CHKERRQ(ierr);
165       ierr = ISLocalToGlobalMappingDestroy(&ItoNmap);CHKERRQ(ierr);
166 
167       /* II block */
168       ierr = MatGetSubMatrix(A_II,is_I,is_I,MAT_INITIAL_MATRIX,&AE_II);CHKERRQ(ierr);
169     }
170   } else {
171     PetscInt n_I;
172 
173     /* IS for I dofs in original numbering */
174     ierr = PetscObjectReference((PetscObject)sub_schurs->is_I);CHKERRQ(ierr);
175     sub_schurs->is_I_layer = sub_schurs->is_I;
176 
177     /* IS for I dofs in I numbering (strided 1) */
178     if (!sub_schurs->use_mumps) {
179       ierr = ISGetSize(sub_schurs->is_I,&n_I);CHKERRQ(ierr);
180       ierr = ISCreateStride(PetscObjectComm((PetscObject)sub_schurs->is_I),n_I,0,1,&is_I);CHKERRQ(ierr);
181 
182       /* II block is the same */
183       ierr = PetscObjectReference((PetscObject)A_II);CHKERRQ(ierr);
184       AE_II = A_II;
185     }
186   }
187 
188   for (i=0;i<sub_schurs->n_subs;i++) {
189     ierr = ISDuplicate(sub_schurs->is_subs[i],&sub_schurs->is_AEj_B[i]);CHKERRQ(ierr);
190     ierr = ISSort(sub_schurs->is_AEj_B[i]);CHKERRQ(ierr);
191   }
192 
193   /* Get info on subset sizes and sum of all subsets sizes */
194   max_subset_size = 0;
195   local_size = 0;
196   for (i=0;i<sub_schurs->n_subs_seq;i++) {
197     PetscInt j = sub_schurs->index_sequential[i];
198     ierr = ISGetLocalSize(sub_schurs->is_AEj_B[j],&subset_size);CHKERRQ(ierr);
199     max_subset_size = PetscMax(subset_size,max_subset_size);
200     local_size += subset_size;
201   }
202 
203   /* Work arrays for local indices */
204   ierr = PetscMalloc1(local_size,&all_local_idx_B);CHKERRQ(ierr);
205   extra = 0;
206   if (sub_schurs->use_mumps) {
207     ierr = ISGetLocalSize(sub_schurs->is_I_layer,&extra);CHKERRQ(ierr);
208   }
209   ierr = PetscMalloc1(local_size+extra,&all_local_idx_N);CHKERRQ(ierr);
210   if (extra) {
211     const PetscInt *idxs;
212     ierr = ISGetIndices(sub_schurs->is_I_layer,&idxs);CHKERRQ(ierr);
213     ierr = PetscMemcpy(all_local_idx_N,idxs,extra*sizeof(PetscInt));CHKERRQ(ierr);
214     ierr = ISRestoreIndices(sub_schurs->is_I_layer,&idxs);CHKERRQ(ierr);
215   }
216   ierr = PetscMalloc1(local_size,&nnz);CHKERRQ(ierr);
217 
218   /* Get local indices in local numbering */
219   local_size = 0;
220   for (i=0;i<sub_schurs->n_subs_seq;i++) {
221     PetscInt j;
222     const    PetscInt *idxs;
223 
224     PetscInt local_problem_index = sub_schurs->index_sequential[i];
225     ierr = ISGetLocalSize(sub_schurs->is_AEj_B[local_problem_index],&subset_size);CHKERRQ(ierr);
226     ierr = ISGetIndices(sub_schurs->is_AEj_B[local_problem_index],&idxs);CHKERRQ(ierr);
227     /* subset indices in local numbering */
228     ierr = PetscMemcpy(all_local_idx_N+local_size+extra,idxs,subset_size*sizeof(PetscInt));CHKERRQ(ierr);
229     ierr = ISRestoreIndices(sub_schurs->is_AEj_B[local_problem_index],&idxs);CHKERRQ(ierr);
230     for (j=0;j<subset_size;j++) nnz[local_size+j] = subset_size;
231     local_size += subset_size;
232   }
233 
234   S_all = NULL;
235   if (!sub_schurs->use_mumps) {
236     /* subsets in original and boundary numbering */
237     for (i=0;i<sub_schurs->n_subs;i++) {
238       ierr = ISGlobalToLocalMappingApplyIS(sub_schurs->BtoNmap,IS_GTOLM_DROP,sub_schurs->is_AEj_B[i],&is_subset_B[i]);CHKERRQ(ierr);
239     }
240 
241     /* EE block */
242     for (i=0;i<sub_schurs->n_subs;i++) {
243       ierr = MatGetSubMatrix(A_BB,is_subset_B[i],is_subset_B[i],MAT_INITIAL_MATRIX,&AE_EE[i]);CHKERRQ(ierr);
244     }
245     /* IE block */
246     for (i=0;i<sub_schurs->n_subs;i++) {
247       ierr = MatGetSubMatrix(A_IB,is_I,is_subset_B[i],MAT_INITIAL_MATRIX,&AE_IE[i]);CHKERRQ(ierr);
248     }
249     /* EI block */
250     for (i=0;i<sub_schurs->n_subs;i++) {
251       ierr = MatGetSubMatrix(A_BI,is_subset_B[i],is_I,MAT_INITIAL_MATRIX,&AE_EI[i]);CHKERRQ(ierr);
252     }
253 
254     /* setup Schur complements on subset */
255     for (i=0;i<sub_schurs->n_subs;i++) {
256       ierr = MatCreateSchurComplement(AE_II,AE_II,AE_IE[i],AE_EI[i],AE_EE[i],&sub_schurs->S_Ej[i]);CHKERRQ(ierr);
257       if (AE_II == A_II) { /* we can reuse the same ksp */
258         KSP ksp;
259         ierr = MatSchurComplementGetKSP(sub_schurs->S,&ksp);CHKERRQ(ierr);
260         ierr = MatSchurComplementSetKSP(sub_schurs->S_Ej[i],ksp);CHKERRQ(ierr);
261       } else { /* build new ksp object which inherits ksp and pc types from the original one */
262         KSP      origksp,schurksp;
263         PC       origpc,schurpc;
264         KSPType  ksp_type;
265         PCType   pc_type;
266         PetscInt n_internal;
267 
268         ierr = MatSchurComplementGetKSP(sub_schurs->S,&origksp);CHKERRQ(ierr);
269         ierr = MatSchurComplementGetKSP(sub_schurs->S_Ej[i],&schurksp);CHKERRQ(ierr);
270         ierr = KSPGetType(origksp,&ksp_type);CHKERRQ(ierr);
271         ierr = KSPSetType(schurksp,ksp_type);CHKERRQ(ierr);
272         ierr = KSPGetPC(schurksp,&schurpc);CHKERRQ(ierr);
273         ierr = KSPGetPC(origksp,&origpc);CHKERRQ(ierr);
274         ierr = PCGetType(origpc,&pc_type);CHKERRQ(ierr);
275         ierr = PCSetType(schurpc,pc_type);CHKERRQ(ierr);
276         ierr = ISGetSize(is_I,&n_internal);CHKERRQ(ierr);
277         if (n_internal) { /* UMFPACK gives error with 0 sized problems */
278           MatSolverPackage solver=NULL;
279           ierr = PCFactorGetMatSolverPackage(origpc,(const MatSolverPackage*)&solver);CHKERRQ(ierr);
280           if (solver) {
281             ierr = PCFactorSetMatSolverPackage(schurpc,solver);CHKERRQ(ierr);
282           }
283         }
284         ierr = KSPSetUp(schurksp);CHKERRQ(ierr);
285       }
286     }
287     /* free */
288     ierr = ISDestroy(&is_I);CHKERRQ(ierr);
289     ierr = MatDestroy(&AE_II);CHKERRQ(ierr);
290     for (i=0;i<sub_schurs->n_subs;i++) {
291       ierr = MatDestroy(&AE_EE[i]);CHKERRQ(ierr);
292       ierr = MatDestroy(&AE_IE[i]);CHKERRQ(ierr);
293       ierr = MatDestroy(&AE_EI[i]);CHKERRQ(ierr);
294       ierr = ISDestroy(&is_subset_B[i]);CHKERRQ(ierr);
295     }
296     ierr = PetscFree4(is_subset_B,AE_IE,AE_EI,AE_EE);CHKERRQ(ierr);
297 #if defined(PETSC_HAVE_MUMPS)
298   } else {
299     Mat           A,F;
300     IS            is_A_all;
301     PetscBool     is_symmetric;
302     PetscInt      *idxs_schur,n_I;
303 
304     /* get working mat */
305     ierr = ISGetLocalSize(sub_schurs->is_I_layer,&n_I);CHKERRQ(ierr);
306     ierr = ISCreateGeneral(PETSC_COMM_SELF,local_size+n_I,all_local_idx_N,PETSC_COPY_VALUES,&is_A_all);CHKERRQ(ierr);
307     ierr = MatGetSubMatrixUnsorted(sub_schurs->A,is_A_all,is_A_all,&A);CHKERRQ(ierr);
308     ierr = ISDestroy(&is_A_all);CHKERRQ(ierr);
309 
310     ierr = MatIsSymmetric(sub_schurs->A,0.0,&is_symmetric);CHKERRQ(ierr);
311     if (is_symmetric) {
312       ierr = MatGetFactor(A,MATSOLVERMUMPS,MAT_FACTOR_CHOLESKY,&F);CHKERRQ(ierr);
313     } else {
314       ierr = MatGetFactor(A,MATSOLVERMUMPS,MAT_FACTOR_LU,&F);CHKERRQ(ierr);
315     }
316 
317     /* subsets ordered last */
318     ierr = PetscMalloc1(local_size,&idxs_schur);CHKERRQ(ierr);
319     for (i=0;i<local_size;i++) {
320       idxs_schur[i] = n_I+i+1;
321     }
322     ierr = MatMumpsSetSchurIndices(F,local_size,idxs_schur);CHKERRQ(ierr);
323     ierr = PetscFree(idxs_schur);CHKERRQ(ierr);
324 
325     /* factorization step */
326     if (is_symmetric) {
327       ierr = MatCholeskyFactorSymbolic(F,A,NULL,NULL);CHKERRQ(ierr);
328       ierr = MatCholeskyFactorNumeric(F,A,NULL);CHKERRQ(ierr);
329     } else {
330       ierr = MatLUFactorSymbolic(F,A,NULL,NULL,NULL);CHKERRQ(ierr);
331       ierr = MatLUFactorNumeric(F,A,NULL);CHKERRQ(ierr);
332     }
333 
334     /* get explicit Schur Complement computed during numeric factorization */
335     ierr = MatMumpsGetSchurComplement(F,&S_all);CHKERRQ(ierr);
336 
337     /* free workspace */
338     ierr = MatDestroy(&A);CHKERRQ(ierr);
339     ierr = MatDestroy(&F);CHKERRQ(ierr);
340 
341 #endif
342   }
343 
344   /* TODO: just for compatibility with the previous version, needs to be fixed */
345   for (i=0;i<sub_schurs->n_subs_par;i++) {
346     PetscInt j = sub_schurs->index_parallel[i];
347     ierr = MatCreateVecs(sub_schurs->S_Ej[j],&sub_schurs->work1[j],&sub_schurs->work2[j]);CHKERRQ(ierr);
348   }
349   for (i=0;i<sub_schurs->n_subs_seq;i++) {
350      sub_schurs->work1[sub_schurs->index_sequential[i]] = 0;
351      sub_schurs->work2[sub_schurs->index_sequential[i]] = 0;
352   }
353 
354   if (!sub_schurs->n_subs_seq_g) {
355     sub_schurs->S_Ej_all = 0;
356     sub_schurs->sum_S_Ej_all = 0;
357     sub_schurs->is_Ej_all = 0;
358     PetscFunctionReturn(0);
359   }
360 
361   /* subset indices in local boundary numbering */
362   ierr = ISGlobalToLocalMappingApply(sub_schurs->BtoNmap,IS_GTOLM_DROP,local_size,all_local_idx_N+extra,&subset_size,all_local_idx_B);CHKERRQ(ierr);
363   if (subset_size != local_size) {
364     SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Error in sub_schurs serial (BtoNmap)! %d != %d\n",subset_size,local_size);
365   }
366   ierr = ISCreateGeneral(PETSC_COMM_SELF,local_size,all_local_idx_B,PETSC_OWN_POINTER,&sub_schurs->is_Ej_all);CHKERRQ(ierr);
367 
368   /* Local matrix of all local Schur on subsets transposed */
369   ierr = MatCreate(PETSC_COMM_SELF,&sub_schurs->S_Ej_all);CHKERRQ(ierr);
370   ierr = MatSetSizes(sub_schurs->S_Ej_all,PETSC_DECIDE,PETSC_DECIDE,local_size,local_size);CHKERRQ(ierr);
371   ierr = MatSetType(sub_schurs->S_Ej_all,MATAIJ);CHKERRQ(ierr);
372   ierr = MatSeqAIJSetPreallocation(sub_schurs->S_Ej_all,0,nnz);CHKERRQ(ierr);
373   ierr = PetscFree(nnz);CHKERRQ(ierr);
374 
375   if (!sub_schurs->use_mumps) {
376     PetscScalar *fill_vals;
377     PetscInt    *dummy_idx;
378 
379     /* Work arrays */
380     ierr = PetscMalloc1(max_subset_size,&dummy_idx);CHKERRQ(ierr);
381 
382     /* Loop on local problems end compute Schur complements explicitly */
383     local_size = 0;
384     for (i=0;i<sub_schurs->n_subs_seq;i++) {
385       Mat       S_Ej_expl;
386       PetscInt  j,lpi = sub_schurs->index_sequential[i];
387       PetscBool Sdense;
388 
389       ierr = PCBDDCComputeExplicitSchur(sub_schurs->S_Ej[lpi],&S_Ej_expl);CHKERRQ(ierr);
390       ierr = ISGetLocalSize(sub_schurs->is_AEj_B[lpi],&subset_size);CHKERRQ(ierr);
391       ierr = PetscObjectTypeCompare((PetscObject)S_Ej_expl,MATSEQDENSE,&Sdense);CHKERRQ(ierr);
392       if (Sdense) {
393         for (j=0;j<subset_size;j++) {
394           dummy_idx[j]=local_size+j;
395         }
396         ierr = MatDenseGetArray(S_Ej_expl,&fill_vals);CHKERRQ(ierr);
397         ierr = MatSetValues(sub_schurs->S_Ej_all,subset_size,dummy_idx,subset_size,dummy_idx,fill_vals,INSERT_VALUES);CHKERRQ(ierr);
398         ierr = MatDenseRestoreArray(S_Ej_expl,&fill_vals);CHKERRQ(ierr);
399       } else {
400         SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Not yet implemented for sparse matrices");
401       }
402       local_size += subset_size;
403       ierr = MatDestroy(&sub_schurs->S_Ej[lpi]);CHKERRQ(ierr);
404       sub_schurs->S_Ej[lpi] = S_Ej_expl;
405     }
406     ierr = PetscFree(dummy_idx);CHKERRQ(ierr);
407   } else {
408     PetscInt  *dummy_idx,n_all;
409     PetscBool is_symmetric,compute_Stilda=PETSC_TRUE;
410 
411     /* Work arrays */
412     ierr = PetscMalloc1(max_subset_size,&dummy_idx);CHKERRQ(ierr);
413 
414     /* Work arrays */
415     ierr = MatGetSize(S_all,&n_all,NULL);CHKERRQ(ierr);
416     local_size = 0;
417     ierr = MatIsSymmetric(sub_schurs->A,0.0,&is_symmetric);CHKERRQ(ierr);
418     for (i=0;i<sub_schurs->n_subs;i++) {
419       Mat S_EE;
420       IS  is_E;
421       PetscScalar *vals;
422       PetscInt j;
423 
424       ierr = ISGetLocalSize(sub_schurs->is_AEj_B[i],&subset_size);CHKERRQ(ierr);
425       ierr = ISCreateStride(PetscObjectComm((PetscObject)sub_schurs->is_I),subset_size,local_size,1,&is_E);CHKERRQ(ierr);
426       ierr = MatGetSubMatrix(S_all,is_E,is_E,MAT_INITIAL_MATRIX,&S_EE);CHKERRQ(ierr);
427       sub_schurs->S_Ej[i] = S_EE;
428       if (compute_Stilda) {
429         Mat Stilda;
430         if (sub_schurs->n_subs == 1) {
431           ierr = PetscObjectReference((PetscObject)sub_schurs->S_Ej[i]);CHKERRQ(ierr);
432           Stilda = sub_schurs->S_Ej[i];
433         } else {
434           KSP ksp;
435           PC  pc;
436           Mat S_EF,S_FE,S_FF,Stilda_impl;
437           IS  is_F;
438 
439           ierr = ISComplement(is_E,0,n_all,&is_F);CHKERRQ(ierr);
440           ierr = MatGetSubMatrix(S_all,is_E,is_F,MAT_INITIAL_MATRIX,&S_EF);CHKERRQ(ierr);
441           ierr = MatGetSubMatrix(S_all,is_F,is_F,MAT_INITIAL_MATRIX,&S_FF);CHKERRQ(ierr);
442           ierr = MatGetSubMatrix(S_all,is_F,is_E,MAT_INITIAL_MATRIX,&S_FE);CHKERRQ(ierr);
443           ierr = MatCreateSchurComplement(S_FF,S_FF,S_FE,S_EF,S_EE,&Stilda_impl);CHKERRQ(ierr);
444           ierr = MatSchurComplementGetKSP(Stilda_impl,&ksp);CHKERRQ(ierr);
445           ierr = KSPSetType(ksp,KSPPREONLY);CHKERRQ(ierr);
446           ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr);
447           if (is_symmetric) {
448             ierr = PCSetType(pc,PCCHOLESKY);CHKERRQ(ierr);
449           } else {
450             ierr = PCSetType(pc,PCLU);CHKERRQ(ierr);
451           }
452           ierr = PCFactorSetUseInPlace(pc,PETSC_TRUE);CHKERRQ(ierr);
453           ierr = KSPSetUp(ksp);CHKERRQ(ierr);
454           ierr = PCBDDCComputeExplicitSchur(Stilda_impl,&Stilda);CHKERRQ(ierr);
455           ierr = MatDestroy(&S_FF);CHKERRQ(ierr);
456           ierr = MatDestroy(&S_FE);CHKERRQ(ierr);
457           ierr = MatDestroy(&S_EF);CHKERRQ(ierr);
458           ierr = MatDestroy(&Stilda_impl);CHKERRQ(ierr);
459           ierr = ISDestroy(&is_F);CHKERRQ(ierr);
460         }
461         ierr = MatDestroy(&Stilda);CHKERRQ(ierr);
462       }
463 
464       for (j=0;j<subset_size;j++) {
465         dummy_idx[j]=local_size+j;
466       }
467       ierr = MatDenseGetArray(S_EE,&vals);CHKERRQ(ierr);
468       ierr = MatSetValues(sub_schurs->S_Ej_all,subset_size,dummy_idx,subset_size,dummy_idx,vals,INSERT_VALUES);CHKERRQ(ierr);
469       ierr = MatDenseRestoreArray(S_EE,&vals);CHKERRQ(ierr);
470       ierr = ISDestroy(&is_E);CHKERRQ(ierr);
471       local_size += subset_size;
472     }
473     ierr = PetscFree(dummy_idx);CHKERRQ(ierr);
474   }
475   ierr = MatAssemblyBegin(sub_schurs->S_Ej_all,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
476   ierr = MatAssemblyEnd(sub_schurs->S_Ej_all,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
477 
478   /* Global matrix of all assembled Schur on subsets */
479   ierr = PCBDDCSubsetNumbering(PetscObjectComm((PetscObject)sub_schurs->l2gmap),sub_schurs->l2gmap,local_size,all_local_idx_N+extra,PETSC_NULL,&global_size,&all_local_idx_G);CHKERRQ(ierr);
480   ierr = ISLocalToGlobalMappingCreate(PetscObjectComm((PetscObject)sub_schurs->l2gmap),1,local_size,all_local_idx_G,PETSC_COPY_VALUES,&l2gmap_subsets);CHKERRQ(ierr);
481   ierr = MatCreateIS(PetscObjectComm((PetscObject)sub_schurs->l2gmap),1,PETSC_DECIDE,PETSC_DECIDE,global_size,global_size,l2gmap_subsets,&work_mat);CHKERRQ(ierr);
482   ierr = ISLocalToGlobalMappingDestroy(&l2gmap_subsets);CHKERRQ(ierr);
483   ierr = MatISSetLocalMat(work_mat,sub_schurs->S_Ej_all);CHKERRQ(ierr);
484   ierr = MatISGetMPIXAIJ(work_mat,MAT_INITIAL_MATRIX,&global_schur_subsets);CHKERRQ(ierr);
485 
486   /* Get local part of (\sum_j S_Ej) */
487   ierr = PetscFree(all_local_idx_N);CHKERRQ(ierr);
488   ierr = ISCreateGeneral(PetscObjectComm((PetscObject)sub_schurs->l2gmap),local_size,all_local_idx_G,PETSC_OWN_POINTER,&temp_is);CHKERRQ(ierr);
489   ierr = MatGetSubMatrixUnsorted(global_schur_subsets,temp_is,temp_is,&sub_schurs->sum_S_Ej_all);CHKERRQ(ierr);
490   ierr = MatDestroy(&global_schur_subsets);CHKERRQ(ierr);
491 
492   /* Computation of Stildas */
493   if (S_all) {
494     PetscInt    n_all;
495     PetscScalar *vals;
496 
497     /* Work arrays */
498     ierr = MatGetSize(S_all,&n_all,NULL);CHKERRQ(ierr);
499     ierr = MatDenseGetArray(S_all,&vals);CHKERRQ(ierr);
500     ierr = MatDenseRestoreArray(S_all,&vals);CHKERRQ(ierr);
501   }
502 
503   ierr = MatDestroy(&S_all);CHKERRQ(ierr);
504   ierr = MatDestroy(&work_mat);CHKERRQ(ierr);
505   ierr = ISDestroy(&temp_is);CHKERRQ(ierr);
506   PetscFunctionReturn(0);
507 }
508 
509 #undef __FUNCT__
510 #define __FUNCT__ "PCBDDCSubSchursInit"
511 PetscErrorCode PCBDDCSubSchursInit(PCBDDCSubSchurs sub_schurs, Mat A, Mat S, IS is_I, IS is_B, PCBDDCGraph graph, ISLocalToGlobalMapping BtoNmap, PetscInt seqthreshold)
512 {
513   IS                  *faces,*edges,*all_cc;
514   PetscInt            *index_sequential,*index_parallel;
515   PetscInt            *auxlocal_sequential,*auxlocal_parallel;
516   PetscInt            *auxglobal_sequential,*auxglobal_parallel;
517   PetscInt            *auxmapping;//,*idxs;
518   PetscInt            i,max_subset_size;
519   PetscInt            n_sequential_problems,n_local_sequential_problems,n_parallel_problems,n_local_parallel_problems;
520   PetscInt            n_faces,n_edges,n_all_cc;
521   PetscBool           is_sorted;
522   PetscErrorCode  ierr;
523 
524   PetscFunctionBegin;
525   ierr = ISSorted(is_I,&is_sorted);CHKERRQ(ierr);
526   if (!is_sorted) {
527     SETERRQ(PetscObjectComm((PetscObject)is_I),PETSC_ERR_PLIB,"IS for I dofs should be shorted");
528   }
529   ierr = ISSorted(is_B,&is_sorted);CHKERRQ(ierr);
530   if (!is_sorted) {
531     SETERRQ(PetscObjectComm((PetscObject)is_B),PETSC_ERR_PLIB,"IS for B dofs should be shorted");
532   }
533 
534   /* reset any previous data */
535   ierr = PCBDDCSubSchursReset(sub_schurs);CHKERRQ(ierr);
536 
537   /* get index sets for faces and edges */
538   ierr = PCBDDCGraphGetCandidatesIS(graph,&n_faces,&faces,&n_edges,&edges,NULL);CHKERRQ(ierr);
539   n_all_cc = n_faces+n_edges;
540   ierr = PetscMalloc1(n_all_cc,&all_cc);CHKERRQ(ierr);
541   for (i=0;i<n_faces;i++) {
542     all_cc[i] = faces[i];
543   }
544   for (i=0;i<n_edges;i++) {
545     all_cc[n_faces+i] = edges[i];
546   }
547   ierr = PetscFree(faces);CHKERRQ(ierr);
548   ierr = PetscFree(edges);CHKERRQ(ierr);
549 
550   /* map interface's subsets */
551   max_subset_size = 0;
552   for (i=0;i<n_all_cc;i++) {
553     PetscInt subset_size;
554     ierr = ISGetLocalSize(all_cc[i],&subset_size);CHKERRQ(ierr);
555     max_subset_size = PetscMax(max_subset_size,subset_size);
556   }
557   ierr = PetscMalloc1(max_subset_size,&auxmapping);CHKERRQ(ierr);
558   ierr = PetscMalloc2(graph->ncc,&auxlocal_sequential,
559                       graph->ncc,&auxlocal_parallel);CHKERRQ(ierr);
560   ierr = PetscMalloc2(graph->ncc,&index_sequential,
561                       graph->ncc,&index_parallel);CHKERRQ(ierr);
562 
563   /* if threshold is negative uses all sequential problems (possibly using MUMPS) */
564   sub_schurs->use_mumps = PETSC_FALSE;
565   if (seqthreshold < 0) {
566     seqthreshold = max_subset_size;
567 #if defined(PETSC_HAVE_MUMPS)
568     sub_schurs->use_mumps = !!A;
569 #endif
570   }
571 
572 
573   /* determine which problem has to be solved in parallel or sequentially */
574   n_local_sequential_problems = 0;
575   n_local_parallel_problems = 0;
576   for (i=0;i<n_all_cc;i++) {
577     PetscInt       subset_size,j,min_loc = 0;
578     const PetscInt *idxs;
579 
580     ierr = ISGetLocalSize(all_cc[i],&subset_size);CHKERRQ(ierr);
581     ierr = ISGetIndices(all_cc[i],&idxs);CHKERRQ(ierr);
582     ierr = ISLocalToGlobalMappingApply(graph->l2gmap,subset_size,idxs,auxmapping);CHKERRQ(ierr);
583     for (j=1;j<subset_size;j++) {
584       if (auxmapping[j]<auxmapping[min_loc]) {
585         min_loc = j;
586       }
587     }
588     if (subset_size > seqthreshold) {
589       index_parallel[n_local_parallel_problems] = i;
590       auxlocal_parallel[n_local_parallel_problems] = idxs[min_loc];
591       n_local_parallel_problems++;
592     } else {
593       index_sequential[n_local_sequential_problems] = i;
594       auxlocal_sequential[n_local_sequential_problems] = idxs[min_loc];
595       n_local_sequential_problems++;
596     }
597     ierr = ISRestoreIndices(all_cc[i],&idxs);CHKERRQ(ierr);
598   }
599 
600   /* Number parallel problems */
601   auxglobal_parallel = 0;
602   ierr = PCBDDCSubsetNumbering(PetscObjectComm((PetscObject)graph->l2gmap),graph->l2gmap,n_local_parallel_problems,auxlocal_parallel,PETSC_NULL,&n_parallel_problems,&auxglobal_parallel);CHKERRQ(ierr);
603 
604   /* Number sequential problems */
605   auxglobal_sequential = 0;
606   ierr = PCBDDCSubsetNumbering(PetscObjectComm((PetscObject)graph->l2gmap),graph->l2gmap,n_local_sequential_problems,auxlocal_sequential,PETSC_NULL,&n_sequential_problems,&auxglobal_sequential);CHKERRQ(ierr);
607 
608   /* update info in sub_schurs */
609   if (sub_schurs->use_mumps && A) {
610     ierr = PetscObjectReference((PetscObject)A);CHKERRQ(ierr);
611     sub_schurs->A = A;
612   }
613   ierr = PetscObjectReference((PetscObject)S);CHKERRQ(ierr);
614   sub_schurs->S = S;
615   ierr = PetscObjectReference((PetscObject)is_I);CHKERRQ(ierr);
616   sub_schurs->is_I = is_I;
617   ierr = PetscObjectReference((PetscObject)is_B);CHKERRQ(ierr);
618   sub_schurs->is_B = is_B;
619   ierr = PetscObjectReference((PetscObject)graph->l2gmap);CHKERRQ(ierr);
620   sub_schurs->l2gmap = graph->l2gmap;
621   ierr = PetscObjectReference((PetscObject)BtoNmap);CHKERRQ(ierr);
622   sub_schurs->BtoNmap = BtoNmap;
623   sub_schurs->n_subs_seq = n_local_sequential_problems;
624   sub_schurs->n_subs_par = n_local_parallel_problems;
625   sub_schurs->n_subs_seq_g = n_sequential_problems;
626   sub_schurs->n_subs_par_g = n_parallel_problems;
627   sub_schurs->n_subs = sub_schurs->n_subs_seq + sub_schurs->n_subs_par;
628   sub_schurs->is_subs = all_cc;
629   sub_schurs->index_sequential = index_sequential;
630   sub_schurs->index_parallel = index_parallel;
631   sub_schurs->auxglobal_sequential = auxglobal_sequential;
632   sub_schurs->auxglobal_parallel = auxglobal_parallel;
633 
634   /* free workspace */
635   ierr = PetscFree(auxmapping);CHKERRQ(ierr);
636   ierr = PetscFree2(auxlocal_sequential,auxlocal_parallel);CHKERRQ(ierr);
637 
638   PetscFunctionReturn(0);
639 }
640 
641 #undef __FUNCT__
642 #define __FUNCT__ "PCBDDCSubSchursCreate"
643 PetscErrorCode PCBDDCSubSchursCreate(PCBDDCSubSchurs *sub_schurs)
644 {
645   PCBDDCSubSchurs schurs_ctx;
646   PetscErrorCode  ierr;
647 
648   PetscFunctionBegin;
649   ierr = PetscNew(&schurs_ctx);CHKERRQ(ierr);
650   schurs_ctx->n_subs = 0;
651   *sub_schurs = schurs_ctx;
652   PetscFunctionReturn(0);
653 }
654 
655 #undef __FUNCT__
656 #define __FUNCT__ "PCBDDCSubSchursDestroy"
657 PetscErrorCode PCBDDCSubSchursDestroy(PCBDDCSubSchurs *sub_schurs)
658 {
659   PetscErrorCode ierr;
660 
661   PetscFunctionBegin;
662   ierr = PCBDDCSubSchursReset(*sub_schurs);CHKERRQ(ierr);
663   ierr = PetscFree(*sub_schurs);CHKERRQ(ierr);
664   PetscFunctionReturn(0);
665 }
666 
667 #undef __FUNCT__
668 #define __FUNCT__ "PCBDDCSubSchursReset"
669 PetscErrorCode PCBDDCSubSchursReset(PCBDDCSubSchurs sub_schurs)
670 {
671   PetscInt       i;
672   PetscErrorCode ierr;
673 
674   PetscFunctionBegin;
675   ierr = MatDestroy(&sub_schurs->A);CHKERRQ(ierr);
676   ierr = MatDestroy(&sub_schurs->S);CHKERRQ(ierr);
677   ierr = ISDestroy(&sub_schurs->is_I);CHKERRQ(ierr);
678   ierr = ISDestroy(&sub_schurs->is_B);CHKERRQ(ierr);
679   ierr = ISLocalToGlobalMappingDestroy(&sub_schurs->l2gmap);CHKERRQ(ierr);
680   ierr = ISLocalToGlobalMappingDestroy(&sub_schurs->BtoNmap);CHKERRQ(ierr);
681   ierr = MatDestroy(&sub_schurs->S_Ej_all);CHKERRQ(ierr);
682   ierr = MatDestroy(&sub_schurs->sum_S_Ej_all);CHKERRQ(ierr);
683   ierr = ISDestroy(&sub_schurs->is_Ej_all);CHKERRQ(ierr);
684   for (i=0;i<sub_schurs->n_subs;i++) {
685     ierr = ISDestroy(&sub_schurs->is_subs[i]);CHKERRQ(ierr);
686     ierr = ISDestroy(&sub_schurs->is_AEj_B[i]);CHKERRQ(ierr);
687     ierr = MatDestroy(&sub_schurs->S_Ej[i]);CHKERRQ(ierr);
688     ierr = VecDestroy(&sub_schurs->work1[i]);CHKERRQ(ierr);
689     ierr = VecDestroy(&sub_schurs->work2[i]);CHKERRQ(ierr);
690   }
691   ierr = ISDestroy(&sub_schurs->is_I_layer);CHKERRQ(ierr);
692   if (sub_schurs->n_subs) {
693     ierr = PetscFree(sub_schurs->is_subs);CHKERRQ(ierr);
694     ierr = PetscFree4(sub_schurs->is_AEj_B,sub_schurs->S_Ej,sub_schurs->work1,sub_schurs->work2);CHKERRQ(ierr);
695     ierr = PetscFree2(sub_schurs->index_sequential,sub_schurs->index_parallel);CHKERRQ(ierr);
696     ierr = PetscFree(sub_schurs->auxglobal_sequential);CHKERRQ(ierr);
697     ierr = PetscFree(sub_schurs->auxglobal_parallel);CHKERRQ(ierr);
698   }
699   sub_schurs->n_subs = 0;
700   PetscFunctionReturn(0);
701 }
702 
703 #undef __FUNCT__
704 #define __FUNCT__ "PCBDDCAdjGetNextLayer_Private"
705 PETSC_STATIC_INLINE PetscErrorCode PCBDDCAdjGetNextLayer_Private(PetscInt* queue_tip,PetscInt n_prev,PetscBT touched,PetscInt* xadj,PetscInt* adjncy,PetscInt* n_added)
706 {
707   PetscInt       i,j,n;
708   PetscErrorCode ierr;
709 
710   PetscFunctionBegin;
711   n = 0;
712   for (i=-n_prev;i<0;i++) {
713     PetscInt start_dof = queue_tip[i];
714     for (j=xadj[start_dof];j<xadj[start_dof+1];j++) {
715       PetscInt dof = adjncy[j];
716       if (!PetscBTLookup(touched,dof)) {
717         ierr = PetscBTSet(touched,dof);CHKERRQ(ierr);
718         queue_tip[n] = dof;
719         n++;
720       }
721     }
722   }
723   *n_added = n;
724   PetscFunctionReturn(0);
725 }
726