xref: /petsc/src/ksp/pc/impls/bddc/bddcschurs.c (revision 2bf68e3e0f2a61f71e7c65bee250bfa1c8ce0cdb)
1 #include <../src/ksp/pc/impls/bddc/bddc.h>
2 #include <../src/ksp/pc/impls/bddc/bddcprivate.h>
3 #include <petscblaslapack.h>
4 
5 PETSC_STATIC_INLINE PetscErrorCode PCBDDCAdjGetNextLayer_Private(PetscInt*,PetscInt,PetscBT,PetscInt*,PetscInt*,PetscInt*);
6 static PetscErrorCode PCBDDCComputeExplicitSchur(Mat,PetscBool,MatReuse,Mat*);
7 static PetscErrorCode PCBDDCReuseSolvers_Interior(PC,Vec,Vec);
8 static PetscErrorCode PCBDDCReuseSolvers_Correction(PC,Vec,Vec);
9 
10 /* if v2 is not present, correction is done in-place */
11 #undef __FUNCT__
12 #define __FUNCT__ "PCBDDCReuseSolversBenignAdapt"
13 PetscErrorCode PCBDDCReuseSolversBenignAdapt(PCBDDCReuseSolvers ctx, Vec v, Vec v2, PetscBool sol, PetscBool full)
14 {
15   PetscScalar    *array;
16   PetscScalar    *array2;
17   PetscErrorCode ierr;
18 
19   PetscFunctionBegin;
20   if (!ctx->benign_n) PetscFunctionReturn(0);
21   if (sol && full) {
22     PetscInt n_I,size_schur;
23 
24     /* get sizes */
25     ierr = MatGetSize(ctx->benign_csAIB,&size_schur,NULL);CHKERRQ(ierr);
26     ierr = VecGetSize(v,&n_I);CHKERRQ(ierr);
27     n_I = n_I - size_schur;
28     /* get schur sol from array */
29     ierr = VecGetArray(v,&array);CHKERRQ(ierr);
30     ierr = VecPlaceArray(ctx->benign_dummy_schur_vec,array+n_I);CHKERRQ(ierr);
31     ierr = VecRestoreArray(v,&array);CHKERRQ(ierr);
32     /* apply interior sol correction */
33     ierr = MatMultTranspose(ctx->benign_csAIB,ctx->benign_dummy_schur_vec,ctx->benign_corr_work);CHKERRQ(ierr);
34     ierr = VecResetArray(ctx->benign_dummy_schur_vec);CHKERRQ(ierr);
35     ierr = MatMultAdd(ctx->benign_AIIm1ones,ctx->benign_corr_work,v,v);CHKERRQ(ierr);
36   }
37   if (v2) {
38     PetscInt nl;
39 
40     ierr = VecGetArrayRead(v,(const PetscScalar**)&array);CHKERRQ(ierr);
41     ierr = VecGetLocalSize(v2,&nl);CHKERRQ(ierr);
42     ierr = VecGetArray(v2,&array2);CHKERRQ(ierr);
43     ierr = PetscMemcpy(array2,array,nl*sizeof(PetscScalar));CHKERRQ(ierr);
44   } else {
45     ierr = VecGetArray(v,&array);CHKERRQ(ierr);
46     array2 = array;
47   }
48   if (!sol) { /* change rhs */
49     PetscInt n;
50     for (n=0;n<ctx->benign_n;n++) {
51       PetscScalar    sum = 0.;
52       const PetscInt *cols;
53       PetscInt       nz,i;
54 
55       ierr = ISGetLocalSize(ctx->benign_zerodiag_subs[n],&nz);CHKERRQ(ierr);
56       ierr = ISGetIndices(ctx->benign_zerodiag_subs[n],&cols);CHKERRQ(ierr);
57       for (i=0;i<nz-1;i++) sum += array[cols[i]];
58 #if defined(PETSC_USE_COMPLEX)
59       sum = -(PetscRealPart(sum)/nz + PETSC_i*(PetscImaginaryPart(sum)/nz));
60 #else
61       sum = -sum/nz;
62 #endif
63       for (i=0;i<nz-1;i++) array2[cols[i]] += sum;
64       ctx->benign_save_vals[n] = array2[cols[nz-1]];
65       array2[cols[nz-1]] = sum;
66       ierr = ISRestoreIndices(ctx->benign_zerodiag_subs[n],&cols);CHKERRQ(ierr);
67     }
68   } else {
69     PetscInt n;
70     for (n=0;n<ctx->benign_n;n++) {
71       PetscScalar    sum = 0.;
72       const PetscInt *cols;
73       PetscInt       nz,i;
74       ierr = ISGetLocalSize(ctx->benign_zerodiag_subs[n],&nz);CHKERRQ(ierr);
75       ierr = ISGetIndices(ctx->benign_zerodiag_subs[n],&cols);CHKERRQ(ierr);
76       for (i=0;i<nz-1;i++) sum += array[cols[i]];
77 #if defined(PETSC_USE_COMPLEX)
78       sum = -(PetscRealPart(sum)/nz + PETSC_i*(PetscImaginaryPart(sum)/nz));
79 #else
80       sum = -sum/nz;
81 #endif
82       for (i=0;i<nz-1;i++) array2[cols[i]] += sum;
83       array2[cols[nz-1]] = ctx->benign_save_vals[n];
84       ierr = ISRestoreIndices(ctx->benign_zerodiag_subs[n],&cols);CHKERRQ(ierr);
85     }
86   }
87   if (v2) {
88     ierr = VecRestoreArrayRead(v,(const PetscScalar**)&array);CHKERRQ(ierr);
89     ierr = VecRestoreArray(v2,&array2);CHKERRQ(ierr);
90   } else {
91     ierr = VecRestoreArray(v,&array);CHKERRQ(ierr);
92   }
93   if (!sol && full) {
94     Vec      usedv;
95     PetscInt n_I,size_schur;
96 
97     /* get sizes */
98     ierr = MatGetSize(ctx->benign_csAIB,&size_schur,NULL);CHKERRQ(ierr);
99     ierr = VecGetSize(v,&n_I);CHKERRQ(ierr);
100     n_I = n_I - size_schur;
101     /* compute schur rhs correction */
102     if (v2) {
103       usedv = v2;
104     } else {
105       usedv = v;
106     }
107     /* apply schur rhs correction */
108     ierr = MatMultTranspose(ctx->benign_AIIm1ones,usedv,ctx->benign_corr_work);CHKERRQ(ierr);
109     ierr = VecGetArrayRead(usedv,(const PetscScalar**)&array);CHKERRQ(ierr);
110     ierr = VecPlaceArray(ctx->benign_dummy_schur_vec,array+n_I);CHKERRQ(ierr);
111     ierr = VecRestoreArrayRead(usedv,(const PetscScalar**)&array);CHKERRQ(ierr);
112     ierr = MatMultAdd(ctx->benign_csAIB,ctx->benign_corr_work,ctx->benign_dummy_schur_vec,ctx->benign_dummy_schur_vec);CHKERRQ(ierr);
113     ierr = VecResetArray(ctx->benign_dummy_schur_vec);CHKERRQ(ierr);
114   }
115   PetscFunctionReturn(0);
116 }
117 
118 #undef __FUNCT__
119 #define __FUNCT__ "PCBDDCReuseSolvers_Solve_Private"
120 static PetscErrorCode PCBDDCReuseSolvers_Solve_Private(PC pc, Vec rhs, Vec sol, PetscBool transpose, PetscBool full)
121 {
122   PCBDDCReuseSolvers ctx;
123   PetscBool          copy = PETSC_FALSE;
124   PetscErrorCode     ierr;
125 
126   PetscFunctionBegin;
127   ierr = PCShellGetContext(pc,(void **)&ctx);CHKERRQ(ierr);
128   if (full) {
129 #if defined(PETSC_HAVE_MUMPS)
130     ierr = MatMumpsSetIcntl(ctx->F,26,-1);CHKERRQ(ierr);
131 #endif
132 #if defined(PETSC_HAVE_MKL_PARDISO)
133     ierr = MatMkl_PardisoSetCntl(ctx->F,70,0);CHKERRQ(ierr);
134 #endif
135     copy = ctx->has_vertices;
136   } else { /* interior solver */
137 #if defined(PETSC_HAVE_MUMPS)
138     ierr = MatMumpsSetIcntl(ctx->F,26,0);CHKERRQ(ierr);
139 #endif
140 #if defined(PETSC_HAVE_MKL_PARDISO)
141     ierr = MatMkl_PardisoSetCntl(ctx->F,70,1);CHKERRQ(ierr);
142 #endif
143     copy = PETSC_TRUE;
144   }
145   /* copy rhs into factored matrix workspace */
146   if (copy) {
147     PetscInt    n;
148     PetscScalar *array,*array_solver;
149 
150     ierr = VecGetLocalSize(rhs,&n);CHKERRQ(ierr);
151     ierr = VecGetArrayRead(rhs,(const PetscScalar**)&array);CHKERRQ(ierr);
152     ierr = VecGetArray(ctx->rhs,&array_solver);CHKERRQ(ierr);
153     ierr = PetscMemcpy(array_solver,array,n*sizeof(PetscScalar));CHKERRQ(ierr);
154     ierr = VecRestoreArray(ctx->rhs,&array_solver);CHKERRQ(ierr);
155     ierr = VecRestoreArrayRead(rhs,(const PetscScalar**)&array);CHKERRQ(ierr);
156 
157     ierr = PCBDDCReuseSolversBenignAdapt(ctx,ctx->rhs,NULL,PETSC_FALSE,full);CHKERRQ(ierr);
158     if (transpose) {
159       ierr = MatSolveTranspose(ctx->F,ctx->rhs,ctx->sol);CHKERRQ(ierr);
160     } else {
161       ierr = MatSolve(ctx->F,ctx->rhs,ctx->sol);CHKERRQ(ierr);
162     }
163     ierr = PCBDDCReuseSolversBenignAdapt(ctx,ctx->sol,NULL,PETSC_TRUE,full);CHKERRQ(ierr);
164 
165     /* get back data to caller worskpace */
166     ierr = VecGetArrayRead(ctx->sol,(const PetscScalar**)&array_solver);CHKERRQ(ierr);
167     ierr = VecGetArray(sol,&array);CHKERRQ(ierr);
168     ierr = PetscMemcpy(array,array_solver,n*sizeof(PetscScalar));CHKERRQ(ierr);
169     ierr = VecRestoreArray(sol,&array);CHKERRQ(ierr);
170     ierr = VecRestoreArrayRead(ctx->sol,(const PetscScalar**)&array_solver);CHKERRQ(ierr);
171   } else {
172     if (ctx->benign_n) {
173       ierr = PCBDDCReuseSolversBenignAdapt(ctx,rhs,ctx->rhs,PETSC_FALSE,full);CHKERRQ(ierr);
174       if (transpose) {
175         ierr = MatSolveTranspose(ctx->F,ctx->rhs,sol);CHKERRQ(ierr);
176       } else {
177         ierr = MatSolve(ctx->F,ctx->rhs,sol);CHKERRQ(ierr);
178       }
179       ierr = PCBDDCReuseSolversBenignAdapt(ctx,sol,NULL,PETSC_TRUE,full);CHKERRQ(ierr);
180     } else {
181       if (transpose) {
182         ierr = MatSolveTranspose(ctx->F,rhs,sol);CHKERRQ(ierr);
183       } else {
184         ierr = MatSolve(ctx->F,rhs,sol);CHKERRQ(ierr);
185       }
186     }
187   }
188   /* restore defaults */
189 #if defined(PETSC_HAVE_MUMPS)
190   ierr = MatMumpsSetIcntl(ctx->F,26,-1);CHKERRQ(ierr);
191 #endif
192 #if defined(PETSC_HAVE_MKL_PARDISO)
193   ierr = MatMkl_PardisoSetCntl(ctx->F,70,0);CHKERRQ(ierr);
194 #endif
195   PetscFunctionReturn(0);
196 }
197 
198 #undef __FUNCT__
199 #define __FUNCT__ "PCBDDCReuseSolvers_Correction"
200 static PetscErrorCode PCBDDCReuseSolvers_Correction(PC pc, Vec rhs, Vec sol)
201 {
202   PetscErrorCode   ierr;
203 
204   PetscFunctionBegin;
205   ierr = PCBDDCReuseSolvers_Solve_Private(pc,rhs,sol,PETSC_FALSE,PETSC_TRUE);CHKERRQ(ierr);
206   PetscFunctionReturn(0);
207 }
208 
209 #undef __FUNCT__
210 #define __FUNCT__ "PCBDDCReuseSolvers_CorrectionTranspose"
211 static PetscErrorCode PCBDDCReuseSolvers_CorrectionTranspose(PC pc, Vec rhs, Vec sol)
212 {
213   PetscErrorCode   ierr;
214 
215   PetscFunctionBegin;
216   ierr = PCBDDCReuseSolvers_Solve_Private(pc,rhs,sol,PETSC_TRUE,PETSC_TRUE);CHKERRQ(ierr);
217   PetscFunctionReturn(0);
218 }
219 
220 #undef __FUNCT__
221 #define __FUNCT__ "PCBDDCReuseSolvers_Interior"
222 static PetscErrorCode PCBDDCReuseSolvers_Interior(PC pc, Vec rhs, Vec sol)
223 {
224   PetscErrorCode   ierr;
225 
226   PetscFunctionBegin;
227   ierr = PCBDDCReuseSolvers_Solve_Private(pc,rhs,sol,PETSC_FALSE,PETSC_FALSE);CHKERRQ(ierr);
228   PetscFunctionReturn(0);
229 }
230 
231 #undef __FUNCT__
232 #define __FUNCT__ "PCBDDCReuseSolvers_InteriorTranspose"
233 static PetscErrorCode PCBDDCReuseSolvers_InteriorTranspose(PC pc, Vec rhs, Vec sol)
234 {
235   PetscErrorCode   ierr;
236 
237   PetscFunctionBegin;
238   ierr = PCBDDCReuseSolvers_Solve_Private(pc,rhs,sol,PETSC_TRUE,PETSC_FALSE);CHKERRQ(ierr);
239   PetscFunctionReturn(0);
240 }
241 
242 #undef __FUNCT__
243 #define __FUNCT__ "PCBDDCReuseSolversReset"
244 static PetscErrorCode PCBDDCReuseSolversReset(PCBDDCReuseSolvers reuse)
245 {
246   PetscInt       i;
247   PetscErrorCode ierr;
248 
249   PetscFunctionBegin;
250   ierr = MatDestroy(&reuse->F);CHKERRQ(ierr);
251   ierr = VecDestroy(&reuse->sol);CHKERRQ(ierr);
252   ierr = VecDestroy(&reuse->rhs);CHKERRQ(ierr);
253   ierr = PCDestroy(&reuse->interior_solver);CHKERRQ(ierr);
254   ierr = PCDestroy(&reuse->correction_solver);CHKERRQ(ierr);
255   ierr = ISDestroy(&reuse->is_R);CHKERRQ(ierr);
256   ierr = ISDestroy(&reuse->is_B);CHKERRQ(ierr);
257   ierr = VecScatterDestroy(&reuse->correction_scatter_B);CHKERRQ(ierr);
258   ierr = VecDestroy(&reuse->sol_B);CHKERRQ(ierr);
259   ierr = VecDestroy(&reuse->rhs_B);CHKERRQ(ierr);
260   for (i=0;i<reuse->benign_n;i++) {
261     ierr = ISDestroy(&reuse->benign_zerodiag_subs[i]);CHKERRQ(ierr);
262   }
263   ierr = PetscFree(reuse->benign_zerodiag_subs);CHKERRQ(ierr);
264   ierr = PetscFree(reuse->benign_save_vals);CHKERRQ(ierr);
265   ierr = MatDestroy(&reuse->benign_csAIB);CHKERRQ(ierr);
266   ierr = MatDestroy(&reuse->benign_AIIm1ones);CHKERRQ(ierr);
267   ierr = VecDestroy(&reuse->benign_corr_work);CHKERRQ(ierr);
268   ierr = VecDestroy(&reuse->benign_dummy_schur_vec);CHKERRQ(ierr);
269   PetscFunctionReturn(0);
270 }
271 
272 #undef __FUNCT__
273 #define __FUNCT__ "PCBDDCComputeExplicitSchur"
274 static PetscErrorCode PCBDDCComputeExplicitSchur(Mat M, PetscBool issym, MatReuse reuse, Mat *S)
275 {
276   Mat            B, C, D, Bd, Cd, AinvBd;
277   KSP            ksp;
278   PC             pc;
279   PetscBool      isLU, isILU, isCHOL, Bdense, Cdense;
280   PetscReal      fill = 2.0;
281   PetscInt       n_I;
282   PetscMPIInt    size;
283   PetscErrorCode ierr;
284 
285   PetscFunctionBegin;
286   ierr = MPI_Comm_size(PetscObjectComm((PetscObject)M),&size);CHKERRQ(ierr);
287   if (size != 1) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Not for parallel matrices");
288   if (reuse == MAT_REUSE_MATRIX) {
289     PetscBool Sdense;
290 
291     ierr = PetscObjectTypeCompare((PetscObject)*S, MATSEQDENSE, &Sdense);CHKERRQ(ierr);
292     if (!Sdense) SETERRQ(PetscObjectComm((PetscObject)M),PETSC_ERR_SUP,"S should dense");
293   }
294   ierr = MatSchurComplementGetSubMatrices(M, NULL, NULL, &B, &C, &D);CHKERRQ(ierr);
295   ierr = MatSchurComplementGetKSP(M, &ksp);CHKERRQ(ierr);
296   ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
297   ierr = PetscObjectTypeCompare((PetscObject) pc, PCLU, &isLU);CHKERRQ(ierr);
298   ierr = PetscObjectTypeCompare((PetscObject) pc, PCILU, &isILU);CHKERRQ(ierr);
299   ierr = PetscObjectTypeCompare((PetscObject) pc, PCCHOLESKY, &isCHOL);CHKERRQ(ierr);
300   ierr = PetscObjectTypeCompare((PetscObject) B, MATSEQDENSE, &Bdense);CHKERRQ(ierr);
301   ierr = PetscObjectTypeCompare((PetscObject) C, MATSEQDENSE, &Cdense);CHKERRQ(ierr);
302   ierr = MatGetSize(B,&n_I,NULL);CHKERRQ(ierr);
303   if (n_I) {
304     if (!Bdense) {
305       ierr = MatConvert(B, MATSEQDENSE, MAT_INITIAL_MATRIX, &Bd);CHKERRQ(ierr);
306     } else {
307       Bd = B;
308     }
309 
310     if (isLU || isILU || isCHOL) {
311       Mat fact;
312       ierr = KSPSetUp(ksp);CHKERRQ(ierr);
313       ierr = PCFactorGetMatrix(pc, &fact);CHKERRQ(ierr);
314       ierr = MatDuplicate(Bd, MAT_DO_NOT_COPY_VALUES, &AinvBd);CHKERRQ(ierr);
315       ierr = MatMatSolve(fact, Bd, AinvBd);CHKERRQ(ierr);
316     } else {
317       PetscBool ex = PETSC_TRUE;
318 
319       if (ex) {
320         Mat Ainvd;
321 
322         ierr = PCComputeExplicitOperator(pc, &Ainvd);CHKERRQ(ierr);
323         ierr = MatMatMult(Ainvd, Bd, MAT_INITIAL_MATRIX, fill, &AinvBd);CHKERRQ(ierr);
324         ierr = MatDestroy(&Ainvd);CHKERRQ(ierr);
325       } else {
326         Vec         sol,rhs;
327         PetscScalar *arrayrhs,*arraysol;
328         PetscInt    i,nrhs,n;
329 
330         ierr = MatDuplicate(Bd, MAT_DO_NOT_COPY_VALUES, &AinvBd);CHKERRQ(ierr);
331         ierr = MatGetSize(Bd,&n,&nrhs);CHKERRQ(ierr);
332         ierr = MatDenseGetArray(Bd,&arrayrhs);CHKERRQ(ierr);
333         ierr = MatDenseGetArray(AinvBd,&arraysol);CHKERRQ(ierr);
334         ierr = KSPGetSolution(ksp,&sol);CHKERRQ(ierr);
335         ierr = KSPGetRhs(ksp,&rhs);CHKERRQ(ierr);
336         for (i=0;i<nrhs;i++) {
337           ierr = VecPlaceArray(rhs,arrayrhs+i*n);CHKERRQ(ierr);
338           ierr = VecPlaceArray(sol,arraysol+i*n);CHKERRQ(ierr);
339           ierr = KSPSolve(ksp,rhs,sol);CHKERRQ(ierr);
340           ierr = VecResetArray(rhs);CHKERRQ(ierr);
341           ierr = VecResetArray(sol);CHKERRQ(ierr);
342         }
343         ierr = MatDenseRestoreArray(Bd,&arrayrhs);CHKERRQ(ierr);
344         ierr = MatDenseRestoreArray(AinvBd,&arrayrhs);CHKERRQ(ierr);
345       }
346     }
347     if (!Bdense & !issym) {
348       ierr = MatDestroy(&Bd);CHKERRQ(ierr);
349     }
350 
351     if (!issym) {
352       if (!Cdense) {
353         ierr = MatConvert(C, MATSEQDENSE, MAT_INITIAL_MATRIX, &Cd);CHKERRQ(ierr);
354       } else {
355         Cd = C;
356       }
357       ierr = MatMatMult(Cd, AinvBd, reuse, fill, S);CHKERRQ(ierr);
358       if (!Cdense) {
359         ierr = MatDestroy(&Cd);CHKERRQ(ierr);
360       }
361     } else {
362       ierr = MatTransposeMatMult(Bd, AinvBd, reuse, fill, S);CHKERRQ(ierr);
363       if (!Bdense) {
364         ierr = MatDestroy(&Bd);CHKERRQ(ierr);
365       }
366     }
367     ierr = MatDestroy(&AinvBd);CHKERRQ(ierr);
368   }
369 
370   if (D) {
371     Mat       Dd;
372     PetscBool Ddense;
373 
374     ierr = PetscObjectTypeCompare((PetscObject)D,MATSEQDENSE,&Ddense);CHKERRQ(ierr);
375     if (!Ddense) {
376       ierr = MatConvert(D, MATSEQDENSE, MAT_INITIAL_MATRIX, &Dd);CHKERRQ(ierr);
377     } else {
378       Dd = D;
379     }
380     if (n_I) {
381       ierr = MatAYPX(*S,-1.0,Dd,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
382     } else {
383       if (reuse == MAT_INITIAL_MATRIX) {
384         ierr = MatDuplicate(Dd,MAT_COPY_VALUES,S);CHKERRQ(ierr);
385       } else {
386         ierr = MatCopy(Dd,*S,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
387       }
388     }
389     if (!Ddense) {
390       ierr = MatDestroy(&Dd);CHKERRQ(ierr);
391     }
392   } else {
393     ierr = MatScale(*S,-1.0);CHKERRQ(ierr);
394   }
395   PetscFunctionReturn(0);
396 }
397 
398 #undef __FUNCT__
399 #define __FUNCT__ "PCBDDCSubSchursSetUp"
400 PetscErrorCode PCBDDCSubSchursSetUp(PCBDDCSubSchurs sub_schurs, Mat Ain, Mat Sin, PetscBool exact_schur, PetscInt xadj[], PetscInt adjncy[], PetscInt nlayers, Vec scaling, PetscBool compute_Stilda, PetscBool reuse_solvers, PetscBool benign_trick, PetscInt benign_n, PetscInt benign_p0_lidx[], IS benign_zerodiag_subs[], Mat change, IS change_primal)
401 {
402   Mat                    F,A_II,A_IB,A_BI,A_BB,AE_II;
403   Mat                    S_all;
404   Mat                    global_schur_subsets,work_mat,*submats;
405   ISLocalToGlobalMapping l2gmap_subsets;
406   IS                     is_I,is_I_layer;
407   IS                     all_subsets,all_subsets_mult,all_subsets_n;
408   PetscInt               *nnz,*all_local_idx_N;
409   PetscInt               *auxnum1,*auxnum2;
410   PetscInt               i,subset_size,max_subset_size;
411   PetscInt               n_B,extra,local_size,global_size;
412   PetscBLASInt           B_N,B_ierr,B_lwork,*pivots;
413   PetscScalar            *Bwork;
414   PetscSubcomm           subcomm;
415   PetscMPIInt            color,rank;
416   MPI_Comm               comm_n;
417   PetscBool              deluxe = PETSC_TRUE, use_getr = PETSC_FALSE;
418   PetscErrorCode         ierr;
419 
420   PetscFunctionBegin;
421   ierr = MatDestroy(&sub_schurs->A);CHKERRQ(ierr);
422   ierr = MatDestroy(&sub_schurs->S);CHKERRQ(ierr);
423 
424   sub_schurs->is_hermitian = PETSC_TRUE;
425   sub_schurs->is_posdef    = PETSC_TRUE;
426   if (benign_trick) sub_schurs->is_posdef = PETSC_FALSE;
427   ierr = PetscOptionsBegin(PetscObjectComm((PetscObject)sub_schurs->l2gmap),sub_schurs->prefix,"BDDC sub_schurs options","PC");CHKERRQ(ierr);
428   ierr = PetscOptionsBool("-sub_schurs_hermitian","Hermitian problem",NULL,sub_schurs->is_hermitian,&sub_schurs->is_hermitian,NULL);CHKERRQ(ierr);
429   ierr = PetscOptionsBool("-sub_schurs_posdef","Positive definite problem",NULL,sub_schurs->is_posdef,&sub_schurs->is_posdef,NULL);CHKERRQ(ierr);
430   ierr = PetscOptionsEnd();CHKERRQ(ierr);
431 
432   /* convert matrix if needed */
433   if (Ain) {
434     PetscBool isseqaij;
435     ierr = PetscObjectTypeCompare((PetscObject)Ain,MATSEQAIJ,&isseqaij);CHKERRQ(ierr);
436     if (isseqaij) {
437       ierr = PetscObjectReference((PetscObject)Ain);CHKERRQ(ierr);
438       sub_schurs->A = Ain;
439     } else {
440       ierr = MatConvert(Ain,MATSEQAIJ,MAT_INITIAL_MATRIX,&sub_schurs->A);CHKERRQ(ierr);
441     }
442   }
443 
444   ierr = PetscObjectReference((PetscObject)Sin);CHKERRQ(ierr);
445   sub_schurs->S = Sin;
446   if (sub_schurs->schur_explicit) {
447     sub_schurs->schur_explicit = (PetscBool)(!!sub_schurs->A);
448   }
449 
450   /* preliminary checks */
451   if (!sub_schurs->schur_explicit && compute_Stilda) SETERRQ(PetscObjectComm((PetscObject)sub_schurs->l2gmap),PETSC_ERR_SUP,"Adaptive selection of constraints requires MUMPS and/or MKL_PARDISO");
452 
453   /* restrict work on active processes */
454   color = 0;
455   if (!sub_schurs->n_subs) color = 1; /* this can happen if we are in a multilevel case or if the subdomain is disconnected */
456   ierr = MPI_Comm_rank(PetscObjectComm((PetscObject)sub_schurs->l2gmap),&rank);CHKERRQ(ierr);
457   ierr = PetscSubcommCreate(PetscObjectComm((PetscObject)sub_schurs->l2gmap),&subcomm);CHKERRQ(ierr);
458   ierr = PetscSubcommSetNumber(subcomm,2);CHKERRQ(ierr);
459   ierr = PetscSubcommSetTypeGeneral(subcomm,color,rank);CHKERRQ(ierr);
460   ierr = PetscCommDuplicate(PetscSubcommChild(subcomm),&comm_n,NULL);CHKERRQ(ierr);
461   ierr = PetscSubcommDestroy(&subcomm);CHKERRQ(ierr);
462   if (!sub_schurs->n_subs) {
463     ierr = PetscCommDestroy(&comm_n);CHKERRQ(ierr);
464     PetscFunctionReturn(0);
465   }
466   /* ierr = PetscCommDuplicate(PetscObjectComm((PetscObject)sub_schurs->l2gmap),&comm_n,NULL);CHKERRQ(ierr); */
467 
468   /* get Schur complement matrices */
469   if (!sub_schurs->schur_explicit) {
470     Mat       tA_IB,tA_BI,tA_BB;
471     PetscBool isseqsbaij;
472     ierr = MatSchurComplementGetSubMatrices(sub_schurs->S,&A_II,NULL,&tA_IB,&tA_BI,&tA_BB);CHKERRQ(ierr);
473     ierr = PetscObjectTypeCompare((PetscObject)tA_BB,MATSEQSBAIJ,&isseqsbaij);CHKERRQ(ierr);
474     if (isseqsbaij) {
475       ierr = MatConvert(tA_BB,MATSEQAIJ,MAT_INITIAL_MATRIX,&A_BB);CHKERRQ(ierr);
476       ierr = MatConvert(tA_IB,MATSEQAIJ,MAT_INITIAL_MATRIX,&A_IB);CHKERRQ(ierr);
477       ierr = MatConvert(tA_BI,MATSEQAIJ,MAT_INITIAL_MATRIX,&A_BI);CHKERRQ(ierr);
478     } else {
479       ierr = PetscObjectReference((PetscObject)tA_BB);CHKERRQ(ierr);
480       A_BB = tA_BB;
481       ierr = PetscObjectReference((PetscObject)tA_IB);CHKERRQ(ierr);
482       A_IB = tA_IB;
483       ierr = PetscObjectReference((PetscObject)tA_BI);CHKERRQ(ierr);
484       A_BI = tA_BI;
485     }
486   } else {
487     A_II = NULL;
488     A_IB = NULL;
489     A_BI = NULL;
490     A_BB = NULL;
491   }
492   S_all = NULL;
493 
494   /* determine interior problems */
495   ierr = ISGetLocalSize(sub_schurs->is_I,&i);CHKERRQ(ierr);
496   if (nlayers >= 0 && i) { /* Interior problems can be different from the original one */
497     PetscBT                touched;
498     const PetscInt*        idx_B;
499     PetscInt               n_I,n_B,n_local_dofs,n_prev_added,j,layer,*local_numbering;
500 
501     if (!xadj) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Cannot request layering without adjacency");
502     /* get sizes */
503     ierr = ISGetLocalSize(sub_schurs->is_I,&n_I);CHKERRQ(ierr);
504     ierr = ISGetLocalSize(sub_schurs->is_B,&n_B);CHKERRQ(ierr);
505 
506     ierr = PetscMalloc1(n_I+n_B,&local_numbering);CHKERRQ(ierr);
507     ierr = PetscBTCreate(n_I+n_B,&touched);CHKERRQ(ierr);
508     ierr = PetscBTMemzero(n_I+n_B,touched);CHKERRQ(ierr);
509 
510     /* all boundary dofs must be skipped when adding layers */
511     ierr = ISGetIndices(sub_schurs->is_B,&idx_B);CHKERRQ(ierr);
512     for (j=0;j<n_B;j++) {
513       ierr = PetscBTSet(touched,idx_B[j]);CHKERRQ(ierr);
514     }
515     ierr = PetscMemcpy(local_numbering,idx_B,n_B*sizeof(PetscInt));CHKERRQ(ierr);
516     ierr = ISRestoreIndices(sub_schurs->is_B,&idx_B);CHKERRQ(ierr);
517 
518     /* add prescribed number of layers of dofs */
519     n_local_dofs = n_B;
520     n_prev_added = n_B;
521     for (layer=0;layer<nlayers;layer++) {
522       PetscInt n_added;
523       if (n_local_dofs == n_I+n_B) break;
524       if (n_local_dofs > n_I+n_B) 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);
525       ierr = PCBDDCAdjGetNextLayer_Private(local_numbering+n_local_dofs,n_prev_added,touched,xadj,adjncy,&n_added);CHKERRQ(ierr);
526       n_prev_added = n_added;
527       n_local_dofs += n_added;
528       if (!n_added) break;
529     }
530     ierr = PetscBTDestroy(&touched);CHKERRQ(ierr);
531 
532     /* IS for I layer dofs in original numbering */
533     ierr = ISCreateGeneral(PetscObjectComm((PetscObject)sub_schurs->is_I),n_local_dofs-n_B,local_numbering+n_B,PETSC_COPY_VALUES,&is_I_layer);CHKERRQ(ierr);
534     ierr = PetscFree(local_numbering);CHKERRQ(ierr);
535     ierr = ISSort(is_I_layer);CHKERRQ(ierr);
536     /* IS for I layer dofs in I numbering */
537     if (!sub_schurs->schur_explicit) {
538       ISLocalToGlobalMapping ItoNmap;
539       ierr = ISLocalToGlobalMappingCreateIS(sub_schurs->is_I,&ItoNmap);CHKERRQ(ierr);
540       ierr = ISGlobalToLocalMappingApplyIS(ItoNmap,IS_GTOLM_DROP,is_I_layer,&is_I);CHKERRQ(ierr);
541       ierr = ISLocalToGlobalMappingDestroy(&ItoNmap);CHKERRQ(ierr);
542 
543       /* II block */
544       ierr = MatGetSubMatrix(A_II,is_I,is_I,MAT_INITIAL_MATRIX,&AE_II);CHKERRQ(ierr);
545     }
546   } else {
547     PetscInt n_I;
548 
549     /* IS for I dofs in original numbering */
550     ierr = PetscObjectReference((PetscObject)sub_schurs->is_I);CHKERRQ(ierr);
551     is_I_layer = sub_schurs->is_I;
552 
553     /* IS for I dofs in I numbering (strided 1) */
554     if (!sub_schurs->schur_explicit) {
555       ierr = ISGetSize(sub_schurs->is_I,&n_I);CHKERRQ(ierr);
556       ierr = ISCreateStride(PetscObjectComm((PetscObject)sub_schurs->is_I),n_I,0,1,&is_I);CHKERRQ(ierr);
557 
558       /* II block is the same */
559       ierr = PetscObjectReference((PetscObject)A_II);CHKERRQ(ierr);
560       AE_II = A_II;
561     }
562   }
563 
564   /* Get info on subset sizes and sum of all subsets sizes */
565   max_subset_size = 0;
566   local_size = 0;
567   for (i=0;i<sub_schurs->n_subs;i++) {
568     ierr = ISGetLocalSize(sub_schurs->is_subs[i],&subset_size);CHKERRQ(ierr);
569     max_subset_size = PetscMax(subset_size,max_subset_size);
570     local_size += subset_size;
571   }
572 
573   /* Work arrays for local indices */
574   extra = 0;
575   ierr = ISGetLocalSize(sub_schurs->is_B,&n_B);CHKERRQ(ierr);
576   if (sub_schurs->schur_explicit && is_I_layer) {
577     ierr = ISGetLocalSize(is_I_layer,&extra);CHKERRQ(ierr);
578   }
579   ierr = PetscMalloc1(n_B+extra,&all_local_idx_N);CHKERRQ(ierr);
580   if (extra) {
581     const PetscInt *idxs;
582     ierr = ISGetIndices(is_I_layer,&idxs);CHKERRQ(ierr);
583     ierr = PetscMemcpy(all_local_idx_N,idxs,extra*sizeof(PetscInt));CHKERRQ(ierr);
584     ierr = ISRestoreIndices(is_I_layer,&idxs);CHKERRQ(ierr);
585   }
586   ierr = PetscMalloc1(local_size,&nnz);CHKERRQ(ierr);
587   ierr = PetscMalloc1(sub_schurs->n_subs,&auxnum1);CHKERRQ(ierr);
588   ierr = PetscMalloc1(sub_schurs->n_subs,&auxnum2);CHKERRQ(ierr);
589 
590   /* Get local indices in local numbering */
591   local_size = 0;
592   for (i=0;i<sub_schurs->n_subs;i++) {
593     PetscInt j;
594     const    PetscInt *idxs;
595 
596     ierr = ISGetLocalSize(sub_schurs->is_subs[i],&subset_size);CHKERRQ(ierr);
597     ierr = ISGetIndices(sub_schurs->is_subs[i],&idxs);CHKERRQ(ierr);
598     /* start (smallest in global ordering) and multiplicity */
599     auxnum1[i] = idxs[0];
600     auxnum2[i] = subset_size;
601     /* subset indices in local numbering */
602     ierr = PetscMemcpy(all_local_idx_N+local_size+extra,idxs,subset_size*sizeof(PetscInt));CHKERRQ(ierr);
603     ierr = ISRestoreIndices(sub_schurs->is_subs[i],&idxs);CHKERRQ(ierr);
604     for (j=0;j<subset_size;j++) nnz[local_size+j] = subset_size;
605     local_size += subset_size;
606   }
607 
608   /* allocate extra workspace needed only for GETRI */
609   if (local_size && !benign_trick && (!sub_schurs->is_hermitian || !sub_schurs->is_posdef)) {
610     PetscScalar  lwork,dummyscalar = 0.;
611     PetscBLASInt dummyint = 0;
612 
613     use_getr = PETSC_TRUE;
614     B_lwork = -1;
615     ierr = PetscBLASIntCast(local_size,&B_N);CHKERRQ(ierr);
616     ierr = PetscFPTrapPush(PETSC_FP_TRAP_OFF);CHKERRQ(ierr);
617     PetscStackCallBLAS("LAPACKgetri",LAPACKgetri_(&B_N,&dummyscalar,&B_N,&dummyint,&lwork,&B_lwork,&B_ierr));
618     ierr = PetscFPTrapPop();CHKERRQ(ierr);
619     if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in query to GETRI Lapack routine %d",(int)B_ierr);
620     ierr = PetscBLASIntCast((PetscInt)PetscRealPart(lwork),&B_lwork);CHKERRQ(ierr);
621     ierr = PetscMalloc2(B_lwork,&Bwork,B_N,&pivots);CHKERRQ(ierr);
622   } else {
623     Bwork = NULL;
624     pivots = NULL;
625   }
626 
627   /* prepare parallel matrices for summing up properly schurs on subsets */
628   ierr = ISCreateGeneral(comm_n,sub_schurs->n_subs,auxnum1,PETSC_OWN_POINTER,&all_subsets_n);CHKERRQ(ierr);
629   ierr = ISLocalToGlobalMappingApplyIS(sub_schurs->l2gmap,all_subsets_n,&all_subsets);CHKERRQ(ierr);
630   ierr = ISDestroy(&all_subsets_n);CHKERRQ(ierr);
631   ierr = ISCreateGeneral(comm_n,sub_schurs->n_subs,auxnum2,PETSC_OWN_POINTER,&all_subsets_mult);CHKERRQ(ierr);
632   ierr = ISRenumber(all_subsets,all_subsets_mult,&global_size,&all_subsets_n);CHKERRQ(ierr);
633   ierr = ISDestroy(&all_subsets);CHKERRQ(ierr);
634   ierr = ISDestroy(&all_subsets_mult);CHKERRQ(ierr);
635   ierr = ISGetLocalSize(all_subsets_n,&i);CHKERRQ(ierr);
636   if (i != local_size) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Invalid size of new subset! %D != %D",i,local_size);
637   ierr = ISLocalToGlobalMappingCreateIS(all_subsets_n,&l2gmap_subsets);CHKERRQ(ierr);
638   ierr = MatCreateIS(comm_n,1,PETSC_DECIDE,PETSC_DECIDE,global_size,global_size,l2gmap_subsets,NULL,&work_mat);CHKERRQ(ierr);
639   ierr = ISLocalToGlobalMappingDestroy(&l2gmap_subsets);CHKERRQ(ierr);
640   ierr = MatCreate(PetscObjectComm((PetscObject)work_mat),&global_schur_subsets);CHKERRQ(ierr);
641   ierr = MatSetSizes(global_schur_subsets,PETSC_DECIDE,PETSC_DECIDE,global_size,global_size);CHKERRQ(ierr);
642   ierr = MatSetType(global_schur_subsets,MATMPIAIJ);CHKERRQ(ierr);
643 
644   /* subset indices in local boundary numbering */
645   if (!sub_schurs->is_Ej_all) {
646     PetscInt *all_local_idx_B;
647 
648     ierr = PetscMalloc1(local_size,&all_local_idx_B);CHKERRQ(ierr);
649     ierr = ISGlobalToLocalMappingApply(sub_schurs->BtoNmap,IS_GTOLM_DROP,local_size,all_local_idx_N+extra,&subset_size,all_local_idx_B);CHKERRQ(ierr);
650     if (subset_size != local_size) SETERRQ2(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Error in sub_schurs serial (BtoNmap)! %D != %D\n",subset_size,local_size);
651     ierr = ISCreateGeneral(PETSC_COMM_SELF,local_size,all_local_idx_B,PETSC_OWN_POINTER,&sub_schurs->is_Ej_all);CHKERRQ(ierr);
652   }
653 
654   if (change) {
655     ISLocalToGlobalMapping BtoS;
656     IS                     change_primal_B;
657     IS                     change_primal_all;
658 
659     if (sub_schurs->change_primal_sub) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"This should not happen");
660     if (sub_schurs->change) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"This should not happen");
661     ierr = PetscMalloc1(sub_schurs->n_subs,&sub_schurs->change_primal_sub);CHKERRQ(ierr);
662     for (i=0;i<sub_schurs->n_subs;i++) {
663       ISLocalToGlobalMapping NtoS;
664       ierr = ISLocalToGlobalMappingCreateIS(sub_schurs->is_subs[i],&NtoS);CHKERRQ(ierr);
665       ierr = ISGlobalToLocalMappingApplyIS(NtoS,IS_GTOLM_DROP,change_primal,&sub_schurs->change_primal_sub[i]);CHKERRQ(ierr);
666       ierr = ISLocalToGlobalMappingDestroy(&NtoS);CHKERRQ(ierr);
667     }
668     ierr = ISGlobalToLocalMappingApplyIS(sub_schurs->BtoNmap,IS_GTOLM_DROP,change_primal,&change_primal_B);CHKERRQ(ierr);
669     ierr = ISLocalToGlobalMappingCreateIS(sub_schurs->is_Ej_all,&BtoS);CHKERRQ(ierr);
670     ierr = ISGlobalToLocalMappingApplyIS(BtoS,IS_GTOLM_DROP,change_primal_B,&change_primal_all);CHKERRQ(ierr);
671     ierr = ISLocalToGlobalMappingDestroy(&BtoS);CHKERRQ(ierr);
672     ierr = ISDestroy(&change_primal_B);CHKERRQ(ierr);
673     ierr = PetscMalloc1(sub_schurs->n_subs,&sub_schurs->change);CHKERRQ(ierr);
674     for (i=0;i<sub_schurs->n_subs;i++) {
675       Mat change_sub;
676 
677       ierr = ISGetLocalSize(sub_schurs->is_subs[i],&subset_size);CHKERRQ(ierr);
678       ierr = KSPCreate(PETSC_COMM_SELF,&sub_schurs->change[i]);CHKERRQ(ierr);
679       ierr = KSPSetType(sub_schurs->change[i],KSPPREONLY);CHKERRQ(ierr);
680       if (!sub_schurs->change_with_qr) {
681         ierr = MatGetSubMatrix(change,sub_schurs->is_subs[i],sub_schurs->is_subs[i],MAT_INITIAL_MATRIX,&change_sub);CHKERRQ(ierr);
682       } else {
683         Mat change_subt;
684         ierr = MatGetSubMatrix(change,sub_schurs->is_subs[i],sub_schurs->is_subs[i],MAT_INITIAL_MATRIX,&change_subt);CHKERRQ(ierr);
685         ierr = MatConvert(change_subt,MATSEQDENSE,MAT_INITIAL_MATRIX,&change_sub);CHKERRQ(ierr);
686         ierr = MatDestroy(&change_subt);CHKERRQ(ierr);
687       }
688       ierr = KSPSetOperators(sub_schurs->change[i],change_sub,change_sub);CHKERRQ(ierr);
689       ierr = MatDestroy(&change_sub);CHKERRQ(ierr);
690       ierr = KSPSetOptionsPrefix(sub_schurs->change[i],sub_schurs->prefix);CHKERRQ(ierr);
691       ierr = KSPAppendOptionsPrefix(sub_schurs->change[i],"sub_schurs_change_");CHKERRQ(ierr);
692     }
693     ierr = ISDestroy(&change_primal_all);CHKERRQ(ierr);
694   }
695 
696   /* Local matrix of all local Schur on subsets (transposed) */
697   if (!sub_schurs->S_Ej_all) {
698     ierr = MatCreate(PETSC_COMM_SELF,&sub_schurs->S_Ej_all);CHKERRQ(ierr);
699     ierr = MatSetSizes(sub_schurs->S_Ej_all,PETSC_DECIDE,PETSC_DECIDE,local_size,local_size);CHKERRQ(ierr);
700     ierr = MatSetType(sub_schurs->S_Ej_all,MATAIJ);CHKERRQ(ierr);
701     ierr = MatSeqAIJSetPreallocation(sub_schurs->S_Ej_all,0,nnz);CHKERRQ(ierr);
702   }
703 
704   /* Compute Schur complements explicitly */
705   F = NULL;
706   if (!sub_schurs->schur_explicit) { /* this code branch is used when MatFactor with Schur complemnent support is not present; it is not very efficient, unless the economic version of the scaling is required */
707     Mat         S_Ej_expl;
708     PetscScalar *work;
709     PetscInt    j,*dummy_idx;
710     PetscBool   Sdense;
711 
712     ierr = PetscMalloc2(max_subset_size,&dummy_idx,max_subset_size*max_subset_size,&work);CHKERRQ(ierr);
713     local_size = 0;
714     for (i=0;i<sub_schurs->n_subs;i++) {
715       IS  is_subset_B;
716       Mat AE_EE,AE_IE,AE_EI,S_Ej;
717 
718       /* subsets in original and boundary numbering */
719       ierr = ISGlobalToLocalMappingApplyIS(sub_schurs->BtoNmap,IS_GTOLM_DROP,sub_schurs->is_subs[i],&is_subset_B);CHKERRQ(ierr);
720       /* EE block */
721       ierr = MatGetSubMatrix(A_BB,is_subset_B,is_subset_B,MAT_INITIAL_MATRIX,&AE_EE);CHKERRQ(ierr);
722       /* IE block */
723       ierr = MatGetSubMatrix(A_IB,is_I,is_subset_B,MAT_INITIAL_MATRIX,&AE_IE);CHKERRQ(ierr);
724       /* EI block */
725       if (sub_schurs->is_hermitian) {
726         ierr = MatCreateTranspose(AE_IE,&AE_EI);CHKERRQ(ierr);
727       } else {
728         ierr = MatGetSubMatrix(A_BI,is_subset_B,is_I,MAT_INITIAL_MATRIX,&AE_EI);CHKERRQ(ierr);
729       }
730       ierr = ISDestroy(&is_subset_B);CHKERRQ(ierr);
731       ierr = MatCreateSchurComplement(AE_II,AE_II,AE_IE,AE_EI,AE_EE,&S_Ej);CHKERRQ(ierr);
732       ierr = MatDestroy(&AE_EE);CHKERRQ(ierr);
733       ierr = MatDestroy(&AE_IE);CHKERRQ(ierr);
734       ierr = MatDestroy(&AE_EI);CHKERRQ(ierr);
735       if (AE_II == A_II) { /* we can reuse the same ksp */
736         KSP ksp;
737         ierr = MatSchurComplementGetKSP(sub_schurs->S,&ksp);CHKERRQ(ierr);
738         ierr = MatSchurComplementSetKSP(S_Ej,ksp);CHKERRQ(ierr);
739       } else { /* build new ksp object which inherits ksp and pc types from the original one */
740         KSP       origksp,schurksp;
741         PC        origpc,schurpc;
742         KSPType   ksp_type;
743         PetscInt  n_internal;
744         PetscBool ispcnone;
745 
746         ierr = MatSchurComplementGetKSP(sub_schurs->S,&origksp);CHKERRQ(ierr);
747         ierr = MatSchurComplementGetKSP(S_Ej,&schurksp);CHKERRQ(ierr);
748         ierr = KSPGetType(origksp,&ksp_type);CHKERRQ(ierr);
749         ierr = KSPSetType(schurksp,ksp_type);CHKERRQ(ierr);
750         ierr = KSPGetPC(schurksp,&schurpc);CHKERRQ(ierr);
751         ierr = KSPGetPC(origksp,&origpc);CHKERRQ(ierr);
752         ierr = PetscObjectTypeCompare((PetscObject)origpc,PCNONE,&ispcnone);CHKERRQ(ierr);
753         if (!ispcnone) {
754           PCType pc_type;
755           ierr = PCGetType(origpc,&pc_type);CHKERRQ(ierr);
756           ierr = PCSetType(schurpc,pc_type);CHKERRQ(ierr);
757         } else {
758           ierr = PCSetType(schurpc,PCLU);CHKERRQ(ierr);
759         }
760         ierr = ISGetSize(is_I,&n_internal);CHKERRQ(ierr);
761         if (n_internal) { /* UMFPACK gives error with 0 sized problems */
762           MatSolverPackage solver=NULL;
763           ierr = PCFactorGetMatSolverPackage(origpc,(const MatSolverPackage*)&solver);CHKERRQ(ierr);
764           if (solver) {
765             ierr = PCFactorSetMatSolverPackage(schurpc,solver);CHKERRQ(ierr);
766           }
767         }
768         ierr = KSPSetUp(schurksp);CHKERRQ(ierr);
769       }
770       ierr = ISGetLocalSize(sub_schurs->is_subs[i],&subset_size);CHKERRQ(ierr);
771       ierr = MatCreateSeqDense(PETSC_COMM_SELF,subset_size,subset_size,work,&S_Ej_expl);CHKERRQ(ierr);
772       ierr = PCBDDCComputeExplicitSchur(S_Ej,sub_schurs->is_hermitian,MAT_REUSE_MATRIX,&S_Ej_expl);CHKERRQ(ierr);
773       ierr = PetscObjectTypeCompare((PetscObject)S_Ej_expl,MATSEQDENSE,&Sdense);CHKERRQ(ierr);
774       if (Sdense) {
775         for (j=0;j<subset_size;j++) {
776           dummy_idx[j]=local_size+j;
777         }
778         ierr = MatSetValues(sub_schurs->S_Ej_all,subset_size,dummy_idx,subset_size,dummy_idx,work,INSERT_VALUES);CHKERRQ(ierr);
779       } else SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Not yet implemented for sparse matrices");
780       ierr = MatDestroy(&S_Ej);CHKERRQ(ierr);
781       ierr = MatDestroy(&S_Ej_expl);CHKERRQ(ierr);
782       local_size += subset_size;
783     }
784     ierr = PetscFree2(dummy_idx,work);CHKERRQ(ierr);
785     /* free */
786     ierr = ISDestroy(&is_I);CHKERRQ(ierr);
787     ierr = MatDestroy(&AE_II);CHKERRQ(ierr);
788     ierr = PetscFree(all_local_idx_N);CHKERRQ(ierr);
789   } else {
790     Mat         A,cs_AIB_mat = NULL,benign_AIIm1_ones_mat = NULL;
791     Vec         Dall = NULL;
792     IS          is_A_all,*is_p_r = NULL;
793     PetscScalar *work,*S_data,*schur_factor,infty = PETSC_MAX_REAL;
794     PetscInt    n,n_I,*dummy_idx,size_schur,size_active_schur,cum,cum2;
795     PetscBool   economic,solver_S,S_lower_triangular = PETSC_FALSE,factor_workaround;
796     char        solver[256];
797 
798     /* get sizes */
799     n_I = 0;
800     if (is_I_layer) {
801       ierr = ISGetLocalSize(is_I_layer,&n_I);CHKERRQ(ierr);
802     }
803     economic = PETSC_FALSE;
804     ierr = ISGetLocalSize(sub_schurs->is_I,&cum);CHKERRQ(ierr);
805     if (cum != n_I) economic = PETSC_TRUE;
806     ierr = MatGetLocalSize(sub_schurs->A,&n,NULL);CHKERRQ(ierr);
807     size_active_schur = local_size;
808 
809     /* import scaling vector (wrong formulation if we have 3D edges) */
810     if (scaling && compute_Stilda) {
811       const PetscScalar *array;
812       PetscScalar       *array2;
813       const PetscInt    *idxs;
814       PetscInt          i;
815 
816       ierr = ISGetIndices(sub_schurs->is_Ej_all,&idxs);CHKERRQ(ierr);
817       ierr = VecCreateSeq(PETSC_COMM_SELF,size_active_schur,&Dall);CHKERRQ(ierr);
818       ierr = VecGetArrayRead(scaling,&array);CHKERRQ(ierr);
819       ierr = VecGetArray(Dall,&array2);CHKERRQ(ierr);
820       for (i=0;i<size_active_schur;i++) array2[i] = array[idxs[i]];
821       ierr = VecRestoreArray(Dall,&array2);CHKERRQ(ierr);
822       ierr = VecRestoreArrayRead(scaling,&array);CHKERRQ(ierr);
823       ierr = ISRestoreIndices(sub_schurs->is_Ej_all,&idxs);CHKERRQ(ierr);
824       deluxe = PETSC_FALSE;
825     }
826 
827     /* size active schurs does not count any dirichlet or vertex dof on the interface */
828     cum = n_I+size_active_schur;
829     if (sub_schurs->is_dir) {
830       const PetscInt* idxs;
831       PetscInt        n_dir;
832 
833       ierr = ISGetLocalSize(sub_schurs->is_dir,&n_dir);CHKERRQ(ierr);
834       ierr = ISGetIndices(sub_schurs->is_dir,&idxs);CHKERRQ(ierr);
835       ierr = PetscMemcpy(all_local_idx_N+cum,idxs,n_dir*sizeof(PetscInt));CHKERRQ(ierr);
836       ierr = ISRestoreIndices(sub_schurs->is_dir,&idxs);CHKERRQ(ierr);
837       cum += n_dir;
838     }
839     factor_workaround = PETSC_FALSE;
840     /* include the primal vertices in the Schur complement */
841     if (exact_schur && sub_schurs->is_vertices && (compute_Stilda || benign_n)) {
842       PetscInt n_v;
843 
844       ierr = ISGetLocalSize(sub_schurs->is_vertices,&n_v);CHKERRQ(ierr);
845       if (n_v) {
846         const PetscInt* idxs;
847 
848         ierr = ISGetIndices(sub_schurs->is_vertices,&idxs);CHKERRQ(ierr);
849         ierr = PetscMemcpy(all_local_idx_N+cum,idxs,n_v*sizeof(PetscInt));CHKERRQ(ierr);
850         ierr = ISRestoreIndices(sub_schurs->is_vertices,&idxs);CHKERRQ(ierr);
851         cum += n_v;
852         factor_workaround = PETSC_TRUE;
853       }
854     }
855     size_schur = cum - n_I;
856     ierr = ISCreateGeneral(PETSC_COMM_SELF,cum,all_local_idx_N,PETSC_OWN_POINTER,&is_A_all);CHKERRQ(ierr);
857     /* get working mat (TODO: factorize without actually permuting)  */
858     if (cum == n) {
859       ierr = ISSetPermutation(is_A_all);CHKERRQ(ierr);
860       ierr = MatPermute(sub_schurs->A,is_A_all,is_A_all,&A);CHKERRQ(ierr);
861     } else {
862       ierr = MatGetSubMatrix(sub_schurs->A,is_A_all,is_A_all,MAT_INITIAL_MATRIX,&A);CHKERRQ(ierr);
863     }
864     ierr = MatSetOptionsPrefix(A,sub_schurs->prefix);CHKERRQ(ierr);
865     ierr = MatAppendOptionsPrefix(A,"sub_schurs_");CHKERRQ(ierr);
866 
867     /* if we actually change the basis for the pressures, LDL^T factors will use a lot of memory
868        n^2 instead of n^1.5 or something. This is a workaround */
869     if (benign_n) {
870       Vec                    v;
871       ISLocalToGlobalMapping N_to_reor;
872       IS                     is_p0,is_p0_p;
873       PetscScalar            *cs_AIB,*AIIm1_data;
874       PetscInt               sizeA;
875 
876       ierr = ISLocalToGlobalMappingCreateIS(is_A_all,&N_to_reor);CHKERRQ(ierr);
877       ierr = ISCreateGeneral(PETSC_COMM_SELF,benign_n,benign_p0_lidx,PETSC_COPY_VALUES,&is_p0);CHKERRQ(ierr);
878       ierr = ISGlobalToLocalMappingApplyIS(N_to_reor,IS_GTOLM_DROP,is_p0,&is_p0_p);CHKERRQ(ierr);
879       ierr = ISDestroy(&is_p0);CHKERRQ(ierr);
880       ierr = MatCreateVecs(A,&v,NULL);CHKERRQ(ierr);
881       ierr = VecGetSize(v,&sizeA);CHKERRQ(ierr);
882       ierr = MatCreateSeqDense(PETSC_COMM_SELF,sizeA,benign_n,NULL,&benign_AIIm1_ones_mat);CHKERRQ(ierr);
883       ierr = MatCreateSeqDense(PETSC_COMM_SELF,size_schur,benign_n,NULL,&cs_AIB_mat);CHKERRQ(ierr);
884       ierr = MatDenseGetArray(cs_AIB_mat,&cs_AIB);CHKERRQ(ierr);
885       ierr = MatDenseGetArray(benign_AIIm1_ones_mat,&AIIm1_data);CHKERRQ(ierr);
886       ierr = PetscMalloc1(benign_n,&is_p_r);CHKERRQ(ierr);
887       /* compute colsum of A_IB restricted to pressures */
888       for (i=0;i<benign_n;i++) {
889         Vec            benign_AIIm1_ones;
890         PetscScalar    *array;
891         const PetscInt *idxs;
892         PetscInt       j,nz;
893 
894         ierr = ISGlobalToLocalMappingApplyIS(N_to_reor,IS_GTOLM_DROP,benign_zerodiag_subs[i],&is_p_r[i]);CHKERRQ(ierr);
895         ierr = ISGetLocalSize(is_p_r[i],&nz);CHKERRQ(ierr);
896         ierr = ISGetIndices(is_p_r[i],&idxs);CHKERRQ(ierr);
897         for (j=0;j<nz;j++) AIIm1_data[idxs[j]+sizeA*i] = 1.;
898         ierr = ISRestoreIndices(is_p_r[i],&idxs);CHKERRQ(ierr);
899         ierr = VecCreateSeqWithArray(PETSC_COMM_SELF,1,sizeA,AIIm1_data+sizeA*i,&benign_AIIm1_ones);CHKERRQ(ierr);
900         ierr = MatMult(A,benign_AIIm1_ones,v);CHKERRQ(ierr);
901         ierr = VecDestroy(&benign_AIIm1_ones);CHKERRQ(ierr);
902         ierr = VecGetArray(v,&array);CHKERRQ(ierr);
903         for (j=0;j<size_schur;j++) {
904 #if defined(PETSC_USE_COMPLEX)
905           cs_AIB[i*size_schur + j] = (PetscRealPart(array[j+n_I])/nz + PETSC_i*(PetscImaginaryPart(array[j+n_I])/nz));
906 #else
907           cs_AIB[i*size_schur + j] = array[j+n_I]/nz;
908 #endif
909         }
910         ierr = VecRestoreArray(v,&array);CHKERRQ(ierr);
911       }
912       ierr = MatDenseRestoreArray(cs_AIB_mat,&cs_AIB);CHKERRQ(ierr);
913       ierr = MatDenseRestoreArray(benign_AIIm1_ones_mat,&AIIm1_data);CHKERRQ(ierr);
914       ierr = VecDestroy(&v);CHKERRQ(ierr);
915       ierr = MatSetOption(A,MAT_KEEP_NONZERO_PATTERN,PETSC_FALSE);CHKERRQ(ierr);
916       ierr = MatSetOption(A,MAT_NEW_NONZERO_LOCATION_ERR,PETSC_FALSE);CHKERRQ(ierr);
917       ierr = MatSetOption(A,MAT_NEW_NONZERO_ALLOCATION_ERR,PETSC_FALSE);CHKERRQ(ierr);
918       ierr = MatZeroRowsColumnsIS(A,is_p0_p,1.0,NULL,NULL);CHKERRQ(ierr);
919       ierr = ISDestroy(&is_p0_p);CHKERRQ(ierr);
920       ierr = ISLocalToGlobalMappingDestroy(&N_to_reor);CHKERRQ(ierr);
921     }
922     ierr = MatSetOption(A,MAT_SYMMETRIC,sub_schurs->is_hermitian);CHKERRQ(ierr);
923     ierr = MatSetOption(A,MAT_HERMITIAN,sub_schurs->is_hermitian);CHKERRQ(ierr);
924     ierr = MatSetOption(A,MAT_SPD,sub_schurs->is_posdef);CHKERRQ(ierr);
925 #if defined(PETSC_HAVE_MUMPS)
926     ierr = PetscStrcpy(solver,MATSOLVERMUMPS);CHKERRQ(ierr);
927 #else
928     ierr = PetscStrcpy(solver,MATSOLVERMKL_PARDISO);CHKERRQ(ierr);
929 #endif
930     ierr = PetscOptionsGetString(NULL,((PetscObject)A)->prefix,"-mat_solver_package",solver,256,NULL);CHKERRQ(ierr);
931 
932     /* when using the benign subspace trick, the local Schur complements are SPD */
933     if (benign_trick) sub_schurs->is_posdef = PETSC_TRUE;
934 
935     if (n_I) { /* TODO add ordering from options */
936       IS is_schur;
937 
938       if (sub_schurs->is_hermitian && sub_schurs->is_posdef) {
939         ierr = MatGetFactor(A,solver,MAT_FACTOR_CHOLESKY,&F);CHKERRQ(ierr);
940       } else {
941         ierr = MatGetFactor(A,solver,MAT_FACTOR_LU,&F);CHKERRQ(ierr);
942       }
943       ierr = MatSetErrorIfFailure(A,PETSC_TRUE);CHKERRQ(ierr);
944 
945       /* subsets ordered last */
946       ierr = ISCreateStride(PETSC_COMM_SELF,size_schur,n_I,1,&is_schur);CHKERRQ(ierr);
947       ierr = MatFactorSetSchurIS(F,is_schur);CHKERRQ(ierr);
948       ierr = ISDestroy(&is_schur);CHKERRQ(ierr);
949 
950       /* factorization step */
951       if (sub_schurs->is_hermitian && sub_schurs->is_posdef) {
952         ierr = MatCholeskyFactorSymbolic(F,A,NULL,NULL);CHKERRQ(ierr);
953 #if defined(PETSC_HAVE_MUMPS) /* be sure that icntl 19 is not set by command line */
954         ierr = MatMumpsSetIcntl(F,19,2);CHKERRQ(ierr);
955 #endif
956         if (sub_schurs->is_posdef) {
957           ierr = MatFactorSetSchurComplementSolverType(F,1);CHKERRQ(ierr);
958         } else {
959           ierr = MatFactorSetSchurComplementSolverType(F,2);CHKERRQ(ierr);
960         }
961         ierr = MatCholeskyFactorNumeric(F,A,NULL);CHKERRQ(ierr);
962         S_lower_triangular = PETSC_TRUE;
963       } else {
964         ierr = MatLUFactorSymbolic(F,A,NULL,NULL,NULL);CHKERRQ(ierr);
965 #if defined(PETSC_HAVE_MUMPS) /* be sure that icntl 19 is not set by command line */
966         ierr = MatMumpsSetIcntl(F,19,3);CHKERRQ(ierr);
967 #endif
968         ierr = MatLUFactorNumeric(F,A,NULL);CHKERRQ(ierr);
969       }
970       ierr = MatViewFromOptions(F,(PetscObject)A,"-mat_factor_view");CHKERRQ(ierr);
971 
972       /* get explicit Schur Complement computed during numeric factorization */
973       ierr = MatFactorGetSchurComplement(F,&S_all);CHKERRQ(ierr);
974       /* we can reuse the solvers if we are not using the economic version */
975       reuse_solvers = (PetscBool)(reuse_solvers && !economic);
976       factor_workaround = (PetscBool)(reuse_solvers && factor_workaround);
977       solver_S = PETSC_TRUE;
978 
979       /* update the Schur complement with the change of basis on the pressures */
980       if (benign_n) {
981         PetscScalar *S_data,*cs_AIB,*AIIm1_data;
982         Vec         v;
983         PetscInt    sizeA;
984 
985         ierr = MatDenseGetArray(S_all,&S_data);CHKERRQ(ierr);
986         ierr = MatCreateVecs(A,&v,NULL);CHKERRQ(ierr);
987         ierr = VecGetSize(v,&sizeA);CHKERRQ(ierr);
988 #if defined(PETSC_HAVE_MUMPS)
989         ierr = MatMumpsSetIcntl(F,26,0);CHKERRQ(ierr);
990 #endif
991 #if defined(PETSC_HAVE_MKL_PARDISO)
992         ierr = MatMkl_PardisoSetCntl(F,70,1);CHKERRQ(ierr);
993 #endif
994         ierr = MatDenseGetArray(cs_AIB_mat,&cs_AIB);CHKERRQ(ierr);
995         ierr = MatDenseGetArray(benign_AIIm1_ones_mat,&AIIm1_data);CHKERRQ(ierr);
996         for (i=0;i<benign_n;i++) {
997           Vec            benign_AIIm1_ones;
998           PetscScalar    *array,sum = 0.,one = 1.;
999           const PetscInt *idxs;
1000           PetscInt       j,nz;
1001           PetscBLASInt   B_k,B_n;
1002 
1003           ierr = VecCreateSeqWithArray(PETSC_COMM_SELF,1,sizeA,AIIm1_data+sizeA*i,&benign_AIIm1_ones);CHKERRQ(ierr);
1004           ierr = VecCopy(benign_AIIm1_ones,v);CHKERRQ(ierr);
1005           ierr = MatSolve(F,v,benign_AIIm1_ones);CHKERRQ(ierr);
1006           ierr = ISGetLocalSize(is_p_r[i],&nz);CHKERRQ(ierr);
1007           ierr = ISGetIndices(is_p_r[i],&idxs);CHKERRQ(ierr);
1008           /* p0 dof (eliminated) is excluded from the sum */
1009           for (j=0;j<nz-1;j++) sum -= AIIm1_data[idxs[j]+sizeA*i];
1010           ierr = ISRestoreIndices(is_p_r[i],&idxs);CHKERRQ(ierr);
1011           ierr = MatMult(A,benign_AIIm1_ones,v);CHKERRQ(ierr);
1012           ierr = VecGetArray(v,&array);CHKERRQ(ierr);
1013           /* perform sparse rank updates on symmetric Schur (TODO: move outside of the loop?) */
1014           /* cs_AIB already scaled by 1./nz */
1015           B_k = 1;
1016           ierr = PetscBLASIntCast(size_schur,&B_n);CHKERRQ(ierr);
1017           PetscStackCallBLAS("BLASsyrk",BLASsyrk_("L","N",&B_n,&B_k,&sum,cs_AIB+i*size_schur,&B_n,&one,S_data,&B_n));
1018           sum  = 1.;
1019           PetscStackCallBLAS("BLASsyr2k",BLASsyr2k_("L","N",&B_n,&B_k,&sum,array+n_I,&B_n,cs_AIB+i*size_schur,&B_n,&one,S_data,&B_n));
1020           ierr = VecRestoreArray(v,&array);CHKERRQ(ierr);
1021           /* set p0 entry of AIIm1_ones to zero */
1022           ierr = ISGetIndices(is_p_r[i],&idxs);CHKERRQ(ierr);
1023           for (j=0;j<benign_n;j++) AIIm1_data[idxs[nz-1]+sizeA*j] = 0.;
1024           ierr = ISRestoreIndices(is_p_r[i],&idxs);CHKERRQ(ierr);
1025           ierr = VecDestroy(&benign_AIIm1_ones);CHKERRQ(ierr);
1026         }
1027   /* restore defaults */
1028 #if defined(PETSC_HAVE_MUMPS)
1029         ierr = MatMumpsSetIcntl(F,26,-1);CHKERRQ(ierr);
1030 #endif
1031 #if defined(PETSC_HAVE_MKL_PARDISO)
1032         ierr = MatMkl_PardisoSetCntl(F,70,0);CHKERRQ(ierr);
1033 #endif
1034         ierr = MatDenseRestoreArray(cs_AIB_mat,&cs_AIB);CHKERRQ(ierr);
1035         ierr = MatDenseRestoreArray(benign_AIIm1_ones_mat,&AIIm1_data);CHKERRQ(ierr);
1036         ierr = VecDestroy(&v);CHKERRQ(ierr);
1037         ierr = MatDenseRestoreArray(S_all,&S_data);CHKERRQ(ierr);
1038       }
1039       if (!reuse_solvers) {
1040         for (i=0;i<benign_n;i++) {
1041           ierr = ISDestroy(&is_p_r[i]);CHKERRQ(ierr);
1042         }
1043         ierr = PetscFree(is_p_r);CHKERRQ(ierr);
1044         ierr = MatDestroy(&cs_AIB_mat);CHKERRQ(ierr);
1045         ierr = MatDestroy(&benign_AIIm1_ones_mat);CHKERRQ(ierr);
1046       }
1047     } else { /* we can't use MatFactor when size_schur == size_of_the_problem */
1048       ierr = MatConvert(A,MATSEQDENSE,MAT_INITIAL_MATRIX,&S_all);CHKERRQ(ierr);
1049       reuse_solvers = PETSC_FALSE; /* TODO: why we can't reuse the solvers here? */
1050       factor_workaround = PETSC_FALSE;
1051       solver_S = PETSC_FALSE;
1052     }
1053 
1054     if (reuse_solvers) {
1055       Mat                A_II,Afake;
1056       Vec                vec1_B;
1057       PCBDDCReuseSolvers msolv_ctx;
1058       PetscInt           n_R;
1059 
1060       if (sub_schurs->reuse_solver) {
1061         ierr = PCBDDCReuseSolversReset(sub_schurs->reuse_solver);CHKERRQ(ierr);
1062       } else {
1063         ierr = PetscNew(&sub_schurs->reuse_solver);CHKERRQ(ierr);
1064       }
1065       msolv_ctx = sub_schurs->reuse_solver;
1066       ierr = MatSchurComplementGetSubMatrices(sub_schurs->S,&A_II,NULL,NULL,NULL,NULL);CHKERRQ(ierr);
1067       ierr = PetscObjectReference((PetscObject)F);CHKERRQ(ierr);
1068       msolv_ctx->F = F;
1069       ierr = MatCreateVecs(F,&msolv_ctx->sol,NULL);CHKERRQ(ierr);
1070       /* currently PETSc has no support for MatSolve(F,x,x), so cheat and let rhs and sol share the same memory */
1071       {
1072         PetscScalar *array;
1073         PetscInt    n;
1074 
1075         ierr = VecGetLocalSize(msolv_ctx->sol,&n);CHKERRQ(ierr);
1076         ierr = VecGetArray(msolv_ctx->sol,&array);CHKERRQ(ierr);
1077         ierr = VecCreateSeqWithArray(PetscObjectComm((PetscObject)msolv_ctx->sol),1,n,array,&msolv_ctx->rhs);CHKERRQ(ierr);
1078         ierr = VecRestoreArray(msolv_ctx->sol,&array);CHKERRQ(ierr);
1079       }
1080       msolv_ctx->has_vertices = factor_workaround;
1081 
1082       /* interior solver */
1083       ierr = PCCreate(PetscObjectComm((PetscObject)A_II),&msolv_ctx->interior_solver);CHKERRQ(ierr);
1084       ierr = PCSetOperators(msolv_ctx->interior_solver,A_II,A_II);CHKERRQ(ierr);
1085       ierr = PCSetType(msolv_ctx->interior_solver,PCSHELL);CHKERRQ(ierr);
1086       ierr = PCShellSetContext(msolv_ctx->interior_solver,msolv_ctx);CHKERRQ(ierr);
1087       ierr = PCShellSetApply(msolv_ctx->interior_solver,PCBDDCReuseSolvers_Interior);CHKERRQ(ierr);
1088       ierr = PCShellSetApplyTranspose(msolv_ctx->interior_solver,PCBDDCReuseSolvers_InteriorTranspose);CHKERRQ(ierr);
1089 
1090       /* correction solver */
1091       ierr = PCCreate(PetscObjectComm((PetscObject)A_II),&msolv_ctx->correction_solver);CHKERRQ(ierr);
1092       ierr = PCSetType(msolv_ctx->correction_solver,PCSHELL);CHKERRQ(ierr);
1093       ierr = PCShellSetContext(msolv_ctx->correction_solver,msolv_ctx);CHKERRQ(ierr);
1094       ierr = PCShellSetApply(msolv_ctx->correction_solver,PCBDDCReuseSolvers_Correction);CHKERRQ(ierr);
1095       ierr = PCShellSetApplyTranspose(msolv_ctx->correction_solver,PCBDDCReuseSolvers_CorrectionTranspose);CHKERRQ(ierr);
1096 
1097       /* scatter and vecs for Schur complement solver */
1098       ierr = MatCreateVecs(S_all,&msolv_ctx->sol_B,&msolv_ctx->rhs_B);CHKERRQ(ierr);
1099       ierr = MatCreateVecs(sub_schurs->S,&vec1_B,NULL);CHKERRQ(ierr);
1100       if (!factor_workaround) {
1101         ierr = ISGlobalToLocalMappingApplyIS(sub_schurs->BtoNmap,IS_GTOLM_DROP,is_A_all,&msolv_ctx->is_B);CHKERRQ(ierr);
1102         ierr = VecScatterCreate(vec1_B,msolv_ctx->is_B,msolv_ctx->sol_B,NULL,&msolv_ctx->correction_scatter_B);CHKERRQ(ierr);
1103         ierr = PetscObjectReference((PetscObject)is_A_all);CHKERRQ(ierr);
1104         msolv_ctx->is_R = is_A_all;
1105       } else {
1106         IS              is_B_all;
1107         const PetscInt* idxs;
1108         PetscInt        dual,n_v,n;
1109 
1110         ierr = ISGetLocalSize(sub_schurs->is_vertices,&n_v);CHKERRQ(ierr);
1111         dual = size_schur - n_v;
1112         ierr = ISGetLocalSize(is_A_all,&n);CHKERRQ(ierr);
1113         ierr = ISGetIndices(is_A_all,&idxs);CHKERRQ(ierr);
1114         ierr = ISCreateGeneral(PetscObjectComm((PetscObject)is_A_all),dual,idxs+n_I,PETSC_COPY_VALUES,&is_B_all);CHKERRQ(ierr);
1115         ierr = ISGlobalToLocalMappingApplyIS(sub_schurs->BtoNmap,IS_GTOLM_DROP,is_B_all,&msolv_ctx->is_B);CHKERRQ(ierr);
1116         ierr = ISDestroy(&is_B_all);CHKERRQ(ierr);
1117         ierr = ISCreateStride(PetscObjectComm((PetscObject)is_A_all),dual,0,1,&is_B_all);CHKERRQ(ierr);
1118         ierr = VecScatterCreate(vec1_B,msolv_ctx->is_B,msolv_ctx->sol_B,is_B_all,&msolv_ctx->correction_scatter_B);CHKERRQ(ierr);
1119         ierr = ISDestroy(&is_B_all);CHKERRQ(ierr);
1120         ierr = ISCreateGeneral(PetscObjectComm((PetscObject)is_A_all),n-n_v,idxs,PETSC_COPY_VALUES,&msolv_ctx->is_R);CHKERRQ(ierr);
1121         ierr = ISRestoreIndices(is_A_all,&idxs);CHKERRQ(ierr);
1122       }
1123       ierr = ISGetLocalSize(msolv_ctx->is_R,&n_R);CHKERRQ(ierr);
1124       ierr = MatCreateSeqAIJ(PETSC_COMM_SELF,n_R,n_R,0,NULL,&Afake);CHKERRQ(ierr);
1125       ierr = PCSetOperators(msolv_ctx->correction_solver,Afake,Afake);CHKERRQ(ierr);
1126       ierr = MatDestroy(&Afake);CHKERRQ(ierr);
1127       ierr = VecDestroy(&vec1_B);CHKERRQ(ierr);
1128 
1129       /* communicate benign info to solver context */
1130       if (benign_n) {
1131         PetscScalar *array;
1132 
1133         msolv_ctx->benign_n = benign_n;
1134         msolv_ctx->benign_zerodiag_subs = is_p_r;
1135         ierr = PetscMalloc1(benign_n,&msolv_ctx->benign_save_vals);CHKERRQ(ierr);
1136         msolv_ctx->benign_csAIB = cs_AIB_mat;
1137         ierr = MatCreateVecs(cs_AIB_mat,&msolv_ctx->benign_corr_work,NULL);CHKERRQ(ierr);
1138         ierr = VecGetArray(msolv_ctx->benign_corr_work,&array);CHKERRQ(ierr);
1139         ierr = VecCreateSeqWithArray(PETSC_COMM_SELF,1,size_schur,array,&msolv_ctx->benign_dummy_schur_vec);CHKERRQ(ierr);
1140         ierr = VecRestoreArray(msolv_ctx->benign_corr_work,&array);CHKERRQ(ierr);
1141         msolv_ctx->benign_AIIm1ones = benign_AIIm1_ones_mat;
1142       }
1143     }
1144     ierr = MatDestroy(&A);CHKERRQ(ierr);
1145     ierr = ISDestroy(&is_A_all);CHKERRQ(ierr);
1146 
1147     /* Work arrays */
1148     ierr = PetscMalloc2(max_subset_size,&dummy_idx,max_subset_size*max_subset_size,&work);CHKERRQ(ierr);
1149 
1150     /* matrices for adaptive selection */
1151     if (compute_Stilda) {
1152       if (!sub_schurs->sum_S_Ej_tilda_all) {
1153         ierr = MatCreate(PETSC_COMM_SELF,&sub_schurs->sum_S_Ej_tilda_all);CHKERRQ(ierr);
1154         ierr = MatSetSizes(sub_schurs->sum_S_Ej_tilda_all,PETSC_DECIDE,PETSC_DECIDE,size_active_schur,size_active_schur);CHKERRQ(ierr);
1155         ierr = MatSetType(sub_schurs->sum_S_Ej_tilda_all,MATAIJ);CHKERRQ(ierr);
1156         ierr = MatSeqAIJSetPreallocation(sub_schurs->sum_S_Ej_tilda_all,0,nnz);CHKERRQ(ierr);
1157       }
1158       if (!sub_schurs->sum_S_Ej_inv_all && deluxe) {
1159         ierr = MatCreate(PETSC_COMM_SELF,&sub_schurs->sum_S_Ej_inv_all);CHKERRQ(ierr);
1160         ierr = MatSetSizes(sub_schurs->sum_S_Ej_inv_all,PETSC_DECIDE,PETSC_DECIDE,size_active_schur,size_active_schur);CHKERRQ(ierr);
1161         ierr = MatSetType(sub_schurs->sum_S_Ej_inv_all,MATAIJ);CHKERRQ(ierr);
1162         ierr = MatSeqAIJSetPreallocation(sub_schurs->sum_S_Ej_inv_all,0,nnz);CHKERRQ(ierr);
1163       }
1164     }
1165 
1166     /* S_Ej_all */
1167     cum = cum2 = 0;
1168     ierr = MatDenseGetArray(S_all,&S_data);CHKERRQ(ierr);
1169     for (i=0;i<sub_schurs->n_subs;i++) {
1170       PetscInt j;
1171 
1172       /* get S_E */
1173       ierr = ISGetLocalSize(sub_schurs->is_subs[i],&subset_size);CHKERRQ(ierr);
1174       if (S_lower_triangular) { /* I need to expand the upper triangular data (column oriented) */
1175         PetscInt k;
1176         for (k=0;k<subset_size;k++) {
1177           for (j=k;j<subset_size;j++) {
1178             work[k*subset_size+j] = S_data[cum2+k*size_schur+j];
1179             work[j*subset_size+k] = PetscConj(S_data[cum2+k*size_schur+j]);
1180           }
1181         }
1182       } else { /* just copy to workspace */
1183         PetscInt k;
1184         for (k=0;k<subset_size;k++) {
1185           for (j=0;j<subset_size;j++) {
1186             work[k*subset_size+j] = S_data[cum2+k*size_schur+j];
1187           }
1188         }
1189       }
1190       /* insert S_E values */
1191       for (j=0;j<subset_size;j++) dummy_idx[j] = cum+j;
1192       if (sub_schurs->change) {
1193         Mat            change_sub,SEj,T;
1194 
1195         /* change basis */
1196         ierr = KSPGetOperators(sub_schurs->change[i],&change_sub,NULL);CHKERRQ(ierr);
1197         ierr = MatCreateSeqDense(PETSC_COMM_SELF,subset_size,subset_size,work,&SEj);CHKERRQ(ierr);
1198         if (!sub_schurs->change_with_qr) { /* currently there's no support for PtAP with P SeqAIJ */
1199           Mat T2;
1200           ierr = MatTransposeMatMult(change_sub,SEj,MAT_INITIAL_MATRIX,1.0,&T2);CHKERRQ(ierr);
1201           ierr = MatMatMult(T2,change_sub,MAT_INITIAL_MATRIX,1.0,&T);CHKERRQ(ierr);
1202           ierr = MatConvert(T,MATSEQDENSE,MAT_INPLACE_MATRIX,&T);CHKERRQ(ierr);
1203           ierr = MatDestroy(&T2);CHKERRQ(ierr);
1204         } else {
1205           ierr = MatPtAP(SEj,change_sub,MAT_INITIAL_MATRIX,1.0,&T);CHKERRQ(ierr);
1206         }
1207         ierr = MatCopy(T,SEj,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
1208         ierr = MatDestroy(&T);CHKERRQ(ierr);
1209         ierr = MatZeroRowsColumnsIS(SEj,sub_schurs->change_primal_sub[i],1.0,NULL,NULL);CHKERRQ(ierr);
1210         ierr = MatDestroy(&SEj);CHKERRQ(ierr);
1211       }
1212       if (deluxe) {
1213         ierr = MatSetValues(sub_schurs->S_Ej_all,subset_size,dummy_idx,subset_size,dummy_idx,work,INSERT_VALUES);CHKERRQ(ierr);
1214         /* if adaptivity is requested, invert S_E blocks */
1215         if (compute_Stilda) {
1216           ierr = PetscBLASIntCast(subset_size,&B_N);CHKERRQ(ierr);
1217           ierr = PetscFPTrapPush(PETSC_FP_TRAP_OFF);CHKERRQ(ierr);
1218           if (!use_getr) { /* TODO add sytrf/i for symmetric non hermitian */
1219             PetscInt k;
1220             PetscStackCallBLAS("LAPACKpotrf",LAPACKpotrf_("L",&B_N,work,&B_N,&B_ierr));
1221             if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in POTRF Lapack routine %d",(int)B_ierr);
1222             PetscStackCallBLAS("LAPACKpotri",LAPACKpotri_("L",&B_N,work,&B_N,&B_ierr));
1223             if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in POTRI Lapack routine %d",(int)B_ierr);
1224             for (k=0;k<subset_size;k++) {
1225               for (j=k;j<subset_size;j++) {
1226                 work[j*subset_size+k] = work[k*subset_size+j];
1227               }
1228             }
1229           } else {
1230             PetscStackCallBLAS("LAPACKgetrf",LAPACKgetrf_(&B_N,&B_N,work,&B_N,pivots,&B_ierr));
1231             if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in GETRF Lapack routine %d",(int)B_ierr);
1232             PetscStackCallBLAS("LAPACKgetri",LAPACKgetri_(&B_N,work,&B_N,pivots,Bwork,&B_lwork,&B_ierr));
1233             if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in GETRI Lapack routine %d",(int)B_ierr);
1234           }
1235           ierr = PetscFPTrapPop();CHKERRQ(ierr);
1236           ierr = MatSetValues(sub_schurs->sum_S_Ej_inv_all,subset_size,dummy_idx,subset_size,dummy_idx,work,INSERT_VALUES);CHKERRQ(ierr);
1237         }
1238       } else if (compute_Stilda) { /* not using deluxe */
1239         Mat         SEj;
1240         Vec         D;
1241         PetscScalar *array;
1242 
1243         ierr = MatCreateSeqDense(PETSC_COMM_SELF,subset_size,subset_size,work,&SEj);CHKERRQ(ierr);
1244         ierr = VecGetArray(Dall,&array);CHKERRQ(ierr);
1245         ierr = VecCreateSeqWithArray(PETSC_COMM_SELF,1,subset_size,array+cum,&D);CHKERRQ(ierr);
1246         ierr = VecRestoreArray(Dall,&array);CHKERRQ(ierr);
1247         ierr = VecShift(D,-1.);CHKERRQ(ierr);
1248         ierr = MatDiagonalScale(SEj,D,D);CHKERRQ(ierr);
1249         ierr = MatDestroy(&SEj);CHKERRQ(ierr);
1250         ierr = VecDestroy(&D);CHKERRQ(ierr);
1251         ierr = MatSetValues(sub_schurs->S_Ej_all,subset_size,dummy_idx,subset_size,dummy_idx,work,INSERT_VALUES);CHKERRQ(ierr);
1252       }
1253       cum += subset_size;
1254       cum2 += subset_size*(size_schur + 1);
1255     }
1256     ierr = MatDenseRestoreArray(S_all,&S_data);CHKERRQ(ierr);
1257 
1258     if (solver_S) {
1259       ierr = MatFactorRestoreSchurComplement(F,&S_all);CHKERRQ(ierr);
1260     }
1261 
1262     schur_factor = NULL;
1263     if (compute_Stilda && size_active_schur) {
1264 
1265       if (sub_schurs->n_subs == 1 && size_schur == size_active_schur && deluxe) { /* we already computed the inverse */
1266         PetscInt j;
1267         for (j=0;j<size_schur;j++) dummy_idx[j] = j;
1268         ierr = MatSetValues(sub_schurs->sum_S_Ej_tilda_all,size_schur,dummy_idx,size_schur,dummy_idx,work,INSERT_VALUES);CHKERRQ(ierr);
1269       } else {
1270         Mat S_all_inv=NULL;
1271         if (solver_S) { /* use MatFactor calls to invert S */
1272             /* let MatFactor factor the Schur complement */
1273           ierr = MatFactorFactorizeSchurComplement(F);CHKERRQ(ierr);
1274           /* for adaptive selection we need S^-1; for solver reusage we need S_\Delta\Delta^-1.
1275              The latter is not the principal subminor for S^-1. However, the factors can be reused since S_\Delta\Delta is the leading principal submatrix of S */
1276           if (factor_workaround) {
1277             PetscScalar *data;
1278             PetscInt nd = 0;
1279 
1280             if (!sub_schurs->is_posdef) {
1281               SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Factor update not yet implemented for non SPD matrices");
1282             }
1283             ierr = MatFactorGetSchurComplement(F,&S_all_inv);CHKERRQ(ierr);
1284             ierr = MatDenseGetArray(S_all_inv,&data);CHKERRQ(ierr);
1285             if (sub_schurs->is_dir) { /* dirichlet dofs could have different scalings */
1286               ierr = ISGetLocalSize(sub_schurs->is_dir,&nd);CHKERRQ(ierr);
1287             }
1288             ierr = PetscMalloc1((size_active_schur*(size_active_schur+1))/2+nd,&schur_factor);CHKERRQ(ierr);
1289             cum = 0;
1290             for (i=0;i<size_active_schur;i++) {
1291               ierr = PetscMemcpy(schur_factor+cum,data+i*(size_schur+1),(size_active_schur-i)*sizeof(PetscScalar));CHKERRQ(ierr);
1292               cum += size_active_schur-i;
1293             }
1294             for (i=0;i<nd;i++) schur_factor[cum+i] = data[(i+size_active_schur)*(size_schur+1)];
1295             /* invert without calling MatFactorInvertSchurComplement, since we are hacking */
1296             ierr = PetscBLASIntCast(size_schur,&B_N);CHKERRQ(ierr);
1297             ierr = PetscFPTrapPush(PETSC_FP_TRAP_OFF);CHKERRQ(ierr);
1298             PetscStackCallBLAS("LAPACKpotri",LAPACKpotri_("L",&B_N,data,&B_N,&B_ierr));
1299             ierr = PetscFPTrapPop();CHKERRQ(ierr);
1300             if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in POTRI Lapack routine %d",(int)B_ierr);
1301             ierr = MatDenseRestoreArray(S_all_inv,&data);CHKERRQ(ierr);
1302           } else {
1303             ierr = MatFactorInvertSchurComplement(F);CHKERRQ(ierr);
1304             ierr = MatFactorGetSchurComplement(F,&S_all_inv);CHKERRQ(ierr);
1305           }
1306         } else { /* we need to invert explicitly since we are not using MatFactor for S */
1307           ierr = PetscObjectReference((PetscObject)S_all);CHKERRQ(ierr);
1308           S_all_inv = S_all;
1309           ierr = MatDenseGetArray(S_all_inv,&S_data);CHKERRQ(ierr);
1310           ierr = PetscBLASIntCast(size_schur,&B_N);CHKERRQ(ierr);
1311           ierr = PetscFPTrapPush(PETSC_FP_TRAP_OFF);CHKERRQ(ierr);
1312           if (!use_getr) { /* TODO add sytrf/i for symmetric non hermitian */
1313             PetscStackCallBLAS("LAPACKpotrf",LAPACKpotrf_("L",&B_N,S_data,&B_N,&B_ierr));
1314             if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in POTRF Lapack routine %d",(int)B_ierr);
1315             PetscStackCallBLAS("LAPACKpotri",LAPACKpotri_("L",&B_N,S_data,&B_N,&B_ierr));
1316             if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in POTRI Lapack routine %d",(int)B_ierr);
1317           } else {
1318             PetscStackCallBLAS("LAPACKgetrf",LAPACKgetrf_(&B_N,&B_N,S_data,&B_N,pivots,&B_ierr));
1319             if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in GETRF Lapack routine %d",(int)B_ierr);
1320             PetscStackCallBLAS("LAPACKgetri",LAPACKgetri_(&B_N,S_data,&B_N,pivots,Bwork,&B_lwork,&B_ierr));
1321             if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in GETRI Lapack routine %d",(int)B_ierr);
1322           }
1323           ierr = PetscFPTrapPop();CHKERRQ(ierr);
1324           ierr = MatDenseRestoreArray(S_all_inv,&S_data);CHKERRQ(ierr);
1325         }
1326         /* S_Ej_tilda_all */
1327         cum = cum2 = 0;
1328         ierr = MatDenseGetArray(S_all_inv,&S_data);CHKERRQ(ierr);
1329         for (i=0;i<sub_schurs->n_subs;i++) {
1330           PetscInt j;
1331 
1332           ierr = ISGetLocalSize(sub_schurs->is_subs[i],&subset_size);CHKERRQ(ierr);
1333           /* get (St^-1)_E */
1334           /* Unless we are changing the variables, I don't need to expand to upper triangular since St^-1
1335              will be properly accessed later during adaptive selection */
1336           if (S_lower_triangular) {
1337             PetscInt k;
1338             if (sub_schurs->change) {
1339               for (k=0;k<subset_size;k++) {
1340                 for (j=k;j<subset_size;j++) {
1341                   work[k*subset_size+j] = S_data[cum2+k*size_schur+j];
1342                   work[j*subset_size+k] = work[k*subset_size+j];
1343                 }
1344               }
1345             } else {
1346               for (k=0;k<subset_size;k++) {
1347                 for (j=k;j<subset_size;j++) {
1348                   work[k*subset_size+j] = S_data[cum2+k*size_schur+j];
1349                 }
1350               }
1351             }
1352           } else {
1353             PetscInt k;
1354             for (k=0;k<subset_size;k++) {
1355               for (j=0;j<subset_size;j++) {
1356                 work[k*subset_size+j] = S_data[cum2+k*size_schur+j];
1357               }
1358             }
1359           }
1360           if (sub_schurs->change) {
1361             Mat change_sub,SEj,T;
1362 
1363             /* change basis */
1364             ierr = KSPGetOperators(sub_schurs->change[i],&change_sub,NULL);CHKERRQ(ierr);
1365             ierr = MatCreateSeqDense(PETSC_COMM_SELF,subset_size,subset_size,work,&SEj);CHKERRQ(ierr);
1366             if (!sub_schurs->change_with_qr) { /* currently there's no support for PtAP with P SeqAIJ */
1367               Mat T2;
1368               ierr = MatTransposeMatMult(change_sub,SEj,MAT_INITIAL_MATRIX,1.0,&T2);CHKERRQ(ierr);
1369               ierr = MatMatMult(T2,change_sub,MAT_INITIAL_MATRIX,1.0,&T);CHKERRQ(ierr);
1370               ierr = MatDestroy(&T2);CHKERRQ(ierr);
1371               ierr = MatConvert(T,MATSEQDENSE,MAT_INPLACE_MATRIX,&T);CHKERRQ(ierr);
1372             } else {
1373               ierr = MatPtAP(SEj,change_sub,MAT_INITIAL_MATRIX,1.0,&T);CHKERRQ(ierr);
1374             }
1375             ierr = MatCopy(T,SEj,SAME_NONZERO_PATTERN);CHKERRQ(ierr);
1376             ierr = MatDestroy(&T);CHKERRQ(ierr);
1377             /* set diagonal entry to a very large value to pick the basis we are eliminating as the first eigenvectors with adaptive selection */
1378             ierr = MatZeroRowsColumnsIS(SEj,sub_schurs->change_primal_sub[i],1./PETSC_SMALL,NULL,NULL);CHKERRQ(ierr);
1379             ierr = MatDestroy(&SEj);CHKERRQ(ierr);
1380           }
1381           for (j=0;j<subset_size;j++) dummy_idx[j] = cum+j;
1382           ierr = MatSetValues(sub_schurs->sum_S_Ej_tilda_all,subset_size,dummy_idx,subset_size,dummy_idx,work,INSERT_VALUES);CHKERRQ(ierr);
1383           cum += subset_size;
1384           cum2 += subset_size*(size_schur + 1);
1385         }
1386         ierr = MatDenseRestoreArray(S_all_inv,&S_data);CHKERRQ(ierr);
1387         if (solver_S) {
1388           ierr = MatFactorRestoreSchurComplement(F,&S_all_inv);CHKERRQ(ierr);
1389         }
1390         ierr = MatDestroy(&S_all_inv);CHKERRQ(ierr);
1391       }
1392 
1393       /* move back factors to Schur data into F */
1394       if (factor_workaround) {
1395         Mat S_tmp;
1396         PetscInt nv,nd=0;
1397 
1398         if (!solver_S) {
1399           SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"This should not happen");
1400         }
1401         ierr = ISGetLocalSize(sub_schurs->is_vertices,&nv);CHKERRQ(ierr);
1402         ierr = MatFactorGetSchurComplement(F,&S_tmp);CHKERRQ(ierr);
1403         if (sub_schurs->is_posdef) {
1404           PetscScalar *data;
1405 
1406           ierr = MatZeroEntries(S_tmp);CHKERRQ(ierr);
1407           ierr = MatDenseGetArray(S_tmp,&data);CHKERRQ(ierr);
1408 
1409           if (S_lower_triangular) {
1410             cum = 0;
1411             for (i=0;i<size_active_schur;i++) {
1412               ierr = PetscMemcpy(data+i*(size_schur+1),schur_factor+cum,(size_active_schur-i)*sizeof(PetscScalar));CHKERRQ(ierr);
1413               cum += size_active_schur-i;
1414 	    }
1415           } else {
1416             ierr = PetscMemcpy(data,schur_factor,size_schur*size_schur*sizeof(PetscScalar));CHKERRQ(ierr);
1417           }
1418           if (sub_schurs->is_dir) {
1419             ierr = ISGetLocalSize(sub_schurs->is_dir,&nd);CHKERRQ(ierr);
1420 	    for (i=0;i<nd;i++) {
1421 	      data[(i+size_active_schur)*(size_schur+1)] = schur_factor[cum+i];
1422 	    }
1423           }
1424           /* workaround: since I cannot modify the matrices used inside the solvers for the forward and backward substitutions,
1425              set the diagonal entry of the Schur factor to a very large value */
1426           for (i=size_active_schur+nd;i<size_schur;i++) {
1427             data[i*(size_schur+1)] = infty;
1428           }
1429           ierr = MatDenseRestoreArray(S_tmp,&data);CHKERRQ(ierr);
1430         } else {
1431           SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"Factor update not yet implemented for non SPD matrices");
1432         }
1433         ierr = MatFactorRestoreSchurComplement(F,&S_tmp);CHKERRQ(ierr);
1434       }
1435     } else if (factor_workaround) { /* we need to eliminate any unneeded coupling */
1436       PetscScalar *data;
1437       PetscInt    nd = 0;
1438 
1439       if (sub_schurs->is_dir) { /* dirichlet dofs could have different scalings */
1440         ierr = ISGetLocalSize(sub_schurs->is_dir,&nd);CHKERRQ(ierr);
1441       }
1442       ierr = MatFactorGetSchurComplement(F,&S_all);CHKERRQ(ierr);
1443       ierr = MatDenseGetArray(S_all,&data);CHKERRQ(ierr);
1444       for (i=0;i<size_active_schur;i++) {
1445         ierr = PetscMemzero(data+i*size_schur+size_active_schur,(size_schur-size_active_schur)*sizeof(PetscScalar));CHKERRQ(ierr);
1446       }
1447       for (i=size_active_schur+nd;i<size_schur;i++) {
1448         ierr = PetscMemzero(data+i*size_schur+size_active_schur,(size_schur-size_active_schur)*sizeof(PetscScalar));CHKERRQ(ierr);
1449         data[i*(size_schur+1)] = infty;
1450       }
1451       ierr = MatDenseRestoreArray(S_all,&data);CHKERRQ(ierr);
1452       ierr = MatFactorRestoreSchurComplement(F,&S_all);CHKERRQ(ierr);
1453     }
1454     ierr = PetscFree2(dummy_idx,work);CHKERRQ(ierr);
1455     ierr = PetscFree(schur_factor);CHKERRQ(ierr);
1456     ierr = VecDestroy(&Dall);CHKERRQ(ierr);
1457   }
1458   ierr = PetscFree(nnz);CHKERRQ(ierr);
1459   ierr = MatDestroy(&F);CHKERRQ(ierr);
1460   ierr = ISDestroy(&is_I_layer);CHKERRQ(ierr);
1461   ierr = MatDestroy(&S_all);CHKERRQ(ierr);
1462   ierr = MatDestroy(&A_BB);CHKERRQ(ierr);
1463   ierr = MatDestroy(&A_IB);CHKERRQ(ierr);
1464   ierr = MatDestroy(&A_BI);CHKERRQ(ierr);
1465   ierr = MatAssemblyBegin(sub_schurs->S_Ej_all,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1466   ierr = MatAssemblyEnd(sub_schurs->S_Ej_all,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1467   if (compute_Stilda) {
1468     ierr = MatAssemblyBegin(sub_schurs->sum_S_Ej_tilda_all,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1469     ierr = MatAssemblyEnd(sub_schurs->sum_S_Ej_tilda_all,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1470     if (deluxe) {
1471       ierr = MatAssemblyBegin(sub_schurs->sum_S_Ej_inv_all,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1472       ierr = MatAssemblyEnd(sub_schurs->sum_S_Ej_inv_all,MAT_FINAL_ASSEMBLY);CHKERRQ(ierr);
1473     }
1474   }
1475 
1476   /* Global matrix of all assembled Schur on subsets */
1477   ierr = MatISSetLocalMat(work_mat,sub_schurs->S_Ej_all);CHKERRQ(ierr);
1478   ierr = MatISSetMPIXAIJPreallocation_Private(work_mat,global_schur_subsets,PETSC_TRUE);CHKERRQ(ierr);
1479   ierr = MatISGetMPIXAIJ(work_mat,MAT_REUSE_MATRIX,&global_schur_subsets);CHKERRQ(ierr);
1480 
1481   /* Get local part of (\sum_j S_Ej) */
1482   if (!sub_schurs->sum_S_Ej_all) {
1483     ierr = MatGetSubMatrices(global_schur_subsets,1,&all_subsets_n,&all_subsets_n,MAT_INITIAL_MATRIX,&submats);CHKERRQ(ierr);
1484     sub_schurs->sum_S_Ej_all = submats[0];
1485   } else {
1486     ierr = PetscMalloc1(1,&submats);CHKERRQ(ierr);
1487     submats[0] = sub_schurs->sum_S_Ej_all;
1488     ierr = MatGetSubMatrices(global_schur_subsets,1,&all_subsets_n,&all_subsets_n,MAT_REUSE_MATRIX,&submats);CHKERRQ(ierr);
1489   }
1490 
1491   /* Get local part of (\sum_j S^-1_Ej) (\sum_j St^-1_Ej) */
1492   if (compute_Stilda) {
1493     ierr = MatISSetLocalMat(work_mat,sub_schurs->sum_S_Ej_tilda_all);CHKERRQ(ierr);
1494     ierr = MatISGetMPIXAIJ(work_mat,MAT_REUSE_MATRIX,&global_schur_subsets);CHKERRQ(ierr);
1495     submats[0] = sub_schurs->sum_S_Ej_tilda_all;
1496     ierr = MatGetSubMatrices(global_schur_subsets,1,&all_subsets_n,&all_subsets_n,MAT_REUSE_MATRIX,&submats);CHKERRQ(ierr);
1497     if (deluxe) {
1498       ierr = MatISSetLocalMat(work_mat,sub_schurs->sum_S_Ej_inv_all);CHKERRQ(ierr);
1499       ierr = MatISGetMPIXAIJ(work_mat,MAT_REUSE_MATRIX,&global_schur_subsets);CHKERRQ(ierr);
1500       submats[0] = sub_schurs->sum_S_Ej_inv_all;
1501       ierr = MatGetSubMatrices(global_schur_subsets,1,&all_subsets_n,&all_subsets_n,MAT_REUSE_MATRIX,&submats);CHKERRQ(ierr);
1502     } else {
1503       PetscScalar *array;
1504       PetscInt    cum;
1505 
1506       ierr = MatSeqAIJGetArray(sub_schurs->sum_S_Ej_tilda_all,&array);CHKERRQ(ierr);
1507       cum = 0;
1508       for (i=0;i<sub_schurs->n_subs;i++) {
1509         ierr = ISGetLocalSize(sub_schurs->is_subs[i],&subset_size);CHKERRQ(ierr);
1510         ierr = PetscBLASIntCast(subset_size,&B_N);CHKERRQ(ierr);
1511         ierr = PetscFPTrapPush(PETSC_FP_TRAP_OFF);CHKERRQ(ierr);
1512         PetscStackCallBLAS("LAPACKpotrf",LAPACKpotrf_("L",&B_N,array+cum,&B_N,&B_ierr));
1513         if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in POTRF Lapack routine %d",(int)B_ierr);
1514         PetscStackCallBLAS("LAPACKpotri",LAPACKpotri_("L",&B_N,array+cum,&B_N,&B_ierr));
1515         if (B_ierr) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in POTRI Lapack routine %d",(int)B_ierr);
1516         ierr = PetscFPTrapPop();CHKERRQ(ierr);
1517         cum += subset_size*subset_size;
1518       }
1519       ierr = MatSeqAIJRestoreArray(sub_schurs->sum_S_Ej_tilda_all,&array);CHKERRQ(ierr);
1520       ierr = PetscObjectReference((PetscObject)sub_schurs->sum_S_Ej_all);CHKERRQ(ierr);
1521       ierr = MatDestroy(&sub_schurs->sum_S_Ej_inv_all);CHKERRQ(ierr);
1522       sub_schurs->sum_S_Ej_inv_all = sub_schurs->sum_S_Ej_all;
1523     }
1524   }
1525 
1526   /* free workspace */
1527   ierr = PetscFree(submats);CHKERRQ(ierr);
1528   ierr = PetscFree2(Bwork,pivots);CHKERRQ(ierr);
1529   ierr = MatDestroy(&global_schur_subsets);CHKERRQ(ierr);
1530   ierr = MatDestroy(&work_mat);CHKERRQ(ierr);
1531   ierr = ISDestroy(&all_subsets_n);CHKERRQ(ierr);
1532   ierr = PetscCommDestroy(&comm_n);CHKERRQ(ierr);
1533   PetscFunctionReturn(0);
1534 }
1535 
1536 #undef __FUNCT__
1537 #define __FUNCT__ "PCBDDCSubSchursInit"
1538 PetscErrorCode PCBDDCSubSchursInit(PCBDDCSubSchurs sub_schurs, IS is_I, IS is_B, PCBDDCGraph graph, ISLocalToGlobalMapping BtoNmap, PetscBool copycc)
1539 {
1540   IS              *faces,*edges,*all_cc,vertices;
1541   PetscInt        i,n_faces,n_edges,n_all_cc;
1542   PetscBool       is_sorted;
1543   PetscErrorCode  ierr;
1544 
1545   PetscFunctionBegin;
1546   ierr = ISSorted(is_I,&is_sorted);CHKERRQ(ierr);
1547   if (!is_sorted) SETERRQ(PetscObjectComm((PetscObject)is_I),PETSC_ERR_PLIB,"IS for I dofs should be shorted");
1548   ierr = ISSorted(is_B,&is_sorted);CHKERRQ(ierr);
1549   if (!is_sorted) SETERRQ(PetscObjectComm((PetscObject)is_B),PETSC_ERR_PLIB,"IS for B dofs should be shorted");
1550 
1551   /* reset any previous data */
1552   ierr = PCBDDCSubSchursReset(sub_schurs);CHKERRQ(ierr);
1553 
1554   /* get index sets for faces and edges (already sorted by global ordering) */
1555   ierr = PCBDDCGraphGetCandidatesIS(graph,&n_faces,&faces,&n_edges,&edges,&vertices);CHKERRQ(ierr);
1556   n_all_cc = n_faces+n_edges;
1557   ierr = PetscBTCreate(n_all_cc,&sub_schurs->is_edge);CHKERRQ(ierr);
1558   ierr = PetscMalloc1(n_all_cc,&all_cc);CHKERRQ(ierr);
1559   for (i=0;i<n_faces;i++) {
1560     if (copycc) {
1561       ierr = ISDuplicate(faces[i],&all_cc[i]);CHKERRQ(ierr);
1562     } else {
1563       ierr = PetscObjectReference((PetscObject)faces[i]);CHKERRQ(ierr);
1564       all_cc[i] = faces[i];
1565     }
1566   }
1567   for (i=0;i<n_edges;i++) {
1568     if (copycc) {
1569       ierr = ISDuplicate(edges[i],&all_cc[n_faces+i]);CHKERRQ(ierr);
1570     } else {
1571       ierr = PetscObjectReference((PetscObject)edges[i]);CHKERRQ(ierr);
1572       all_cc[n_faces+i] = edges[i];
1573     }
1574     ierr = PetscBTSet(sub_schurs->is_edge,n_faces+i);CHKERRQ(ierr);
1575   }
1576   ierr = PetscObjectReference((PetscObject)vertices);CHKERRQ(ierr);
1577   sub_schurs->is_vertices = vertices;
1578   ierr = PCBDDCGraphRestoreCandidatesIS(graph,&n_faces,&faces,&n_edges,&edges,&vertices);CHKERRQ(ierr);
1579   sub_schurs->is_dir = NULL;
1580   ierr = PCBDDCGraphGetDirichletDofsB(graph,&sub_schurs->is_dir);CHKERRQ(ierr);
1581 
1582   /* Determine if MatFactor can be used */
1583   sub_schurs->schur_explicit = PETSC_FALSE;
1584 #if defined(PETSC_HAVE_MUMPS)
1585   sub_schurs->schur_explicit = PETSC_TRUE;
1586 #endif
1587 #if defined(PETSC_HAVE_MKL_PARDISO)
1588   sub_schurs->schur_explicit = PETSC_TRUE;
1589 #endif
1590 
1591   ierr = PetscObjectReference((PetscObject)is_I);CHKERRQ(ierr);
1592   sub_schurs->is_I = is_I;
1593   ierr = PetscObjectReference((PetscObject)is_B);CHKERRQ(ierr);
1594   sub_schurs->is_B = is_B;
1595   ierr = PetscObjectReference((PetscObject)graph->l2gmap);CHKERRQ(ierr);
1596   sub_schurs->l2gmap = graph->l2gmap;
1597   ierr = PetscObjectReference((PetscObject)BtoNmap);CHKERRQ(ierr);
1598   sub_schurs->BtoNmap = BtoNmap;
1599   sub_schurs->n_subs = n_all_cc;
1600   sub_schurs->is_subs = all_cc;
1601   if (!sub_schurs->schur_explicit) { /* sort by local ordering if we are not using MatFactor */
1602     for (i=0;i<sub_schurs->n_subs;i++) {
1603       ierr = ISSort(sub_schurs->is_subs[i]);CHKERRQ(ierr);
1604     }
1605   }
1606   sub_schurs->S_Ej_all = NULL;
1607   sub_schurs->sum_S_Ej_all = NULL;
1608   sub_schurs->sum_S_Ej_inv_all = NULL;
1609   sub_schurs->sum_S_Ej_tilda_all = NULL;
1610   sub_schurs->is_Ej_all = NULL;
1611   PetscFunctionReturn(0);
1612 }
1613 
1614 #undef __FUNCT__
1615 #define __FUNCT__ "PCBDDCSubSchursCreate"
1616 PetscErrorCode PCBDDCSubSchursCreate(PCBDDCSubSchurs *sub_schurs)
1617 {
1618   PCBDDCSubSchurs schurs_ctx;
1619   PetscErrorCode  ierr;
1620 
1621   PetscFunctionBegin;
1622   ierr = PetscNew(&schurs_ctx);CHKERRQ(ierr);
1623   schurs_ctx->n_subs = 0;
1624   *sub_schurs = schurs_ctx;
1625   PetscFunctionReturn(0);
1626 }
1627 
1628 #undef __FUNCT__
1629 #define __FUNCT__ "PCBDDCSubSchursReset"
1630 PetscErrorCode PCBDDCSubSchursReset(PCBDDCSubSchurs sub_schurs)
1631 {
1632   PetscInt       i;
1633   PetscErrorCode ierr;
1634 
1635   PetscFunctionBegin;
1636   if (!sub_schurs) PetscFunctionReturn(0);
1637   ierr = MatDestroy(&sub_schurs->A);CHKERRQ(ierr);
1638   ierr = MatDestroy(&sub_schurs->S);CHKERRQ(ierr);
1639   ierr = ISDestroy(&sub_schurs->is_I);CHKERRQ(ierr);
1640   ierr = ISDestroy(&sub_schurs->is_B);CHKERRQ(ierr);
1641   ierr = ISLocalToGlobalMappingDestroy(&sub_schurs->l2gmap);CHKERRQ(ierr);
1642   ierr = ISLocalToGlobalMappingDestroy(&sub_schurs->BtoNmap);CHKERRQ(ierr);
1643   ierr = MatDestroy(&sub_schurs->S_Ej_all);CHKERRQ(ierr);
1644   ierr = MatDestroy(&sub_schurs->sum_S_Ej_all);CHKERRQ(ierr);
1645   ierr = MatDestroy(&sub_schurs->sum_S_Ej_inv_all);CHKERRQ(ierr);
1646   ierr = MatDestroy(&sub_schurs->sum_S_Ej_tilda_all);CHKERRQ(ierr);
1647   ierr = ISDestroy(&sub_schurs->is_Ej_all);CHKERRQ(ierr);
1648   ierr = ISDestroy(&sub_schurs->is_vertices);CHKERRQ(ierr);
1649   ierr = ISDestroy(&sub_schurs->is_dir);CHKERRQ(ierr);
1650   ierr = PetscBTDestroy(&sub_schurs->is_edge);CHKERRQ(ierr);
1651   for (i=0;i<sub_schurs->n_subs;i++) {
1652     ierr = ISDestroy(&sub_schurs->is_subs[i]);CHKERRQ(ierr);
1653   }
1654   if (sub_schurs->n_subs) {
1655     ierr = PetscFree(sub_schurs->is_subs);CHKERRQ(ierr);
1656   }
1657   if (sub_schurs->reuse_solver) {
1658     ierr = PCBDDCReuseSolversReset(sub_schurs->reuse_solver);CHKERRQ(ierr);
1659   }
1660   ierr = PetscFree(sub_schurs->reuse_solver);CHKERRQ(ierr);
1661   if (sub_schurs->change) {
1662     for (i=0;i<sub_schurs->n_subs;i++) {
1663       ierr = KSPDestroy(&sub_schurs->change[i]);CHKERRQ(ierr);
1664       ierr = ISDestroy(&sub_schurs->change_primal_sub[i]);CHKERRQ(ierr);
1665     }
1666   }
1667   ierr = PetscFree(sub_schurs->change);CHKERRQ(ierr);
1668   ierr = PetscFree(sub_schurs->change_primal_sub);CHKERRQ(ierr);
1669   sub_schurs->n_subs = 0;
1670   PetscFunctionReturn(0);
1671 }
1672 
1673 #undef __FUNCT__
1674 #define __FUNCT__ "PCBDDCSubSchursDestroy"
1675 PetscErrorCode PCBDDCSubSchursDestroy(PCBDDCSubSchurs* sub_schurs)
1676 {
1677   PetscErrorCode ierr;
1678 
1679   PetscFunctionBegin;
1680   ierr = PCBDDCSubSchursReset(*sub_schurs);CHKERRQ(ierr);
1681   ierr = PetscFree(*sub_schurs);CHKERRQ(ierr);
1682   PetscFunctionReturn(0);
1683 }
1684 
1685 #undef __FUNCT__
1686 #define __FUNCT__ "PCBDDCAdjGetNextLayer_Private"
1687 PETSC_STATIC_INLINE PetscErrorCode PCBDDCAdjGetNextLayer_Private(PetscInt* queue_tip,PetscInt n_prev,PetscBT touched,PetscInt* xadj,PetscInt* adjncy,PetscInt* n_added)
1688 {
1689   PetscInt       i,j,n;
1690   PetscErrorCode ierr;
1691 
1692   PetscFunctionBegin;
1693   n = 0;
1694   for (i=-n_prev;i<0;i++) {
1695     PetscInt start_dof = queue_tip[i];
1696     for (j=xadj[start_dof];j<xadj[start_dof+1];j++) {
1697       PetscInt dof = adjncy[j];
1698       if (!PetscBTLookup(touched,dof)) {
1699         ierr = PetscBTSet(touched,dof);CHKERRQ(ierr);
1700         queue_tip[n] = dof;
1701         n++;
1702       }
1703     }
1704   }
1705   *n_added = n;
1706   PetscFunctionReturn(0);
1707 }
1708