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 int 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 int n_I; 52 int *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(int),&idx_I_local);CHKERRQ(ierr); 58 ierr = PetscMalloc(pcis->n*sizeof(int),&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 = PCLUSetDamping (pc_ctx,floating_factor);CHKERRQ(ierr); 173 ierr = PCILUSetDamping(pc_ctx,floating_factor);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 = PCLUSetDamping (pc_ctx,fixed_factor);CHKERRQ(ierr); 184 ierr = PCILUSetDamping(pc_ctx,fixed_factor);CHKERRQ(ierr); 185 } 186 if (remove_nullspace_fixed) { 187 MatNullSpace nullsp; 188 ierr = MatNullSpaceCreate(PETSC_COMM_SELF,PETSC_TRUE,0,PETSC_NULL,&nullsp);CHKERRQ(ierr); 189 ierr = KSPSetNullSpace(pcis->ksp_N,nullsp);CHKERRQ(ierr); 190 ierr = MatNullSpaceDestroy(nullsp);CHKERRQ(ierr); 191 } 192 } 193 } 194 /* the vectors in the following line are dummy arguments, just telling the KSP the vector size. Values are not used */ 195 ierr = KSPSetUp(pcis->ksp_N);CHKERRQ(ierr); 196 } 197 198 ierr = ISLocalToGlobalMappingGetInfo(((Mat_IS*)(pc->mat->data))->mapping,&(pcis->n_neigh),&(pcis->neigh),&(pcis->n_shared),&(pcis->shared));CHKERRQ(ierr); 199 pcis->ISLocalToGlobalMappingGetInfoWasCalled = PETSC_TRUE; 200 201 PetscFunctionReturn(0); 202 } 203 204 /* -------------------------------------------------------------------------- */ 205 /* 206 PCISDestroy - 207 */ 208 #undef __FUNCT__ 209 #define __FUNCT__ "PCISDestroy" 210 PetscErrorCode PCISDestroy(PC pc) 211 { 212 PC_IS *pcis = (PC_IS*)(pc->data); 213 PetscErrorCode ierr; 214 215 PetscFunctionBegin; 216 217 if (pcis->is_B_local) {ierr = ISDestroy(pcis->is_B_local);CHKERRQ(ierr);} 218 if (pcis->is_I_local) {ierr = ISDestroy(pcis->is_I_local);CHKERRQ(ierr);} 219 if (pcis->is_B_global) {ierr = ISDestroy(pcis->is_B_global);CHKERRQ(ierr);} 220 if (pcis->is_I_global) {ierr = ISDestroy(pcis->is_I_global);CHKERRQ(ierr);} 221 if (pcis->A_II) {ierr = MatDestroy(pcis->A_II);CHKERRQ(ierr);} 222 if (pcis->A_IB) {ierr = MatDestroy(pcis->A_IB);CHKERRQ(ierr);} 223 if (pcis->A_BI) {ierr = MatDestroy(pcis->A_BI);CHKERRQ(ierr);} 224 if (pcis->A_BB) {ierr = MatDestroy(pcis->A_BB);CHKERRQ(ierr);} 225 if (pcis->D) {ierr = VecDestroy(pcis->D);CHKERRQ(ierr);} 226 if (pcis->ksp_N) {ierr = KSPDestroy(pcis->ksp_N);CHKERRQ(ierr);} 227 if (pcis->ksp_D) {ierr = KSPDestroy(pcis->ksp_D);CHKERRQ(ierr);} 228 if (pcis->vec1_N) {ierr = VecDestroy(pcis->vec1_N);CHKERRQ(ierr);} 229 if (pcis->vec2_N) {ierr = VecDestroy(pcis->vec2_N);CHKERRQ(ierr);} 230 if (pcis->vec1_D) {ierr = VecDestroy(pcis->vec1_D);CHKERRQ(ierr);} 231 if (pcis->vec2_D) {ierr = VecDestroy(pcis->vec2_D);CHKERRQ(ierr);} 232 if (pcis->vec3_D) {ierr = VecDestroy(pcis->vec3_D);CHKERRQ(ierr);} 233 if (pcis->vec1_B) {ierr = VecDestroy(pcis->vec1_B);CHKERRQ(ierr);} 234 if (pcis->vec2_B) {ierr = VecDestroy(pcis->vec2_B);CHKERRQ(ierr);} 235 if (pcis->vec3_B) {ierr = VecDestroy(pcis->vec3_B);CHKERRQ(ierr);} 236 if (pcis->vec1_global) {ierr = VecDestroy(pcis->vec1_global);CHKERRQ(ierr);} 237 if (pcis->work_N) {ierr = PetscFree(pcis->work_N);CHKERRQ(ierr);} 238 if (pcis->global_to_D) {ierr = VecScatterDestroy(pcis->global_to_D);CHKERRQ(ierr);} 239 if (pcis->N_to_B) {ierr = VecScatterDestroy(pcis->N_to_B);CHKERRQ(ierr);} 240 if (pcis->global_to_B) {ierr = VecScatterDestroy(pcis->global_to_B);CHKERRQ(ierr);} 241 if (pcis->ISLocalToGlobalMappingGetInfoWasCalled) { 242 ierr = ISLocalToGlobalMappingRestoreInfo((ISLocalToGlobalMapping)0,&(pcis->n_neigh),&(pcis->neigh),&(pcis->n_shared),&(pcis->shared));CHKERRQ(ierr); 243 } 244 245 PetscFunctionReturn(0); 246 } 247 248 /* -------------------------------------------------------------------------- */ 249 /* 250 PCISCreate - 251 */ 252 #undef __FUNCT__ 253 #define __FUNCT__ "PCISCreate" 254 PetscErrorCode PCISCreate(PC pc) 255 { 256 PC_IS *pcis = (PC_IS*)(pc->data); 257 258 PetscFunctionBegin; 259 260 pcis->is_B_local = 0; 261 pcis->is_I_local = 0; 262 pcis->is_B_global = 0; 263 pcis->is_I_global = 0; 264 pcis->A_II = 0; 265 pcis->A_IB = 0; 266 pcis->A_BI = 0; 267 pcis->A_BB = 0; 268 pcis->D = 0; 269 pcis->ksp_N = 0; 270 pcis->ksp_D = 0; 271 pcis->vec1_N = 0; 272 pcis->vec2_N = 0; 273 pcis->vec1_D = 0; 274 pcis->vec2_D = 0; 275 pcis->vec3_D = 0; 276 pcis->vec1_B = 0; 277 pcis->vec2_B = 0; 278 pcis->vec3_B = 0; 279 pcis->vec1_global = 0; 280 pcis->work_N = 0; 281 pcis->global_to_D = 0; 282 pcis->N_to_B = 0; 283 pcis->global_to_B = 0; 284 pcis->ISLocalToGlobalMappingGetInfoWasCalled = PETSC_FALSE; 285 286 PetscFunctionReturn(0); 287 } 288 289 /* -------------------------------------------------------------------------- */ 290 /* 291 PCISApplySchur - 292 293 Input parameters: 294 . pc - preconditioner context 295 . v - vector to which the Schur complement is to be applied (it is NOT modified inside this function, UNLESS vec2_B is null) 296 297 Output parameters: 298 . vec1_B - result of Schur complement applied to chunk 299 . vec2_B - garbage (used as work space), or null (and v is used as workspace) 300 . vec1_D - garbage (used as work space) 301 . vec2_D - garbage (used as work space) 302 303 */ 304 #undef __FUNCT__ 305 #define __FUNCT__ "PCIterSuApplySchur" 306 PetscErrorCode PCISApplySchur(PC pc, Vec v, Vec vec1_B, Vec vec2_B, Vec vec1_D, Vec vec2_D) 307 { 308 PetscErrorCode ierr; 309 PetscScalar m_one = -1.0; 310 PC_IS *pcis = (PC_IS*)(pc->data); 311 312 PetscFunctionBegin; 313 314 if (vec2_B == (Vec)0) { vec2_B = v; } 315 316 ierr = MatMult(pcis->A_BB,v,vec1_B);CHKERRQ(ierr); 317 ierr = MatMult(pcis->A_IB,v,vec1_D);CHKERRQ(ierr); 318 ierr = KSPSolve(pcis->ksp_D,vec1_D,vec2_D);CHKERRQ(ierr); 319 ierr = MatMult(pcis->A_BI,vec2_D,vec2_B);CHKERRQ(ierr); 320 ierr = VecAXPY(&m_one,vec2_B,vec1_B);CHKERRQ(ierr); 321 322 PetscFunctionReturn(0); 323 } 324 325 /* -------------------------------------------------------------------------- */ 326 /* 327 PCISScatterArrayNToVecB - Scatters interface node values from a big array (of all local nodes, interior or interface, 328 including ghosts) into an interface vector, when in SCATTER_FORWARD mode, or vice-versa, when in SCATTER_REVERSE 329 mode. 330 331 Input parameters: 332 . pc - preconditioner context 333 . array_N - [when in SCATTER_FORWARD mode] Array to be scattered into the vector 334 . v_B - [when in SCATTER_REVERSE mode] Vector to be scattered into the array 335 336 Output parameter: 337 . array_N - [when in SCATTER_REVERSE mode] Array to receive the scattered vector 338 . v_B - [when in SCATTER_FORWARD mode] Vector to receive the scattered array 339 340 Notes: 341 The entries in the array that do not correspond to interface nodes remain unaltered. 342 */ 343 #undef __FUNCT__ 344 #define __FUNCT__ "PCISScatterArrayNToVecB" 345 PetscErrorCode PCISScatterArrayNToVecB (PetscScalar *array_N, Vec v_B, InsertMode imode, ScatterMode smode, PC pc) 346 { 347 int i, *idex; 348 PetscErrorCode ierr; 349 PetscScalar *array_B; 350 PC_IS *pcis = (PC_IS*)(pc->data); 351 352 PetscFunctionBegin; 353 354 ierr = VecGetArray(v_B,&array_B);CHKERRQ(ierr); 355 ierr = ISGetIndices(pcis->is_B_local,&idex);CHKERRQ(ierr); 356 357 if (smode == SCATTER_FORWARD) { 358 if (imode == INSERT_VALUES) { 359 for (i=0; i<pcis->n_B; i++) { array_B[i] = array_N[idex[i]]; } 360 } else { /* ADD_VALUES */ 361 for (i=0; i<pcis->n_B; i++) { array_B[i] += array_N[idex[i]]; } 362 } 363 } else { /* SCATTER_REVERSE */ 364 if (imode == INSERT_VALUES) { 365 for (i=0; i<pcis->n_B; i++) { array_N[idex[i]] = array_B[i]; } 366 } else { /* ADD_VALUES */ 367 for (i=0; i<pcis->n_B; i++) { array_N[idex[i]] += array_B[i]; } 368 } 369 } 370 371 ierr = ISRestoreIndices(pcis->is_B_local,&idex);CHKERRQ(ierr); 372 ierr = VecRestoreArray(v_B,&array_B);CHKERRQ(ierr); 373 374 PetscFunctionReturn(0); 375 } 376 377 /* -------------------------------------------------------------------------- */ 378 /* 379 PCISApplyInvSchur - Solves the Neumann problem related to applying the inverse of the Schur complement. 380 More precisely, solves the problem: 381 [ A_II A_IB ] [ . ] [ 0 ] 382 [ ] [ ] = [ ] 383 [ A_BI A_BB ] [ x ] [ b ] 384 385 Input parameters: 386 . pc - preconditioner context 387 . b - vector of local interface nodes (including ghosts) 388 389 Output parameters: 390 . x - vector of local interface nodes (including ghosts); returns the application of the inverse of the Schur 391 complement to b 392 . vec1_N - vector of local nodes (interior and interface, including ghosts); returns garbage (used as work space) 393 . vec2_N - vector of local nodes (interior and interface, including ghosts); returns garbage (used as work space) 394 395 */ 396 #undef __FUNCT__ 397 #define __FUNCT__ "PCISApplyInvSchur" 398 PetscErrorCode PCISApplyInvSchur (PC pc, Vec b, Vec x, Vec vec1_N, Vec vec2_N) 399 { 400 PetscErrorCode ierr; 401 PC_IS *pcis = (PC_IS*)(pc->data); 402 PetscScalar zero = 0.0; 403 404 PetscFunctionBegin; 405 406 /* 407 Neumann solvers. 408 Applying the inverse of the local Schur complement, i.e, solving a Neumann 409 Problem with zero at the interior nodes of the RHS and extracting the interface 410 part of the solution. inverse Schur complement is applied to b and the result 411 is stored in x. 412 */ 413 /* Setting the RHS vec1_N */ 414 ierr = VecSet(&zero,vec1_N);CHKERRQ(ierr); 415 ierr = VecScatterBegin(b,vec1_N,INSERT_VALUES,SCATTER_REVERSE,pcis->N_to_B);CHKERRQ(ierr); 416 ierr = VecScatterEnd (b,vec1_N,INSERT_VALUES,SCATTER_REVERSE,pcis->N_to_B);CHKERRQ(ierr); 417 /* Checking for consistency of the RHS */ 418 { 419 PetscTruth flg; 420 ierr = PetscOptionsHasName(PETSC_NULL,"-pc_is_check_consistency",&flg);CHKERRQ(ierr); 421 if (flg) { 422 PetscScalar average; 423 ierr = VecSum(vec1_N,&average);CHKERRQ(ierr); 424 average = average / ((PetscReal)pcis->n); 425 if (pcis->pure_neumann) { 426 ierr = PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_(pc->comm),"Subdomain %04d is floating. Average = % 1.14e\n", 427 PetscGlobalRank,PetscAbsScalar(average));CHKERRQ(ierr); 428 } else { 429 ierr = PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_(pc->comm),"Subdomain %04d is fixed. Average = % 1.14e\n", 430 PetscGlobalRank,PetscAbsScalar(average));CHKERRQ(ierr); 431 } 432 PetscViewerFlush(PETSC_VIEWER_STDOUT_(pc->comm)); 433 } 434 } 435 /* Solving the system for vec2_N */ 436 ierr = KSPSolve(pcis->ksp_N,vec1_N,vec2_N);CHKERRQ(ierr); 437 /* Extracting the local interface vector out of the solution */ 438 ierr = VecScatterBegin(vec2_N,x,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 439 ierr = VecScatterEnd (vec2_N,x,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);CHKERRQ(ierr); 440 441 PetscFunctionReturn(0); 442 } 443 444 445 446 447 448 449 450 451 452