1 2 #include "src/ksp/pc/impls/is/pcis.h" 3 #include "src/ksp/pc/impls/factor/lu/lu.h" 4 5 /* -------------------------------------------------------------------------- */ 6 /* 7 PCISSetUp - 8 */ 9 #undef __FUNCT__ 10 #define __FUNCT__ "PCISSetUp" 11 PetscErrorCode PCISSetUp(PC pc) 12 { 13 PC_IS *pcis = (PC_IS*)(pc->data); 14 Mat_IS *matis = (Mat_IS*)pc->mat->data; 15 PetscInt i; 16 PetscErrorCode ierr; 17 PetscTruth flg; 18 19 PetscFunctionBegin; 20 ierr = PetscTypeCompare((PetscObject)pc->mat,MATIS,&flg);CHKERRQ(ierr); 21 if (!flg){ 22 SETERRQ(PETSC_ERR_ARG_WRONG,"Preconditioner type of Neumann Neumman requires matrix of type MATIS"); 23 } 24 25 pcis->pure_neumann = matis->pure_neumann; 26 27 /* 28 Creating the local vector vec1_N, containing the inverse of the number 29 of subdomains to which each local node (either owned or ghost) 30 pertains. To accomplish that, we scatter local vectors of 1's to 31 a global vector (adding the values); scatter the result back to 32 local vectors and finally invert the result. 33 */ 34 { 35 Vec counter; 36 PetscScalar one=1.0, zero=0.0; 37 ierr = VecDuplicate(matis->x,&pcis->vec1_N);CHKERRQ(ierr); 38 ierr = MatGetVecs(pc->pmat,&counter,0);CHKERRQ(ierr); /* temporary auxiliar vector */ 39 ierr = VecSet(&zero,counter);CHKERRQ(ierr); 40 ierr = VecSet(&one,pcis->vec1_N);CHKERRQ(ierr); 41 ierr = VecScatterBegin(pcis->vec1_N,counter,ADD_VALUES,SCATTER_REVERSE,matis->ctx);CHKERRQ(ierr); 42 ierr = VecScatterEnd (pcis->vec1_N,counter,ADD_VALUES,SCATTER_REVERSE,matis->ctx);CHKERRQ(ierr); 43 ierr = VecScatterBegin(counter,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD,matis->ctx);CHKERRQ(ierr); 44 ierr = VecScatterEnd (counter,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD,matis->ctx);CHKERRQ(ierr); 45 ierr = VecDestroy(counter);CHKERRQ(ierr); 46 } 47 /* 48 Creating local and global index sets for interior and 49 inteface nodes. Notice that interior nodes have D[i]==1.0. 50 */ 51 { 52 PetscInt n_I; 53 PetscInt *idx_I_local,*idx_B_local,*idx_I_global,*idx_B_global; 54 PetscScalar *array; 55 /* Identifying interior and interface nodes, in local numbering */ 56 ierr = VecGetSize(pcis->vec1_N,&pcis->n);CHKERRQ(ierr); 57 ierr = VecGetArray(pcis->vec1_N,&array);CHKERRQ(ierr); 58 ierr = PetscMalloc(pcis->n*sizeof(PetscInt),&idx_I_local);CHKERRQ(ierr); 59 ierr = PetscMalloc(pcis->n*sizeof(PetscInt),&idx_B_local);CHKERRQ(ierr); 60 for (i=0, pcis->n_B=0, n_I=0; i<pcis->n; i++) { 61 if (array[i] == 1.0) { idx_I_local[n_I] = i; n_I++; } 62 else { idx_B_local[pcis->n_B] = i; pcis->n_B++; } 63 } 64 /* Getting the global numbering */ 65 idx_B_global = idx_I_local + n_I; /* Just avoiding allocating extra memory, since we have vacant space */ 66 idx_I_global = idx_B_local + pcis->n_B; 67 ierr = ISLocalToGlobalMappingApply(matis->mapping,pcis->n_B,idx_B_local,idx_B_global);CHKERRQ(ierr); 68 ierr = ISLocalToGlobalMappingApply(matis->mapping,n_I, idx_I_local,idx_I_global);CHKERRQ(ierr); 69 /* Creating the index sets. */ 70 ierr = ISCreateGeneral(MPI_COMM_SELF,pcis->n_B,idx_B_local, &pcis->is_B_local);CHKERRQ(ierr); 71 ierr = ISCreateGeneral(MPI_COMM_SELF,pcis->n_B,idx_B_global,&pcis->is_B_global);CHKERRQ(ierr); 72 ierr = ISCreateGeneral(MPI_COMM_SELF,n_I ,idx_I_local, &pcis->is_I_local);CHKERRQ(ierr); 73 ierr = ISCreateGeneral(MPI_COMM_SELF,n_I ,idx_I_global,&pcis->is_I_global);CHKERRQ(ierr); 74 /* Freeing memory and restoring arrays */ 75 ierr = PetscFree(idx_B_local);CHKERRQ(ierr); 76 ierr = PetscFree(idx_I_local);CHKERRQ(ierr); 77 ierr = VecRestoreArray(pcis->vec1_N,&array);CHKERRQ(ierr); 78 } 79 80 /* 81 Extracting the blocks A_II, A_BI, A_IB and A_BB from A. If the numbering 82 is such that interior nodes come first than the interface ones, we have 83 84 [ | ] 85 [ A_II | A_IB ] 86 A = [ | ] 87 [-----------+------] 88 [ A_BI | A_BB ] 89 */ 90 91 ierr = MatGetSubMatrix(matis->A,pcis->is_I_local,pcis->is_I_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_II);CHKERRQ(ierr); 92 ierr = MatGetSubMatrix(matis->A,pcis->is_I_local,pcis->is_B_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_IB);CHKERRQ(ierr); 93 ierr = MatGetSubMatrix(matis->A,pcis->is_B_local,pcis->is_I_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_BI);CHKERRQ(ierr); 94 ierr = MatGetSubMatrix(matis->A,pcis->is_B_local,pcis->is_B_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_BB);CHKERRQ(ierr); 95 96 /* 97 Creating work vectors and arrays 98 */ 99 /* pcis->vec1_N has already been created */ 100 ierr = VecDuplicate(pcis->vec1_N,&pcis->vec2_N);CHKERRQ(ierr); 101 ierr = VecCreateSeq(PETSC_COMM_SELF,pcis->n-pcis->n_B,&pcis->vec1_D);CHKERRQ(ierr); 102 ierr = VecDuplicate(pcis->vec1_D,&pcis->vec2_D);CHKERRQ(ierr); 103 ierr = VecDuplicate(pcis->vec1_D,&pcis->vec3_D);CHKERRQ(ierr); 104 ierr = VecCreateSeq(PETSC_COMM_SELF,pcis->n_B,&pcis->vec1_B);CHKERRQ(ierr); 105 ierr = VecDuplicate(pcis->vec1_B,&pcis->vec2_B);CHKERRQ(ierr); 106 ierr = VecDuplicate(pcis->vec1_B,&pcis->vec3_B);CHKERRQ(ierr); 107 ierr = MatGetVecs(pc->pmat,&pcis->vec1_global,0);CHKERRQ(ierr); 108 ierr = PetscMalloc((pcis->n)*sizeof(PetscScalar),&pcis->work_N);CHKERRQ(ierr); 109 110 /* Creating the scatter contexts */ 111 ierr = VecScatterCreate(pcis->vec1_global,pcis->is_I_global,pcis->vec1_D,(IS)0,&pcis->global_to_D);CHKERRQ(ierr); 112 ierr = VecScatterCreate(pcis->vec1_N,pcis->is_B_local,pcis->vec1_B,(IS)0,&pcis->N_to_B);CHKERRQ(ierr); 113 ierr = VecScatterCreate(pcis->vec1_global,pcis->is_B_global,pcis->vec1_B,(IS)0,&pcis->global_to_B);CHKERRQ(ierr); 114 115 /* Creating scaling "matrix" D, from information in vec1_N */ 116 ierr = VecDuplicate(pcis->vec1_B,&pcis->D);CHKERRQ(ierr); 117 ierr = VecScatterBegin(pcis->vec1_N,pcis->D,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 118 ierr = VecScatterEnd (pcis->vec1_N,pcis->D,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 119 ierr = VecReciprocal(pcis->D);CHKERRQ(ierr); 120 121 /* See historical note 01, at the bottom of this file. */ 122 123 /* 124 Creating the KSP contexts for the local Dirichlet and Neumann problems. 125 */ 126 { 127 PC pc_ctx; 128 /* Dirichlet */ 129 ierr = KSPCreate(PETSC_COMM_SELF,&pcis->ksp_D);CHKERRQ(ierr); 130 ierr = KSPSetOperators(pcis->ksp_D,pcis->A_II,pcis->A_II,SAME_PRECONDITIONER);CHKERRQ(ierr); 131 ierr = KSPSetOptionsPrefix(pcis->ksp_D,"is_localD_");CHKERRQ(ierr); 132 ierr = KSPGetPC(pcis->ksp_D,&pc_ctx);CHKERRQ(ierr); 133 ierr = PCSetType(pc_ctx,PCLU);CHKERRQ(ierr); 134 ierr = KSPSetType(pcis->ksp_D,KSPPREONLY);CHKERRQ(ierr); 135 ierr = KSPSetFromOptions(pcis->ksp_D);CHKERRQ(ierr); 136 /* the vectors in the following line are dummy arguments, just telling the KSP the vector size. Values are not used */ 137 ierr = KSPSetUp(pcis->ksp_D);CHKERRQ(ierr); 138 /* Neumann */ 139 ierr = KSPCreate(PETSC_COMM_SELF,&pcis->ksp_N);CHKERRQ(ierr); 140 ierr = KSPSetOperators(pcis->ksp_N,matis->A,matis->A,SAME_PRECONDITIONER);CHKERRQ(ierr); 141 ierr = KSPSetOptionsPrefix(pcis->ksp_N,"is_localN_");CHKERRQ(ierr); 142 ierr = KSPGetPC(pcis->ksp_N,&pc_ctx);CHKERRQ(ierr); 143 ierr = PCSetType(pc_ctx,PCLU);CHKERRQ(ierr); 144 ierr = KSPSetType(pcis->ksp_N,KSPPREONLY);CHKERRQ(ierr); 145 ierr = KSPSetFromOptions(pcis->ksp_N);CHKERRQ(ierr); 146 { 147 PetscTruth damp_fixed, 148 remove_nullspace_fixed, 149 set_damping_factor_floating, 150 not_damp_floating, 151 not_remove_nullspace_floating; 152 PetscReal fixed_factor, 153 floating_factor; 154 155 ierr = PetscOptionsGetReal(pc_ctx->prefix,"-pc_is_damp_fixed",&fixed_factor,&damp_fixed);CHKERRQ(ierr); 156 if (!damp_fixed) { fixed_factor = 0.0; } 157 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_damp_fixed",&damp_fixed);CHKERRQ(ierr); 158 159 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_remove_nullspace_fixed",&remove_nullspace_fixed);CHKERRQ(ierr); 160 161 ierr = PetscOptionsGetReal(pc_ctx->prefix,"-pc_is_set_damping_factor_floating", 162 &floating_factor,&set_damping_factor_floating);CHKERRQ(ierr); 163 if (!set_damping_factor_floating) { floating_factor = 0.0; } 164 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_set_damping_factor_floating",&set_damping_factor_floating);CHKERRQ(ierr); 165 if (!set_damping_factor_floating) { floating_factor = 1.e-12; } 166 167 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_not_damp_floating",¬_damp_floating);CHKERRQ(ierr); 168 169 ierr = PetscOptionsHasName(pc_ctx->prefix,"-pc_is_not_remove_nullspace_floating",¬_remove_nullspace_floating);CHKERRQ(ierr); 170 171 if (pcis->pure_neumann) { /* floating subdomain */ 172 if (!(not_damp_floating)) { 173 ierr = PCFactorSetShiftNonzero(floating_factor,&((PC_LU*)pc_ctx->data)->info);CHKERRQ(ierr); 174 } 175 if (!(not_remove_nullspace_floating)){ 176 MatNullSpace nullsp; 177 ierr = MatNullSpaceCreate(PETSC_COMM_SELF,PETSC_TRUE,0,PETSC_NULL,&nullsp);CHKERRQ(ierr); 178 ierr = KSPSetNullSpace(pcis->ksp_N,nullsp);CHKERRQ(ierr); 179 ierr = MatNullSpaceDestroy(nullsp);CHKERRQ(ierr); 180 } 181 } else { /* fixed subdomain */ 182 if (damp_fixed) { 183 ierr = PCFactorSetShiftNonzero(fixed_factor,&((PC_LU*)pc_ctx->data)->info);CHKERRQ(ierr); 184 } 185 if (remove_nullspace_fixed) { 186 MatNullSpace nullsp; 187 ierr = MatNullSpaceCreate(PETSC_COMM_SELF,PETSC_TRUE,0,PETSC_NULL,&nullsp);CHKERRQ(ierr); 188 ierr = KSPSetNullSpace(pcis->ksp_N,nullsp);CHKERRQ(ierr); 189 ierr = MatNullSpaceDestroy(nullsp);CHKERRQ(ierr); 190 } 191 } 192 } 193 /* the vectors in the following line are dummy arguments, just telling the KSP the vector size. Values are not used */ 194 ierr = KSPSetUp(pcis->ksp_N);CHKERRQ(ierr); 195 } 196 197 ierr = ISLocalToGlobalMappingGetInfo(((Mat_IS*)(pc->mat->data))->mapping,&(pcis->n_neigh),&(pcis->neigh),&(pcis->n_shared),&(pcis->shared));CHKERRQ(ierr); 198 pcis->ISLocalToGlobalMappingGetInfoWasCalled = PETSC_TRUE; 199 PetscFunctionReturn(0); 200 } 201 202 /* -------------------------------------------------------------------------- */ 203 /* 204 PCISDestroy - 205 */ 206 #undef __FUNCT__ 207 #define __FUNCT__ "PCISDestroy" 208 PetscErrorCode PCISDestroy(PC pc) 209 { 210 PC_IS *pcis = (PC_IS*)(pc->data); 211 PetscErrorCode ierr; 212 213 PetscFunctionBegin; 214 if (pcis->is_B_local) {ierr = ISDestroy(pcis->is_B_local);CHKERRQ(ierr);} 215 if (pcis->is_I_local) {ierr = ISDestroy(pcis->is_I_local);CHKERRQ(ierr);} 216 if (pcis->is_B_global) {ierr = ISDestroy(pcis->is_B_global);CHKERRQ(ierr);} 217 if (pcis->is_I_global) {ierr = ISDestroy(pcis->is_I_global);CHKERRQ(ierr);} 218 if (pcis->A_II) {ierr = MatDestroy(pcis->A_II);CHKERRQ(ierr);} 219 if (pcis->A_IB) {ierr = MatDestroy(pcis->A_IB);CHKERRQ(ierr);} 220 if (pcis->A_BI) {ierr = MatDestroy(pcis->A_BI);CHKERRQ(ierr);} 221 if (pcis->A_BB) {ierr = MatDestroy(pcis->A_BB);CHKERRQ(ierr);} 222 if (pcis->D) {ierr = VecDestroy(pcis->D);CHKERRQ(ierr);} 223 if (pcis->ksp_N) {ierr = KSPDestroy(pcis->ksp_N);CHKERRQ(ierr);} 224 if (pcis->ksp_D) {ierr = KSPDestroy(pcis->ksp_D);CHKERRQ(ierr);} 225 if (pcis->vec1_N) {ierr = VecDestroy(pcis->vec1_N);CHKERRQ(ierr);} 226 if (pcis->vec2_N) {ierr = VecDestroy(pcis->vec2_N);CHKERRQ(ierr);} 227 if (pcis->vec1_D) {ierr = VecDestroy(pcis->vec1_D);CHKERRQ(ierr);} 228 if (pcis->vec2_D) {ierr = VecDestroy(pcis->vec2_D);CHKERRQ(ierr);} 229 if (pcis->vec3_D) {ierr = VecDestroy(pcis->vec3_D);CHKERRQ(ierr);} 230 if (pcis->vec1_B) {ierr = VecDestroy(pcis->vec1_B);CHKERRQ(ierr);} 231 if (pcis->vec2_B) {ierr = VecDestroy(pcis->vec2_B);CHKERRQ(ierr);} 232 if (pcis->vec3_B) {ierr = VecDestroy(pcis->vec3_B);CHKERRQ(ierr);} 233 if (pcis->vec1_global) {ierr = VecDestroy(pcis->vec1_global);CHKERRQ(ierr);} 234 if (pcis->work_N) {ierr = PetscFree(pcis->work_N);CHKERRQ(ierr);} 235 if (pcis->global_to_D) {ierr = VecScatterDestroy(pcis->global_to_D);CHKERRQ(ierr);} 236 if (pcis->N_to_B) {ierr = VecScatterDestroy(pcis->N_to_B);CHKERRQ(ierr);} 237 if (pcis->global_to_B) {ierr = VecScatterDestroy(pcis->global_to_B);CHKERRQ(ierr);} 238 if (pcis->ISLocalToGlobalMappingGetInfoWasCalled) { 239 ierr = ISLocalToGlobalMappingRestoreInfo((ISLocalToGlobalMapping)0,&(pcis->n_neigh),&(pcis->neigh),&(pcis->n_shared),&(pcis->shared));CHKERRQ(ierr); 240 } 241 PetscFunctionReturn(0); 242 } 243 244 /* -------------------------------------------------------------------------- */ 245 /* 246 PCISCreate - 247 */ 248 #undef __FUNCT__ 249 #define __FUNCT__ "PCISCreate" 250 PetscErrorCode PCISCreate(PC pc) 251 { 252 PC_IS *pcis = (PC_IS*)(pc->data); 253 254 PetscFunctionBegin; 255 pcis->is_B_local = 0; 256 pcis->is_I_local = 0; 257 pcis->is_B_global = 0; 258 pcis->is_I_global = 0; 259 pcis->A_II = 0; 260 pcis->A_IB = 0; 261 pcis->A_BI = 0; 262 pcis->A_BB = 0; 263 pcis->D = 0; 264 pcis->ksp_N = 0; 265 pcis->ksp_D = 0; 266 pcis->vec1_N = 0; 267 pcis->vec2_N = 0; 268 pcis->vec1_D = 0; 269 pcis->vec2_D = 0; 270 pcis->vec3_D = 0; 271 pcis->vec1_B = 0; 272 pcis->vec2_B = 0; 273 pcis->vec3_B = 0; 274 pcis->vec1_global = 0; 275 pcis->work_N = 0; 276 pcis->global_to_D = 0; 277 pcis->N_to_B = 0; 278 pcis->global_to_B = 0; 279 pcis->ISLocalToGlobalMappingGetInfoWasCalled = PETSC_FALSE; 280 PetscFunctionReturn(0); 281 } 282 283 /* -------------------------------------------------------------------------- */ 284 /* 285 PCISApplySchur - 286 287 Input parameters: 288 . pc - preconditioner context 289 . v - vector to which the Schur complement is to be applied (it is NOT modified inside this function, UNLESS vec2_B is null) 290 291 Output parameters: 292 . vec1_B - result of Schur complement applied to chunk 293 . vec2_B - garbage (used as work space), or null (and v is used as workspace) 294 . vec1_D - garbage (used as work space) 295 . vec2_D - garbage (used as work space) 296 297 */ 298 #undef __FUNCT__ 299 #define __FUNCT__ "PCIterSuApplySchur" 300 PetscErrorCode PCISApplySchur(PC pc, Vec v, Vec vec1_B, Vec vec2_B, Vec vec1_D, Vec vec2_D) 301 { 302 PetscErrorCode ierr; 303 PetscScalar m_one = -1.0; 304 PC_IS *pcis = (PC_IS*)(pc->data); 305 306 PetscFunctionBegin; 307 if (!vec2_B) { vec2_B = v; } 308 309 ierr = MatMult(pcis->A_BB,v,vec1_B);CHKERRQ(ierr); 310 ierr = MatMult(pcis->A_IB,v,vec1_D);CHKERRQ(ierr); 311 ierr = KSPSolve(pcis->ksp_D,vec1_D,vec2_D);CHKERRQ(ierr); 312 ierr = MatMult(pcis->A_BI,vec2_D,vec2_B);CHKERRQ(ierr); 313 ierr = VecAXPY(&m_one,vec2_B,vec1_B);CHKERRQ(ierr); 314 PetscFunctionReturn(0); 315 } 316 317 /* -------------------------------------------------------------------------- */ 318 /* 319 PCISScatterArrayNToVecB - Scatters interface node values from a big array (of all local nodes, interior or interface, 320 including ghosts) into an interface vector, when in SCATTER_FORWARD mode, or vice-versa, when in SCATTER_REVERSE 321 mode. 322 323 Input parameters: 324 . pc - preconditioner context 325 . array_N - [when in SCATTER_FORWARD mode] Array to be scattered into the vector 326 . v_B - [when in SCATTER_REVERSE mode] Vector to be scattered into the array 327 328 Output parameter: 329 . array_N - [when in SCATTER_REVERSE mode] Array to receive the scattered vector 330 . v_B - [when in SCATTER_FORWARD mode] Vector to receive the scattered array 331 332 Notes: 333 The entries in the array that do not correspond to interface nodes remain unaltered. 334 */ 335 #undef __FUNCT__ 336 #define __FUNCT__ "PCISScatterArrayNToVecB" 337 PetscErrorCode PCISScatterArrayNToVecB (PetscScalar *array_N, Vec v_B, InsertMode imode, ScatterMode smode, PC pc) 338 { 339 PetscInt i, *idex; 340 PetscErrorCode ierr; 341 PetscScalar *array_B; 342 PC_IS *pcis = (PC_IS*)(pc->data); 343 344 PetscFunctionBegin; 345 ierr = VecGetArray(v_B,&array_B);CHKERRQ(ierr); 346 ierr = ISGetIndices(pcis->is_B_local,&idex);CHKERRQ(ierr); 347 348 if (smode == SCATTER_FORWARD) { 349 if (imode == INSERT_VALUES) { 350 for (i=0; i<pcis->n_B; i++) { array_B[i] = array_N[idex[i]]; } 351 } else { /* ADD_VALUES */ 352 for (i=0; i<pcis->n_B; i++) { array_B[i] += array_N[idex[i]]; } 353 } 354 } else { /* SCATTER_REVERSE */ 355 if (imode == INSERT_VALUES) { 356 for (i=0; i<pcis->n_B; i++) { array_N[idex[i]] = array_B[i]; } 357 } else { /* ADD_VALUES */ 358 for (i=0; i<pcis->n_B; i++) { array_N[idex[i]] += array_B[i]; } 359 } 360 } 361 ierr = ISRestoreIndices(pcis->is_B_local,&idex);CHKERRQ(ierr); 362 ierr = VecRestoreArray(v_B,&array_B);CHKERRQ(ierr); 363 PetscFunctionReturn(0); 364 } 365 366 /* -------------------------------------------------------------------------- */ 367 /* 368 PCISApplyInvSchur - Solves the Neumann problem related to applying the inverse of the Schur complement. 369 More precisely, solves the problem: 370 [ A_II A_IB ] [ . ] [ 0 ] 371 [ ] [ ] = [ ] 372 [ A_BI A_BB ] [ x ] [ b ] 373 374 Input parameters: 375 . pc - preconditioner context 376 . b - vector of local interface nodes (including ghosts) 377 378 Output parameters: 379 . x - vector of local interface nodes (including ghosts); returns the application of the inverse of the Schur 380 complement to b 381 . vec1_N - vector of local nodes (interior and interface, including ghosts); returns garbage (used as work space) 382 . vec2_N - vector of local nodes (interior and interface, including ghosts); returns garbage (used as work space) 383 384 */ 385 #undef __FUNCT__ 386 #define __FUNCT__ "PCISApplyInvSchur" 387 PetscErrorCode PCISApplyInvSchur (PC pc, Vec b, Vec x, Vec vec1_N, Vec vec2_N) 388 { 389 PetscErrorCode ierr; 390 PC_IS *pcis = (PC_IS*)(pc->data); 391 PetscScalar zero = 0.0; 392 393 PetscFunctionBegin; 394 /* 395 Neumann solvers. 396 Applying the inverse of the local Schur complement, i.e, solving a Neumann 397 Problem with zero at the interior nodes of the RHS and extracting the interface 398 part of the solution. inverse Schur complement is applied to b and the result 399 is stored in x. 400 */ 401 /* Setting the RHS vec1_N */ 402 ierr = VecSet(&zero,vec1_N);CHKERRQ(ierr); 403 ierr = VecScatterBegin(b,vec1_N,INSERT_VALUES,SCATTER_REVERSE,pcis->N_to_B);CHKERRQ(ierr); 404 ierr = VecScatterEnd (b,vec1_N,INSERT_VALUES,SCATTER_REVERSE,pcis->N_to_B);CHKERRQ(ierr); 405 /* Checking for consistency of the RHS */ 406 { 407 PetscTruth flg; 408 ierr = PetscOptionsHasName(PETSC_NULL,"-pc_is_check_consistency",&flg);CHKERRQ(ierr); 409 if (flg) { 410 PetscScalar average; 411 ierr = VecSum(vec1_N,&average);CHKERRQ(ierr); 412 average = average / ((PetscReal)pcis->n); 413 if (pcis->pure_neumann) { 414 ierr = PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_(pc->comm),"Subdomain %04d is floating. Average = % 1.14e\n", 415 PetscGlobalRank,PetscAbsScalar(average));CHKERRQ(ierr); 416 } else { 417 ierr = PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_(pc->comm),"Subdomain %04d is fixed. Average = % 1.14e\n", 418 PetscGlobalRank,PetscAbsScalar(average));CHKERRQ(ierr); 419 } 420 PetscViewerFlush(PETSC_VIEWER_STDOUT_(pc->comm)); 421 } 422 } 423 /* Solving the system for vec2_N */ 424 ierr = KSPSolve(pcis->ksp_N,vec1_N,vec2_N);CHKERRQ(ierr); 425 /* Extracting the local interface vector out of the solution */ 426 ierr = VecScatterBegin(vec2_N,x,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 427 ierr = VecScatterEnd (vec2_N,x,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 428 PetscFunctionReturn(0); 429 } 430 431 432 433 434 435 436 437 438 439