1 2 #include "src/ksp/pc/impls/is/pcis.h" 3 4 /* -------------------------------------------------------------------------- */ 5 /* 6 PCISSetUp - 7 */ 8 #undef __FUNCT__ 9 #define __FUNCT__ "PCISSetUp" 10 PetscErrorCode PCISSetUp(PC pc) 11 { 12 PC_IS *pcis = (PC_IS*)(pc->data); 13 Mat_IS *matis = (Mat_IS*)pc->mat->data; 14 PetscInt i; 15 PetscErrorCode ierr; 16 PetscTruth flg; 17 18 PetscFunctionBegin; 19 ierr = PetscTypeCompare((PetscObject)pc->mat,MATIS,&flg);CHKERRQ(ierr); 20 if (!flg){ 21 SETERRQ(PETSC_ERR_ARG_WRONG,"Preconditioner type of Neumann Neumman requires matrix of type MATIS"); 22 } 23 24 pcis->pure_neumann = matis->pure_neumann; 25 26 /* 27 Creating the local vector vec1_N, containing the inverse of the number 28 of subdomains to which each local node (either owned or ghost) 29 pertains. To accomplish that, we scatter local vectors of 1's to 30 a global vector (adding the values); scatter the result back to 31 local vectors and finally invert the result. 32 */ 33 { 34 Vec counter; 35 PetscScalar one=1.0, zero=0.0; 36 ierr = VecDuplicate(matis->x,&pcis->vec1_N);CHKERRQ(ierr); 37 ierr = MatGetVecs(pc->pmat,&counter,0);CHKERRQ(ierr); /* temporary auxiliar vector */ 38 ierr = VecSet(&zero,counter);CHKERRQ(ierr); 39 ierr = VecSet(&one,pcis->vec1_N);CHKERRQ(ierr); 40 ierr = VecScatterBegin(pcis->vec1_N,counter,ADD_VALUES,SCATTER_REVERSE,matis->ctx);CHKERRQ(ierr); 41 ierr = VecScatterEnd (pcis->vec1_N,counter,ADD_VALUES,SCATTER_REVERSE,matis->ctx);CHKERRQ(ierr); 42 ierr = VecScatterBegin(counter,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD,matis->ctx);CHKERRQ(ierr); 43 ierr = VecScatterEnd (counter,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD,matis->ctx);CHKERRQ(ierr); 44 ierr = VecDestroy(counter);CHKERRQ(ierr); 45 } 46 /* 47 Creating local and global index sets for interior and 48 inteface nodes. Notice that interior nodes have D[i]==1.0. 49 */ 50 { 51 PetscInt n_I; 52 PetscInt *idx_I_local,*idx_B_local,*idx_I_global,*idx_B_global; 53 PetscScalar *array; 54 /* Identifying interior and interface nodes, in local numbering */ 55 ierr = VecGetSize(pcis->vec1_N,&pcis->n);CHKERRQ(ierr); 56 ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr); 57 ierr = PetscMalloc(pcis->n*sizeof(PetscInt),&idx_I_local);CHKERRQ(ierr); 58 ierr = PetscMalloc(pcis->n*sizeof(PetscInt),&idx_B_local);CHKERRQ(ierr); 59 for (i=0, pcis->n_B=0, n_I=0; i<pcis->n; i++) { 60 if (array[i] == 1.0) { idx_I_local[n_I] = i; n_I++; } 61 else { idx_B_local[pcis->n_B] = i; pcis->n_B++; } 62 } 63 /* Getting the global numbering */ 64 idx_B_global = idx_I_local + n_I; /* Just avoiding allocating extra memory, since we have vacant space */ 65 idx_I_global = idx_B_local + pcis->n_B; 66 ierr = ISLocalToGlobalMappingApply(matis->mapping,pcis->n_B,idx_B_local,idx_B_global);CHKERRQ(ierr); 67 ierr = ISLocalToGlobalMappingApply(matis->mapping,n_I, idx_I_local,idx_I_global);CHKERRQ(ierr); 68 /* Creating the index sets. */ 69 ierr = ISCreateGeneral(MPI_COMM_SELF,pcis->n_B,idx_B_local, &pcis->is_B_local);CHKERRQ(ierr); 70 ierr = ISCreateGeneral(MPI_COMM_SELF,pcis->n_B,idx_B_global,&pcis->is_B_global);CHKERRQ(ierr); 71 ierr = ISCreateGeneral(MPI_COMM_SELF,n_I ,idx_I_local, &pcis->is_I_local);CHKERRQ(ierr); 72 ierr = ISCreateGeneral(MPI_COMM_SELF,n_I ,idx_I_global,&pcis->is_I_global);CHKERRQ(ierr); 73 /* Freeing memory and restoring arrays */ 74 ierr = PetscFree(idx_B_local);CHKERRQ(ierr); 75 ierr = PetscFree(idx_I_local);CHKERRQ(ierr); 76 ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr); 77 } 78 79 /* 80 Extracting the blocks A_II, A_BI, A_IB and A_BB from A. If the numbering 81 is such that interior nodes come first than the interface ones, we have 82 83 [ | ] 84 [ A_II | A_IB ] 85 A = [ | ] 86 [-----------+------] 87 [ A_BI | A_BB ] 88 */ 89 90 ierr = MatGetSubMatrix(matis->A,pcis->is_I_local,pcis->is_I_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_II);CHKERRQ(ierr); 91 ierr = MatGetSubMatrix(matis->A,pcis->is_I_local,pcis->is_B_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_IB);CHKERRQ(ierr); 92 ierr = MatGetSubMatrix(matis->A,pcis->is_B_local,pcis->is_I_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_BI);CHKERRQ(ierr); 93 ierr = MatGetSubMatrix(matis->A,pcis->is_B_local,pcis->is_B_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_BB);CHKERRQ(ierr); 94 95 /* 96 Creating work vectors and arrays 97 */ 98 /* pcis->vec1_N has already been created */ 99 ierr = VecDuplicate(pcis->vec1_N,&pcis->vec2_N);CHKERRQ(ierr); 100 ierr = VecCreateSeq(PETSC_COMM_SELF,pcis->n-pcis->n_B,&pcis->vec1_D);CHKERRQ(ierr); 101 ierr = VecDuplicate(pcis->vec1_D,&pcis->vec2_D);CHKERRQ(ierr); 102 ierr = VecDuplicate(pcis->vec1_D,&pcis->vec3_D);CHKERRQ(ierr); 103 ierr = VecCreateSeq(PETSC_COMM_SELF,pcis->n_B,&pcis->vec1_B);CHKERRQ(ierr); 104 ierr = VecDuplicate(pcis->vec1_B,&pcis->vec2_B);CHKERRQ(ierr); 105 ierr = VecDuplicate(pcis->vec1_B,&pcis->vec3_B);CHKERRQ(ierr); 106 ierr = MatGetVecs(pc->pmat,&pcis->vec1_global,0);CHKERRQ(ierr); 107 ierr = PetscMalloc((pcis->n)*sizeof(PetscScalar),&pcis->work_N);CHKERRQ(ierr); 108 109 /* Creating the scatter contexts */ 110 ierr = VecScatterCreate(pcis->vec1_global,pcis->is_I_global,pcis->vec1_D,(IS)0,&pcis->global_to_D);CHKERRQ(ierr); 111 ierr = VecScatterCreate(pcis->vec1_N,pcis->is_B_local,pcis->vec1_B,(IS)0,&pcis->N_to_B);CHKERRQ(ierr); 112 ierr = VecScatterCreate(pcis->vec1_global,pcis->is_B_global,pcis->vec1_B,(IS)0,&pcis->global_to_B);CHKERRQ(ierr); 113 114 /* Creating scaling "matrix" D, from information in vec1_N */ 115 ierr = VecDuplicate(pcis->vec1_B,&pcis->D);CHKERRQ(ierr); 116 ierr = VecScatterBegin(pcis->vec1_N,pcis->D,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 117 ierr = VecScatterEnd (pcis->vec1_N,pcis->D,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 118 ierr = VecReciprocal(pcis->D);CHKERRQ(ierr); 119 120 /* See historical note 01, at the bottom of this file. */ 121 122 /* 123 Creating the KSP contexts for the local Dirichlet and Neumann problems. 124 */ 125 { 126 PC pc_ctx; 127 /* Dirichlet */ 128 ierr = KSPCreate(PETSC_COMM_SELF,&pcis->ksp_D);CHKERRQ(ierr); 129 ierr = KSPSetOperators(pcis->ksp_D,pcis->A_II,pcis->A_II,SAME_PRECONDITIONER);CHKERRQ(ierr); 130 ierr = KSPSetOptionsPrefix(pcis->ksp_D,"is_localD_");CHKERRQ(ierr); 131 ierr = KSPGetPC(pcis->ksp_D,&pc_ctx);CHKERRQ(ierr); 132 ierr = PCSetType(pc_ctx,PCLU);CHKERRQ(ierr); 133 ierr = KSPSetType(pcis->ksp_D,KSPPREONLY);CHKERRQ(ierr); 134 ierr = KSPSetFromOptions(pcis->ksp_D);CHKERRQ(ierr); 135 /* the vectors in the following line are dummy arguments, just telling the KSP the vector size. Values are not used */ 136 ierr = KSPSetUp(pcis->ksp_D);CHKERRQ(ierr); 137 /* Neumann */ 138 ierr = KSPCreate(PETSC_COMM_SELF,&pcis->ksp_N);CHKERRQ(ierr); 139 ierr = KSPSetOperators(pcis->ksp_N,matis->A,matis->A,SAME_PRECONDITIONER);CHKERRQ(ierr); 140 ierr = KSPSetOptionsPrefix(pcis->ksp_N,"is_localN_");CHKERRQ(ierr); 141 ierr = KSPGetPC(pcis->ksp_N,&pc_ctx);CHKERRQ(ierr); 142 ierr = PCSetType(pc_ctx,PCLU);CHKERRQ(ierr); 143 ierr = KSPSetType(pcis->ksp_N,KSPPREONLY);CHKERRQ(ierr); 144 ierr = KSPSetFromOptions(pcis->ksp_N);CHKERRQ(ierr); 145 { 146 PetscTruth damp_fixed, 147 remove_nullspace_fixed, 148 set_damping_factor_floating, 149 not_damp_floating, 150 not_remove_nullspace_floating; 151 PetscReal fixed_factor, 152 floating_factor; 153 154 ierr = PetscOptionsGetReal(pc_ctx->prefix,"-pc_is_damp_fixed",&fixed_factor,&damp_fixed);CHKERRQ(ierr); 155 if (!damp_fixed) { fixed_factor = 0.0; } 156 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_damp_fixed",&damp_fixed);CHKERRQ(ierr); 157 158 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_remove_nullspace_fixed",&remove_nullspace_fixed);CHKERRQ(ierr); 159 160 ierr = PetscOptionsGetReal(pc_ctx->prefix,"-pc_is_set_damping_factor_floating", 161 &floating_factor,&set_damping_factor_floating);CHKERRQ(ierr); 162 if (!set_damping_factor_floating) { floating_factor = 0.0; } 163 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_set_damping_factor_floating",&set_damping_factor_floating);CHKERRQ(ierr); 164 if (!set_damping_factor_floating) { floating_factor = 1.e-12; } 165 166 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_not_damp_floating",¬_damp_floating);CHKERRQ(ierr); 167 168 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_not_remove_nullspace_floating",¬_remove_nullspace_floating);CHKERRQ(ierr); 169 170 if (pcis->pure_neumann) { /* floating subdomain */ 171 if (!(not_damp_floating)) { 172 ierr = PCFactorSetShiftNonzero(pc_ctx,floating_factor);CHKERRQ(ierr); 173 } 174 if (!(not_remove_nullspace_floating)){ 175 MatNullSpace nullsp; 176 ierr = MatNullSpaceCreate(PETSC_COMM_SELF,PETSC_TRUE,0,PETSC_NULL,&nullsp);CHKERRQ(ierr); 177 ierr = KSPSetNullSpace(pcis->ksp_N,nullsp);CHKERRQ(ierr); 178 ierr = MatNullSpaceDestroy(nullsp);CHKERRQ(ierr); 179 } 180 } else { /* fixed subdomain */ 181 if (damp_fixed) { 182 ierr = PCFactorSetShiftNonzero(pc_ctx,fixed_factor);CHKERRQ(ierr); 183 } 184 if (remove_nullspace_fixed) { 185 MatNullSpace nullsp; 186 ierr = MatNullSpaceCreate(PETSC_COMM_SELF,PETSC_TRUE,0,PETSC_NULL,&nullsp);CHKERRQ(ierr); 187 ierr = KSPSetNullSpace(pcis->ksp_N,nullsp);CHKERRQ(ierr); 188 ierr = MatNullSpaceDestroy(nullsp);CHKERRQ(ierr); 189 } 190 } 191 } 192 /* the vectors in the following line are dummy arguments, just telling the KSP the vector size. Values are not used */ 193 ierr = KSPSetUp(pcis->ksp_N);CHKERRQ(ierr); 194 } 195 196 ierr = ISLocalToGlobalMappingGetInfo(((Mat_IS*)(pc->mat->data))->mapping,&(pcis->n_neigh),&(pcis->neigh),&(pcis->n_shared),&(pcis->shared));CHKERRQ(ierr); 197 pcis->ISLocalToGlobalMappingGetInfoWasCalled = PETSC_TRUE; 198 PetscFunctionReturn(0); 199 } 200 201 /* -------------------------------------------------------------------------- */ 202 /* 203 PCISDestroy - 204 */ 205 #undef __FUNCT__ 206 #define __FUNCT__ "PCISDestroy" 207 PetscErrorCode PCISDestroy(PC pc) 208 { 209 PC_IS *pcis = (PC_IS*)(pc->data); 210 PetscErrorCode ierr; 211 212 PetscFunctionBegin; 213 if (pcis->is_B_local) {ierr = ISDestroy(pcis->is_B_local);CHKERRQ(ierr);} 214 if (pcis->is_I_local) {ierr = ISDestroy(pcis->is_I_local);CHKERRQ(ierr);} 215 if (pcis->is_B_global) {ierr = ISDestroy(pcis->is_B_global);CHKERRQ(ierr);} 216 if (pcis->is_I_global) {ierr = ISDestroy(pcis->is_I_global);CHKERRQ(ierr);} 217 if (pcis->A_II) {ierr = MatDestroy(pcis->A_II);CHKERRQ(ierr);} 218 if (pcis->A_IB) {ierr = MatDestroy(pcis->A_IB);CHKERRQ(ierr);} 219 if (pcis->A_BI) {ierr = MatDestroy(pcis->A_BI);CHKERRQ(ierr);} 220 if (pcis->A_BB) {ierr = MatDestroy(pcis->A_BB);CHKERRQ(ierr);} 221 if (pcis->D) {ierr = VecDestroy(pcis->D);CHKERRQ(ierr);} 222 if (pcis->ksp_N) {ierr = KSPDestroy(pcis->ksp_N);CHKERRQ(ierr);} 223 if (pcis->ksp_D) {ierr = KSPDestroy(pcis->ksp_D);CHKERRQ(ierr);} 224 if (pcis->vec1_N) {ierr = VecDestroy(pcis->vec1_N);CHKERRQ(ierr);} 225 if (pcis->vec2_N) {ierr = VecDestroy(pcis->vec2_N);CHKERRQ(ierr);} 226 if (pcis->vec1_D) {ierr = VecDestroy(pcis->vec1_D);CHKERRQ(ierr);} 227 if (pcis->vec2_D) {ierr = VecDestroy(pcis->vec2_D);CHKERRQ(ierr);} 228 if (pcis->vec3_D) {ierr = VecDestroy(pcis->vec3_D);CHKERRQ(ierr);} 229 if (pcis->vec1_B) {ierr = VecDestroy(pcis->vec1_B);CHKERRQ(ierr);} 230 if (pcis->vec2_B) {ierr = VecDestroy(pcis->vec2_B);CHKERRQ(ierr);} 231 if (pcis->vec3_B) {ierr = VecDestroy(pcis->vec3_B);CHKERRQ(ierr);} 232 if (pcis->vec1_global) {ierr = VecDestroy(pcis->vec1_global);CHKERRQ(ierr);} 233 if (pcis->work_N) {ierr = PetscFree(pcis->work_N);CHKERRQ(ierr);} 234 if (pcis->global_to_D) {ierr = VecScatterDestroy(pcis->global_to_D);CHKERRQ(ierr);} 235 if (pcis->N_to_B) {ierr = VecScatterDestroy(pcis->N_to_B);CHKERRQ(ierr);} 236 if (pcis->global_to_B) {ierr = VecScatterDestroy(pcis->global_to_B);CHKERRQ(ierr);} 237 if (pcis->ISLocalToGlobalMappingGetInfoWasCalled) { 238 ierr = ISLocalToGlobalMappingRestoreInfo((ISLocalToGlobalMapping)0,&(pcis->n_neigh),&(pcis->neigh),&(pcis->n_shared),&(pcis->shared));CHKERRQ(ierr); 239 } 240 PetscFunctionReturn(0); 241 } 242 243 /* -------------------------------------------------------------------------- */ 244 /* 245 PCISCreate - 246 */ 247 #undef __FUNCT__ 248 #define __FUNCT__ "PCISCreate" 249 PetscErrorCode PCISCreate(PC pc) 250 { 251 PC_IS *pcis = (PC_IS*)(pc->data); 252 253 PetscFunctionBegin; 254 pcis->is_B_local = 0; 255 pcis->is_I_local = 0; 256 pcis->is_B_global = 0; 257 pcis->is_I_global = 0; 258 pcis->A_II = 0; 259 pcis->A_IB = 0; 260 pcis->A_BI = 0; 261 pcis->A_BB = 0; 262 pcis->D = 0; 263 pcis->ksp_N = 0; 264 pcis->ksp_D = 0; 265 pcis->vec1_N = 0; 266 pcis->vec2_N = 0; 267 pcis->vec1_D = 0; 268 pcis->vec2_D = 0; 269 pcis->vec3_D = 0; 270 pcis->vec1_B = 0; 271 pcis->vec2_B = 0; 272 pcis->vec3_B = 0; 273 pcis->vec1_global = 0; 274 pcis->work_N = 0; 275 pcis->global_to_D = 0; 276 pcis->N_to_B = 0; 277 pcis->global_to_B = 0; 278 pcis->ISLocalToGlobalMappingGetInfoWasCalled = PETSC_FALSE; 279 PetscFunctionReturn(0); 280 } 281 282 /* -------------------------------------------------------------------------- */ 283 /* 284 PCISApplySchur - 285 286 Input parameters: 287 . pc - preconditioner context 288 . v - vector to which the Schur complement is to be applied (it is NOT modified inside this function, UNLESS vec2_B is null) 289 290 Output parameters: 291 . vec1_B - result of Schur complement applied to chunk 292 . vec2_B - garbage (used as work space), or null (and v is used as workspace) 293 . vec1_D - garbage (used as work space) 294 . vec2_D - garbage (used as work space) 295 296 */ 297 #undef __FUNCT__ 298 #define __FUNCT__ "PCIterSuApplySchur" 299 PetscErrorCode PCISApplySchur(PC pc, Vec v, Vec vec1_B, Vec vec2_B, Vec vec1_D, Vec vec2_D) 300 { 301 PetscErrorCode ierr; 302 PetscScalar m_one = -1.0; 303 PC_IS *pcis = (PC_IS*)(pc->data); 304 305 PetscFunctionBegin; 306 if (!vec2_B) { vec2_B = v; } 307 308 ierr = MatMult(pcis->A_BB,v,vec1_B);CHKERRQ(ierr); 309 ierr = MatMult(pcis->A_IB,v,vec1_D);CHKERRQ(ierr); 310 ierr = KSPSolve(pcis->ksp_D,vec1_D,vec2_D);CHKERRQ(ierr); 311 ierr = MatMult(pcis->A_BI,vec2_D,vec2_B);CHKERRQ(ierr); 312 ierr = VecAXPY(&m_one,vec2_B,vec1_B);CHKERRQ(ierr); 313 PetscFunctionReturn(0); 314 } 315 316 /* -------------------------------------------------------------------------- */ 317 /* 318 PCISScatterArrayNToVecB - Scatters interface node values from a big array (of all local nodes, interior or interface, 319 including ghosts) into an interface vector, when in SCATTER_FORWARD mode, or vice-versa, when in SCATTER_REVERSE 320 mode. 321 322 Input parameters: 323 . pc - preconditioner context 324 . array_N - [when in SCATTER_FORWARD mode] Array to be scattered into the vector 325 . v_B - [when in SCATTER_REVERSE mode] Vector to be scattered into the array 326 327 Output parameter: 328 . array_N - [when in SCATTER_REVERSE mode] Array to receive the scattered vector 329 . v_B - [when in SCATTER_FORWARD mode] Vector to receive the scattered array 330 331 Notes: 332 The entries in the array that do not correspond to interface nodes remain unaltered. 333 */ 334 #undef __FUNCT__ 335 #define __FUNCT__ "PCISScatterArrayNToVecB" 336 PetscErrorCode PCISScatterArrayNToVecB (PetscScalar *array_N, Vec v_B, InsertMode imode, ScatterMode smode, PC pc) 337 { 338 PetscInt i, *idex; 339 PetscErrorCode ierr; 340 PetscScalar *array_B; 341 PC_IS *pcis = (PC_IS*)(pc->data); 342 343 PetscFunctionBegin; 344 ierr = VecGetArray(v_B,&array_B);CHKERRQ(ierr); 345 ierr = ISGetIndices(pcis->is_B_local,&idex);CHKERRQ(ierr); 346 347 if (smode == SCATTER_FORWARD) { 348 if (imode == INSERT_VALUES) { 349 for (i=0; i<pcis->n_B; i++) { array_B[i] = array_N[idex[i]]; } 350 } else { /* ADD_VALUES */ 351 for (i=0; i<pcis->n_B; i++) { array_B[i] += array_N[idex[i]]; } 352 } 353 } else { /* SCATTER_REVERSE */ 354 if (imode == INSERT_VALUES) { 355 for (i=0; i<pcis->n_B; i++) { array_N[idex[i]] = array_B[i]; } 356 } else { /* ADD_VALUES */ 357 for (i=0; i<pcis->n_B; i++) { array_N[idex[i]] += array_B[i]; } 358 } 359 } 360 ierr = ISRestoreIndices(pcis->is_B_local,&idex);CHKERRQ(ierr); 361 ierr = VecRestoreArray(v_B,&array_B);CHKERRQ(ierr); 362 PetscFunctionReturn(0); 363 } 364 365 /* -------------------------------------------------------------------------- */ 366 /* 367 PCISApplyInvSchur - Solves the Neumann problem related to applying the inverse of the Schur complement. 368 More precisely, solves the problem: 369 [ A_II A_IB ] [ . ] [ 0 ] 370 [ ] [ ] = [ ] 371 [ A_BI A_BB ] [ x ] [ b ] 372 373 Input parameters: 374 . pc - preconditioner context 375 . b - vector of local interface nodes (including ghosts) 376 377 Output parameters: 378 . x - vector of local interface nodes (including ghosts); returns the application of the inverse of the Schur 379 complement to b 380 . vec1_N - vector of local nodes (interior and interface, including ghosts); returns garbage (used as work space) 381 . vec2_N - vector of local nodes (interior and interface, including ghosts); returns garbage (used as work space) 382 383 */ 384 #undef __FUNCT__ 385 #define __FUNCT__ "PCISApplyInvSchur" 386 PetscErrorCode PCISApplyInvSchur (PC pc, Vec b, Vec x, Vec vec1_N, Vec vec2_N) 387 { 388 PetscErrorCode ierr; 389 PC_IS *pcis = (PC_IS*)(pc->data); 390 PetscScalar zero = 0.0; 391 392 PetscFunctionBegin; 393 /* 394 Neumann solvers. 395 Applying the inverse of the local Schur complement, i.e, solving a Neumann 396 Problem with zero at the interior nodes of the RHS and extracting the interface 397 part of the solution. inverse Schur complement is applied to b and the result 398 is stored in x. 399 */ 400 /* Setting the RHS vec1_N */ 401 ierr = VecSet(&zero,vec1_N);CHKERRQ(ierr); 402 ierr = VecScatterBegin(b,vec1_N,INSERT_VALUES,SCATTER_REVERSE,pcis->N_to_B);CHKERRQ(ierr); 403 ierr = VecScatterEnd (b,vec1_N,INSERT_VALUES,SCATTER_REVERSE,pcis->N_to_B);CHKERRQ(ierr); 404 /* Checking for consistency of the RHS */ 405 { 406 PetscTruth flg; 407 ierr = PetscOptionsHasName(PETSC_NULL,"-pc_is_check_consistency",&flg);CHKERRQ(ierr); 408 if (flg) { 409 PetscScalar average; 410 ierr = VecSum(vec1_N,&average);CHKERRQ(ierr); 411 average = average / ((PetscReal)pcis->n); 412 if (pcis->pure_neumann) { 413 ierr = PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_(pc->comm),"Subdomain %04d is floating. Average = % 1.14e\n", 414 PetscGlobalRank,PetscAbsScalar(average));CHKERRQ(ierr); 415 } else { 416 ierr = PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_(pc->comm),"Subdomain %04d is fixed. Average = % 1.14e\n", 417 PetscGlobalRank,PetscAbsScalar(average));CHKERRQ(ierr); 418 } 419 PetscViewerFlush(PETSC_VIEWER_STDOUT_(pc->comm)); 420 } 421 } 422 /* Solving the system for vec2_N */ 423 ierr = KSPSolve(pcis->ksp_N,vec1_N,vec2_N);CHKERRQ(ierr); 424 /* Extracting the local interface vector out of the solution */ 425 ierr = VecScatterBegin(vec2_N,x,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 426 ierr = VecScatterEnd (vec2_N,x,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 427 PetscFunctionReturn(0); 428 } 429 430 431 432 433 434 435 436 437 438