xref: /petsc/src/ksp/pc/impls/bddc/bddcnullspace.c (revision 4fc747eaadbeca11629f314a99edccbc2ed7b3d3)
1 #include <../src/ksp/pc/impls/bddc/bddc.h>
2 #include <../src/ksp/pc/impls/bddc/bddcprivate.h>
3 
4 #undef __FUNCT__
5 #define __FUNCT__ "PCBDDCApplyNullSpaceCorrectionPC"
6 static PetscErrorCode PCBDDCApplyNullSpaceCorrectionPC(PC pc,Vec x,Vec y)
7 {
8   NullSpaceCorrection_ctx pc_ctx;
9   PetscErrorCode          ierr;
10 
11   PetscFunctionBegin;
12   ierr = PCShellGetContext(pc,(void**)&pc_ctx);CHKERRQ(ierr);
13   /* E */
14   ierr = MatMultTranspose(pc_ctx->Lbasis_mat,x,pc_ctx->work_small_2);CHKERRQ(ierr);
15   ierr = MatMultAdd(pc_ctx->Kbasis_mat,pc_ctx->work_small_2,x,pc_ctx->work_full_1);CHKERRQ(ierr);
16   /* P^-1 */
17   ierr = PCApply(pc_ctx->local_pc,pc_ctx->work_full_1,pc_ctx->work_full_2);CHKERRQ(ierr);
18   /* E^T */
19   ierr = MatMultTranspose(pc_ctx->Kbasis_mat,pc_ctx->work_full_2,pc_ctx->work_small_1);CHKERRQ(ierr);
20   ierr = VecScale(pc_ctx->work_small_1,-1.0);CHKERRQ(ierr);
21   ierr = MatMultAdd(pc_ctx->Lbasis_mat,pc_ctx->work_small_1,pc_ctx->work_full_2,pc_ctx->work_full_1);CHKERRQ(ierr);
22   /* Sum contributions */
23   ierr = MatMultAdd(pc_ctx->basis_mat,pc_ctx->work_small_2,pc_ctx->work_full_1,y);CHKERRQ(ierr);
24   if (pc_ctx->apply_scaling) {
25     ierr = VecScale(y,pc_ctx->scale);CHKERRQ(ierr);
26   }
27   PetscFunctionReturn(0);
28 }
29 
30 #undef __FUNCT__
31 #define __FUNCT__ "PCBDDCDestroyNullSpaceCorrectionPC"
32 static PetscErrorCode PCBDDCDestroyNullSpaceCorrectionPC(PC pc)
33 {
34   NullSpaceCorrection_ctx pc_ctx;
35   PetscErrorCode          ierr;
36 
37   PetscFunctionBegin;
38   ierr = PCShellGetContext(pc,(void**)&pc_ctx);CHKERRQ(ierr);
39   ierr = VecDestroy(&pc_ctx->work_small_1);CHKERRQ(ierr);
40   ierr = VecDestroy(&pc_ctx->work_small_2);CHKERRQ(ierr);
41   ierr = VecDestroy(&pc_ctx->work_full_1);CHKERRQ(ierr);
42   ierr = VecDestroy(&pc_ctx->work_full_2);CHKERRQ(ierr);
43   ierr = MatDestroy(&pc_ctx->basis_mat);CHKERRQ(ierr);
44   ierr = MatDestroy(&pc_ctx->Lbasis_mat);CHKERRQ(ierr);
45   ierr = MatDestroy(&pc_ctx->Kbasis_mat);CHKERRQ(ierr);
46   ierr = PCDestroy(&pc_ctx->local_pc);CHKERRQ(ierr);
47   ierr = PetscFree(pc_ctx);CHKERRQ(ierr);
48   PetscFunctionReturn(0);
49 }
50 
51 #undef __FUNCT__
52 #define __FUNCT__ "PCBDDCNullSpaceAssembleCorrection"
53 PetscErrorCode PCBDDCNullSpaceAssembleCorrection(PC pc, PetscBool isdir, PetscBool needscaling)
54 {
55   PC_BDDC                  *pcbddc = (PC_BDDC*)pc->data;
56   PC_IS                    *pcis = (PC_IS*)pc->data;
57   Mat_IS                   *matis = (Mat_IS*)pc->pmat->data;
58   MatNullSpace             NullSpace = NULL;
59   KSP                      local_ksp;
60   PC                       newpc;
61   NullSpaceCorrection_ctx  shell_ctx;
62   Mat                      local_mat,local_pmat,small_mat,inv_small_mat;
63   const Vec                *nullvecs;
64   VecScatter               scatter_ctx;
65   IS                       is_aux,local_dofs;
66   MatFactorInfo            matinfo;
67   PetscScalar              *basis_mat,*Kbasis_mat,*array,*array_mat;
68   PetscScalar              one = 1.0,zero = 0.0, m_one = -1.0;
69   PetscInt                 basis_dofs,basis_size,nnsp_size,i,k;
70   PetscBool                nnsp_has_cnst;
71   PetscReal                test_err,lambda_min,lambda_max;
72   PetscBool                setsym,issym=PETSC_FALSE;
73   PetscErrorCode           ierr;
74 
75   PetscFunctionBegin;
76   ierr = MatGetNullSpace(matis->A,&NullSpace);CHKERRQ(ierr);
77   if (!NullSpace) PetscFunctionReturn(0);
78   /* Infer the local solver */
79   if (isdir) {
80     /* Dirichlet solver */
81     local_ksp = pcbddc->ksp_D;
82     local_dofs = pcis->is_I_local;
83   } else {
84     /* Neumann solver */
85     local_ksp = pcbddc->ksp_R;
86     local_dofs = pcbddc->is_R_local;
87   }
88   ierr = ISGetSize(local_dofs,&basis_dofs);CHKERRQ(ierr);
89   ierr = KSPGetOperators(local_ksp,&local_mat,&local_pmat);CHKERRQ(ierr);
90 
91   /* Get null space vecs */
92   ierr = MatNullSpaceGetVecs(NullSpace,&nnsp_has_cnst,&nnsp_size,&nullvecs);CHKERRQ(ierr);
93   basis_size = nnsp_size;
94   if (nnsp_has_cnst) basis_size++;
95 
96    /* Create shell ctx */
97   ierr = PetscNew(&shell_ctx);CHKERRQ(ierr);
98   shell_ctx->apply_scaling = needscaling;
99 
100   /* Create work vectors in shell context */
101   ierr = VecCreate(PETSC_COMM_SELF,&shell_ctx->work_small_1);CHKERRQ(ierr);
102   ierr = VecSetSizes(shell_ctx->work_small_1,basis_size,basis_size);CHKERRQ(ierr);
103   ierr = VecSetType(shell_ctx->work_small_1,VECSEQ);CHKERRQ(ierr);
104   ierr = VecDuplicate(shell_ctx->work_small_1,&shell_ctx->work_small_2);CHKERRQ(ierr);
105   ierr = VecCreate(PETSC_COMM_SELF,&shell_ctx->work_full_1);CHKERRQ(ierr);
106   ierr = VecSetSizes(shell_ctx->work_full_1,basis_dofs,basis_dofs);CHKERRQ(ierr);
107   ierr = VecSetType(shell_ctx->work_full_1,VECSEQ);CHKERRQ(ierr);
108   ierr = VecDuplicate(shell_ctx->work_full_1,&shell_ctx->work_full_2);CHKERRQ(ierr);
109 
110   /* Allocate workspace */
111   ierr = MatCreateSeqDense(PETSC_COMM_SELF,basis_dofs,basis_size,NULL,&shell_ctx->basis_mat);CHKERRQ(ierr);
112   ierr = MatCreateSeqDense(PETSC_COMM_SELF,basis_dofs,basis_size,NULL,&shell_ctx->Kbasis_mat);CHKERRQ(ierr);
113   ierr = MatDenseGetArray(shell_ctx->basis_mat,&basis_mat);CHKERRQ(ierr);
114   ierr = MatDenseGetArray(shell_ctx->Kbasis_mat,&Kbasis_mat);CHKERRQ(ierr);
115 
116   /* Restrict local null space on selected dofs
117      and compute matrices N and K*N */
118   ierr = VecScatterCreate(pcis->vec1_N,local_dofs,shell_ctx->work_full_1,(IS)0,&scatter_ctx);CHKERRQ(ierr);
119   for (k=0;k<nnsp_size;k++) {
120     ierr = VecPlaceArray(shell_ctx->work_full_1,(const PetscScalar*)&basis_mat[k*basis_dofs]);CHKERRQ(ierr);
121     ierr = VecScatterBegin(scatter_ctx,nullvecs[k],shell_ctx->work_full_1,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
122     ierr = VecScatterEnd(scatter_ctx,nullvecs[k],shell_ctx->work_full_1,INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr);
123     ierr = VecPlaceArray(shell_ctx->work_full_2,(const PetscScalar*)&Kbasis_mat[k*basis_dofs]);CHKERRQ(ierr);
124     ierr = MatMult(local_mat,shell_ctx->work_full_1,shell_ctx->work_full_2);CHKERRQ(ierr);
125     ierr = VecResetArray(shell_ctx->work_full_1);CHKERRQ(ierr);
126     ierr = VecResetArray(shell_ctx->work_full_2);CHKERRQ(ierr);
127   }
128   if (nnsp_has_cnst) {
129     ierr = VecPlaceArray(shell_ctx->work_full_1,(const PetscScalar*)&basis_mat[k*basis_dofs]);CHKERRQ(ierr);
130     ierr = VecSet(shell_ctx->work_full_1,one);CHKERRQ(ierr);
131     ierr = VecPlaceArray(shell_ctx->work_full_2,(const PetscScalar*)&Kbasis_mat[k*basis_dofs]);CHKERRQ(ierr);
132     ierr = MatMult(local_mat,shell_ctx->work_full_1,shell_ctx->work_full_2);CHKERRQ(ierr);
133     ierr = VecResetArray(shell_ctx->work_full_1);CHKERRQ(ierr);
134     ierr = VecResetArray(shell_ctx->work_full_2);CHKERRQ(ierr);
135   }
136   ierr = VecScatterDestroy(&scatter_ctx);CHKERRQ(ierr);
137   ierr = MatDenseRestoreArray(shell_ctx->basis_mat,&basis_mat);CHKERRQ(ierr);
138   ierr = MatDenseRestoreArray(shell_ctx->Kbasis_mat,&Kbasis_mat);CHKERRQ(ierr);
139 
140   /* Assemble another Mat object in shell context */
141   ierr = MatTransposeMatMult(shell_ctx->basis_mat,shell_ctx->Kbasis_mat,MAT_INITIAL_MATRIX,PETSC_DEFAULT,&small_mat);CHKERRQ(ierr);
142   ierr = MatFactorInfoInitialize(&matinfo);CHKERRQ(ierr);
143   ierr = ISCreateStride(PETSC_COMM_SELF,basis_size,0,1,&is_aux);CHKERRQ(ierr);
144   ierr = MatLUFactor(small_mat,is_aux,is_aux,&matinfo);CHKERRQ(ierr);
145   ierr = ISDestroy(&is_aux);CHKERRQ(ierr);
146   ierr = PetscMalloc1(basis_size*basis_size,&array_mat);CHKERRQ(ierr);
147   for (k=0;k<basis_size;k++) {
148     ierr = VecSet(shell_ctx->work_small_1,zero);CHKERRQ(ierr);
149     ierr = VecSetValue(shell_ctx->work_small_1,k,one,INSERT_VALUES);CHKERRQ(ierr);
150     ierr = VecAssemblyBegin(shell_ctx->work_small_1);CHKERRQ(ierr);
151     ierr = VecAssemblyEnd(shell_ctx->work_small_1);CHKERRQ(ierr);
152     ierr = MatSolve(small_mat,shell_ctx->work_small_1,shell_ctx->work_small_2);CHKERRQ(ierr);
153     ierr = VecGetArrayRead(shell_ctx->work_small_2,(const PetscScalar**)&array);CHKERRQ(ierr);
154     for (i=0;i<basis_size;i++) {
155       array_mat[i*basis_size+k]=array[i];
156     }
157     ierr = VecRestoreArrayRead(shell_ctx->work_small_2,(const PetscScalar**)&array);CHKERRQ(ierr);
158   }
159   ierr = MatCreateSeqDense(PETSC_COMM_SELF,basis_size,basis_size,array_mat,&inv_small_mat);CHKERRQ(ierr);
160   ierr = MatMatMult(shell_ctx->basis_mat,inv_small_mat,MAT_INITIAL_MATRIX,PETSC_DEFAULT,&shell_ctx->Lbasis_mat);CHKERRQ(ierr);
161   ierr = PetscFree(array_mat);CHKERRQ(ierr);
162   ierr = MatDestroy(&inv_small_mat);CHKERRQ(ierr);
163   ierr = MatDestroy(&small_mat);CHKERRQ(ierr);
164   ierr = MatScale(shell_ctx->Kbasis_mat,m_one);CHKERRQ(ierr);
165 
166   /* Rebuild local PC */
167   ierr = KSPGetPC(local_ksp,&shell_ctx->local_pc);CHKERRQ(ierr);
168   ierr = PetscObjectReference((PetscObject)shell_ctx->local_pc);CHKERRQ(ierr);
169   ierr = PCCreate(PETSC_COMM_SELF,&newpc);CHKERRQ(ierr);
170   ierr = PCSetOperators(newpc,local_mat,local_mat);CHKERRQ(ierr);
171   ierr = PCSetType(newpc,PCSHELL);CHKERRQ(ierr);
172   ierr = PCShellSetContext(newpc,shell_ctx);CHKERRQ(ierr);
173   ierr = PCShellSetApply(newpc,PCBDDCApplyNullSpaceCorrectionPC);CHKERRQ(ierr);
174   ierr = PCShellSetDestroy(newpc,PCBDDCDestroyNullSpaceCorrectionPC);CHKERRQ(ierr);
175   ierr = PCSetUp(newpc);CHKERRQ(ierr);
176   ierr = KSPSetPC(local_ksp,newpc);CHKERRQ(ierr);
177   ierr = KSPSetUp(local_ksp);CHKERRQ(ierr);
178 
179   /* Create ksp object suitable for extreme eigenvalues' estimation */
180   if (needscaling) {
181     KSP check_ksp;
182     Vec *workv;
183 
184     ierr = KSPCreate(PETSC_COMM_SELF,&check_ksp);CHKERRQ(ierr);
185     ierr = KSPSetErrorIfNotConverged(check_ksp,pc->erroriffailure);CHKERRQ(ierr);
186     ierr = KSPSetOperators(check_ksp,local_mat,local_mat);CHKERRQ(ierr);
187     ierr = KSPSetTolerances(check_ksp,1.e-4,1.e-12,PETSC_DEFAULT,basis_dofs);CHKERRQ(ierr);
188     ierr = KSPSetComputeSingularValues(check_ksp,PETSC_TRUE);CHKERRQ(ierr);
189     ierr = MatIsSymmetricKnown(pc->pmat,&setsym,&issym);CHKERRQ(ierr);
190     if (issym) {
191       ierr = KSPSetType(check_ksp,KSPCG);CHKERRQ(ierr);
192     }
193     ierr = VecDuplicateVecs(shell_ctx->work_full_1,2,&workv);CHKERRQ(ierr);
194     ierr = KSPSetPC(check_ksp,newpc);CHKERRQ(ierr);
195     ierr = KSPSetUp(check_ksp);CHKERRQ(ierr);
196     ierr = VecSetRandom(workv[1],NULL);CHKERRQ(ierr);
197     ierr = MatMult(local_mat,workv[1],workv[0]);CHKERRQ(ierr);
198     ierr = KSPSolve(check_ksp,workv[0],workv[0]);CHKERRQ(ierr);
199     ierr = VecAXPY(workv[0],-1.,workv[1]);CHKERRQ(ierr);
200     ierr = VecNorm(workv[0],NORM_INFINITY,&test_err);CHKERRQ(ierr);
201     ierr = KSPComputeExtremeSingularValues(check_ksp,&lambda_max,&lambda_min);CHKERRQ(ierr);
202     ierr = KSPGetIterationNumber(check_ksp,&k);CHKERRQ(ierr);
203     if (pcbddc->dbg_flag) {
204       if (isdir) {
205         ierr = PetscViewerASCIISynchronizedPrintf(pcbddc->dbg_viewer,"Subdomain %04d infinity error for Dirichlet adapted solver (no scale) %1.14e (it %d, eigs %1.6e %1.6e)\n",PetscGlobalRank,test_err,k,lambda_min,lambda_max);CHKERRQ(ierr);
206       } else {
207         ierr = PetscViewerASCIISynchronizedPrintf(pcbddc->dbg_viewer,"Subdomain %04d infinity error for Neumann adapted solver (no scale) %1.14e (it %d, eigs %1.6e %1.6e)\n",PetscGlobalRank,test_err,k,lambda_min,lambda_max);CHKERRQ(ierr);
208       }
209     }
210     shell_ctx->scale = 1./lambda_max;
211     ierr = KSPDestroy(&check_ksp);CHKERRQ(ierr);
212     ierr = VecDestroyVecs(2,&workv);CHKERRQ(ierr);
213   }
214   ierr = PCDestroy(&newpc);CHKERRQ(ierr);
215   PetscFunctionReturn(0);
216 }
217 
218 #undef __FUNCT__
219 #define __FUNCT__ "PCBDDCNullSpaceCheckCorrection"
220 PetscErrorCode PCBDDCNullSpaceCheckCorrection(PC pc, PetscBool isdir)
221 {
222   PC_BDDC                  *pcbddc = (PC_BDDC*)pc->data;
223   Mat_IS                   *matis = (Mat_IS*)pc->pmat->data;
224   KSP                      check_ksp,local_ksp;
225   MatNullSpace             NullSpace = NULL;
226   NullSpaceCorrection_ctx  shell_ctx;
227   PC                       check_pc;
228   Mat                      test_mat,local_mat;
229   PetscReal                test_err,lambda_min,lambda_max;
230   PetscBool                setsym,issym=PETSC_FALSE;
231   Vec                      work1,work2,work3;
232   PetscInt                 k;
233   PetscErrorCode           ierr;
234 
235   PetscFunctionBegin;
236   ierr = MatGetNullSpace(matis->A,&NullSpace);CHKERRQ(ierr);
237   if (!NullSpace) PetscFunctionReturn(0);
238   if (!pcbddc->dbg_flag) PetscFunctionReturn(0);
239   if (isdir) local_ksp = pcbddc->ksp_D;
240   else local_ksp = pcbddc->ksp_R;
241   ierr = KSPGetOperators(local_ksp,&local_mat,NULL);CHKERRQ(ierr);
242   ierr = KSPGetPC(local_ksp,&check_pc);CHKERRQ(ierr);
243   ierr = PCShellGetContext(check_pc,(void**)&shell_ctx);CHKERRQ(ierr);
244   ierr = VecDuplicate(shell_ctx->work_full_1,&work1);CHKERRQ(ierr);
245   ierr = VecDuplicate(shell_ctx->work_full_1,&work2);CHKERRQ(ierr);
246   ierr = VecDuplicate(shell_ctx->work_full_1,&work3);CHKERRQ(ierr);
247 
248   ierr = VecSetRandom(shell_ctx->work_small_1,NULL);CHKERRQ(ierr);
249   ierr = MatMult(shell_ctx->basis_mat,shell_ctx->work_small_1,work1);CHKERRQ(ierr);
250   ierr = VecCopy(work1,work2);CHKERRQ(ierr);
251   ierr = MatMult(local_mat,work1,work3);CHKERRQ(ierr);
252   ierr = PCApply(check_pc,work3,work1);CHKERRQ(ierr);
253   ierr = VecAXPY(work1,-1.,work2);CHKERRQ(ierr);
254   ierr = VecNorm(work1,NORM_INFINITY,&test_err);CHKERRQ(ierr);
255   if (isdir) {
256     ierr = PetscViewerASCIISynchronizedPrintf(pcbddc->dbg_viewer,"Subdomain %04d infinity error for Dirichlet nullspace correction solver: %1.14e\n",PetscGlobalRank,test_err);CHKERRQ(ierr);
257   } else {
258     ierr = PetscViewerASCIISynchronizedPrintf(pcbddc->dbg_viewer,"Subdomain %04d infinity error for Neumann nullspace correction solver: %1.14e\n",PetscGlobalRank,test_err);CHKERRQ(ierr);
259   }
260 
261   ierr = MatTransposeMatMult(shell_ctx->Lbasis_mat,shell_ctx->Kbasis_mat,MAT_INITIAL_MATRIX,PETSC_DEFAULT,&test_mat);CHKERRQ(ierr);
262   ierr = MatShift(test_mat,1.);CHKERRQ(ierr);
263   ierr = MatNorm(test_mat,NORM_INFINITY,&test_err);CHKERRQ(ierr);
264   ierr = MatDestroy(&test_mat);CHKERRQ(ierr);
265   if (isdir) {
266     ierr = PetscViewerASCIISynchronizedPrintf(pcbddc->dbg_viewer,"Subdomain %04d infinity error for Dirichlet nullspace matrices: %1.14e\n",PetscGlobalRank,test_err);CHKERRQ(ierr);
267   } else {
268     ierr = PetscViewerASCIISynchronizedPrintf(pcbddc->dbg_viewer,"Subdomain %04d infinity error for Neumann nullspace matrices: %1.14e\n",PetscGlobalRank,test_err);CHKERRQ(ierr);
269   }
270 
271   /* Create ksp object suitable for extreme eigenvalues' estimation */
272   ierr = KSPCreate(PETSC_COMM_SELF,&check_ksp);CHKERRQ(ierr);
273   ierr = KSPSetErrorIfNotConverged(check_ksp,pc->erroriffailure);CHKERRQ(ierr);
274   ierr = KSPSetOperators(check_ksp,local_mat,local_mat);CHKERRQ(ierr);
275   ierr = KSPSetTolerances(check_ksp,1.e-10,1.e-8,PETSC_DEFAULT,PETSC_DEFAULT);CHKERRQ(ierr);
276   ierr = KSPSetComputeSingularValues(check_ksp,PETSC_TRUE);CHKERRQ(ierr);
277   ierr = MatIsSymmetricKnown(pc->pmat,&setsym,&issym);CHKERRQ(ierr);
278   if (issym) {
279     ierr = KSPSetType(check_ksp,KSPCG);CHKERRQ(ierr);
280   }
281   ierr = KSPSetPC(check_ksp,check_pc);CHKERRQ(ierr);
282   ierr = KSPSetUp(check_ksp);CHKERRQ(ierr);
283   ierr = VecSetRandom(work1,NULL);CHKERRQ(ierr);
284   ierr = MatMult(local_mat,work1,work2);CHKERRQ(ierr);
285   ierr = KSPSolve(check_ksp,work2,work2);CHKERRQ(ierr);
286   ierr = VecAXPY(work2,-1.,work1);CHKERRQ(ierr);
287   ierr = VecNorm(work2,NORM_INFINITY,&test_err);CHKERRQ(ierr);
288   ierr = KSPComputeExtremeSingularValues(check_ksp,&lambda_max,&lambda_min);CHKERRQ(ierr);
289   ierr = KSPGetIterationNumber(check_ksp,&k);CHKERRQ(ierr);
290   if (isdir) {
291     ierr = PetscViewerASCIISynchronizedPrintf(pcbddc->dbg_viewer,"Subdomain %04d infinity error for Dirichlet adapted KSP (scale %d) %1.14e (it %d, eigs %1.6e %1.6e)\n",PetscGlobalRank,shell_ctx->apply_scaling,test_err,k,lambda_min,lambda_max);CHKERRQ(ierr);
292   } else {
293     ierr = PetscViewerASCIISynchronizedPrintf(pcbddc->dbg_viewer,"Subdomain %04d infinity error for Neumann adapted KSP (scale %d) %1.14e (it %d, eigs %1.6e %1.6e)\n",PetscGlobalRank,shell_ctx->apply_scaling,test_err,k,lambda_min,lambda_max);CHKERRQ(ierr);
294   }
295   ierr = KSPDestroy(&check_ksp);CHKERRQ(ierr);
296   ierr = VecDestroy(&work1);CHKERRQ(ierr);
297   ierr = VecDestroy(&work2);CHKERRQ(ierr);
298   ierr = VecDestroy(&work3);CHKERRQ(ierr);
299   PetscFunctionReturn(0);
300 }
301