Actual source code: is.c

  1: /*$Id: is.c,v 1.9 2001/08/07 03:03:41 balay Exp $*/
 2:  #include src/sles/pc/impls/is/is.h

  4: /* -------------------------------------------------------------------------- */
  5: /*
  6:    PCISSetUp - 
  7: */
  8: int PCISSetUp(PC pc)
  9: {
 10:   PC_IS      *pcis = (PC_IS*)(pc->data);
 11:   Mat_IS     *matis = (Mat_IS*)pc->mat->data;
 12:   int        i, ierr;
 13:   PetscTruth flg;
 14: 
 16:   PetscTypeCompare((PetscObject)pc->mat,MATIS,&flg);
 17:   if (!flg){
 18:     SETERRQ(1,"Preconditioner type of Neumann Neumman requires matrix of type MATIS");
 19:   }

 21:   pcis->pure_neumann = matis->pure_neumann;

 23:   /*
 24:     Creating the local vector vec1_N, containing the inverse of the number
 25:     of subdomains to which each local node (either owned or ghost)
 26:     pertains. To accomplish that, we scatter local vectors of 1's to
 27:     a global vector (adding the values); scatter the result back to
 28:     local vectors and finally invert the result.
 29:   */
 30:   {
 31:     Vec    counter;
 32:     PetscScalar one=1.0, zero=0.0;
 33:     VecDuplicate(matis->x,&pcis->vec1_N);
 34:     VecDuplicate(pc->vec,&counter); /* temporary auxiliar vector */
 35:     VecSet(&zero,counter);
 36:     VecSet(&one,pcis->vec1_N);
 37:     VecScatterBegin(pcis->vec1_N,counter,ADD_VALUES,SCATTER_REVERSE,matis->ctx);
 38:     VecScatterEnd  (pcis->vec1_N,counter,ADD_VALUES,SCATTER_REVERSE,matis->ctx);
 39:     VecScatterBegin(counter,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD,matis->ctx);
 40:     VecScatterEnd  (counter,pcis->vec1_N,INSERT_VALUES,SCATTER_FORWARD,matis->ctx);
 41:     VecDestroy(counter);
 42:   }
 43:   /*
 44:     Creating local and global index sets for interior and
 45:     inteface nodes. Notice that interior nodes have D[i]==1.0.
 46:   */
 47:   {
 48:     int     n_I;
 49:     int    *idx_I_local,*idx_B_local,*idx_I_global,*idx_B_global;
 50:     PetscScalar *array;
 51:     /* Identifying interior and interface nodes, in local numbering */
 52:     VecGetSize(pcis->vec1_N,&pcis->n);
 53:     VecGetArray(pcis->vec1_N,&array);
 54:     PetscMalloc(pcis->n*sizeof(int),&idx_I_local);
 55:     PetscMalloc(pcis->n*sizeof(int),&idx_B_local);
 56:     for (i=0, pcis->n_B=0, n_I=0; i<pcis->n; i++) {
 57:       if (array[i] == 1.0) { idx_I_local[n_I]       = i; n_I++;       }
 58:       else                 { idx_B_local[pcis->n_B] = i; pcis->n_B++; }
 59:     }
 60:     /* Getting the global numbering */
 61:     idx_B_global = idx_I_local + n_I; /* Just avoiding allocating extra memory, since we have vacant space */
 62:     idx_I_global = idx_B_local + pcis->n_B;
 63:     ISLocalToGlobalMappingApply(matis->mapping,pcis->n_B,idx_B_local,idx_B_global);
 64:     ISLocalToGlobalMappingApply(matis->mapping,n_I,      idx_I_local,idx_I_global);
 65:     /* Creating the index sets. */
 66:     ISCreateGeneral(MPI_COMM_SELF,pcis->n_B,idx_B_local, &pcis->is_B_local);
 67:     ISCreateGeneral(MPI_COMM_SELF,pcis->n_B,idx_B_global,&pcis->is_B_global);
 68:     ISCreateGeneral(MPI_COMM_SELF,n_I      ,idx_I_local, &pcis->is_I_local);
 69:     ISCreateGeneral(MPI_COMM_SELF,n_I      ,idx_I_global,&pcis->is_I_global);
 70:     /* Freeing memory and restoring arrays */
 71:     PetscFree(idx_B_local);
 72:     PetscFree(idx_I_local);
 73:     VecRestoreArray(pcis->vec1_N,&array);
 74:   }

 76:   /*
 77:     Extracting the blocks A_II, A_BI, A_IB and A_BB from A. If the numbering
 78:     is such that interior nodes come first than the interface ones, we have

 80:     [           |      ]
 81:     [    A_II   | A_IB ]
 82:     A = [           |      ]
 83:     [-----------+------]
 84:     [    A_BI   | A_BB ]
 85:   */

 87:   MatGetSubMatrix(matis->A,pcis->is_I_local,pcis->is_I_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_II);
 88:   MatGetSubMatrix(matis->A,pcis->is_I_local,pcis->is_B_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_IB);
 89:   MatGetSubMatrix(matis->A,pcis->is_B_local,pcis->is_I_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_BI);
 90:   MatGetSubMatrix(matis->A,pcis->is_B_local,pcis->is_B_local,PETSC_DECIDE,MAT_INITIAL_MATRIX,&pcis->A_BB);

 92:   /*
 93:     Creating work vectors and arrays
 94:   */
 95:   /* pcis->vec1_N has already been created */
 96:   VecDuplicate(pcis->vec1_N,&pcis->vec2_N);
 97:   VecCreateSeq(PETSC_COMM_SELF,pcis->n-pcis->n_B,&pcis->vec1_D);
 98:   VecDuplicate(pcis->vec1_D,&pcis->vec2_D);
 99:   VecDuplicate(pcis->vec1_D,&pcis->vec3_D);
100:   VecCreateSeq(PETSC_COMM_SELF,pcis->n_B,&pcis->vec1_B);
101:   VecDuplicate(pcis->vec1_B,&pcis->vec2_B);
102:   VecDuplicate(pcis->vec1_B,&pcis->vec3_B);
103:   {
104:     Vec global;
105:     PCGetVector(pc,&global);
106:     VecDuplicate(global,&pcis->vec1_global);
107:   }
108:   PetscMalloc((pcis->n)*sizeof(PetscScalar),&pcis->work_N);

110:   /* Creating the scatter contexts */
111:   VecScatterCreate(pc->vec,pcis->is_I_global,pcis->vec1_D,(IS)0,&pcis->global_to_D);
112:   VecScatterCreate(pcis->vec1_N,pcis->is_B_local,pcis->vec1_B,(IS)0,&pcis->N_to_B);
113:   VecScatterCreate(pc->vec,pcis->is_B_global,pcis->vec1_B,(IS)0,&pcis->global_to_B);

115:   /* Creating scaling "matrix" D, from information in vec1_N */
116:   VecDuplicate(pcis->vec1_B,&pcis->D);
117:   VecScatterBegin(pcis->vec1_N,pcis->D,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);
118:   VecScatterEnd  (pcis->vec1_N,pcis->D,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);
119:   VecReciprocal(pcis->D);

121:   /* See historical note 01, at the bottom of this file. */

123:   /*
124:     Creating the SLES contexts for the local Dirichlet and Neumann problems.
125:   */
126:   {
127:     PC  pc_ctx;
128:     KSP ksp_ctx;
129:     /* Dirichlet */
130:     SLESCreate(PETSC_COMM_SELF,&pcis->sles_D);
131:     SLESSetOperators(pcis->sles_D,pcis->A_II,pcis->A_II,SAME_PRECONDITIONER);
132:     SLESSetOptionsPrefix(pcis->sles_D,"localD_");
133:     SLESGetKSP(pcis->sles_D,&ksp_ctx);
134:     SLESGetPC(pcis->sles_D,&pc_ctx);
135:     PCSetType(pc_ctx,PCLU);
136:     KSPSetType(ksp_ctx,KSPPREONLY);
137:     SLESSetFromOptions(pcis->sles_D);
138:     /* the vectors in the following line are dummy arguments, just telling the SLES the vector size. Values are not used */
139:     SLESSetUp(pcis->sles_D,pcis->vec1_D,pcis->vec2_D);
140:     /* Neumann */
141:     SLESCreate(PETSC_COMM_SELF,&pcis->sles_N);
142:     SLESSetOperators(pcis->sles_N,matis->A,matis->A,SAME_PRECONDITIONER);
143:     SLESSetOptionsPrefix(pcis->sles_N,"localN_");
144:     SLESGetKSP(pcis->sles_N,&ksp_ctx);
145:     SLESGetPC(pcis->sles_N,&pc_ctx);
146:     PCSetType(pc_ctx,PCLU);
147:     KSPSetType(ksp_ctx,KSPPREONLY);
148:     SLESSetFromOptions(pcis->sles_N);
149:     {
150:       PetscTruth damp_fixed,
151:                  remove_nullspace_fixed,
152:                  set_damping_factor_floating,
153:                  not_damp_floating,
154:                  not_remove_nullspace_floating;
155:       PetscReal  fixed_factor,
156:                  floating_factor;

158:       PetscOptionsGetReal(pc_ctx->prefix,"-pc_is_damp_fixed",&fixed_factor,&damp_fixed);
159:       if (!damp_fixed) { fixed_factor = 0.0; }
160:       PetscOptionsHasName(pc_ctx->prefix,"-pc_is_damp_fixed",&damp_fixed);

162:       PetscOptionsHasName(pc_ctx->prefix,"-pc_is_remove_nullspace_fixed",&remove_nullspace_fixed);

164:       PetscOptionsGetReal(pc_ctx->prefix,"-pc_is_set_damping_factor_floating",
165:                               &floating_factor,&set_damping_factor_floating);
166:       if (!set_damping_factor_floating) { floating_factor = 0.0; }
167:       PetscOptionsHasName(pc_ctx->prefix,"-pc_is_set_damping_factor_floating",&set_damping_factor_floating);
168:       if (!set_damping_factor_floating) { floating_factor = 1.e-12; }

170:       PetscOptionsHasName(pc_ctx->prefix,"-pc_is_not_damp_floating",&not_damp_floating);

172:       PetscOptionsHasName(pc_ctx->prefix,"-pc_is_not_remove_nullspace_floating",&not_remove_nullspace_floating);

174:       if (pcis->pure_neumann) {  /* floating subdomain */
175:         if (!(not_damp_floating)) {
176:           PCLUSetDamping (pc_ctx,floating_factor);
177:           PCILUSetDamping(pc_ctx,floating_factor);
178:         }
179:         if (!(not_remove_nullspace_floating)){
180:           MatNullSpace nullsp;
181:           MatNullSpaceCreate(PETSC_COMM_SELF,1,0,PETSC_NULL,&nullsp);
182:           PCNullSpaceAttach(pc_ctx,nullsp);
183:           MatNullSpaceDestroy(nullsp);
184:         }
185:       } else {  /* fixed subdomain */
186:         if (damp_fixed) {
187:           PCLUSetDamping (pc_ctx,fixed_factor);
188:           PCILUSetDamping(pc_ctx,fixed_factor);
189:         }
190:         if (remove_nullspace_fixed) {
191:           MatNullSpace nullsp;
192:           MatNullSpaceCreate(PETSC_COMM_SELF,1,0,PETSC_NULL,&nullsp);
193:           PCNullSpaceAttach(pc_ctx,nullsp);
194:           MatNullSpaceDestroy(nullsp);
195:         }
196:       }
197:     }
198:     /* the vectors in the following line are dummy arguments, just telling the SLES the vector size. Values are not used */
199:     SLESSetUp(pcis->sles_N,pcis->vec1_N,pcis->vec2_N);
200:   }

202:   ISLocalToGlobalMappingGetInfo(((Mat_IS*)(pc->mat->data))->mapping,&(pcis->n_neigh),&(pcis->neigh),
203:                                        &(pcis->n_shared),&(pcis->shared));
204:   pcis->ISLocalToGlobalMappingGetInfoWasCalled = PETSC_TRUE;

206:   return(0);
207: }

209: /* -------------------------------------------------------------------------- */
210: /*
211:    PCISDestroy -
212: */
213: int PCISDestroy(PC pc)
214: {
215:   PC_IS *pcis = (PC_IS*)(pc->data);
216:   int   ierr;


220:   if (pcis->is_B_local)  {ISDestroy(pcis->is_B_local);}
221:   if (pcis->is_I_local)  {ISDestroy(pcis->is_I_local);}
222:   if (pcis->is_B_global) {ISDestroy(pcis->is_B_global);}
223:   if (pcis->is_I_global) {ISDestroy(pcis->is_I_global);}
224:   if (pcis->A_II)        {MatDestroy(pcis->A_II);}
225:   if (pcis->A_IB)        {MatDestroy(pcis->A_IB);}
226:   if (pcis->A_BI)        {MatDestroy(pcis->A_BI);}
227:   if (pcis->A_BB)        {MatDestroy(pcis->A_BB);}
228:   if (pcis->D)           {VecDestroy(pcis->D);}
229:   if (pcis->sles_N)      {SLESDestroy(pcis->sles_N);}
230:   if (pcis->sles_D)      {SLESDestroy(pcis->sles_D);}
231:   if (pcis->vec1_N)      {VecDestroy(pcis->vec1_N);}
232:   if (pcis->vec2_N)      {VecDestroy(pcis->vec2_N);}
233:   if (pcis->vec1_D)      {VecDestroy(pcis->vec1_D);}
234:   if (pcis->vec2_D)      {VecDestroy(pcis->vec2_D);}
235:   if (pcis->vec3_D)      {VecDestroy(pcis->vec3_D);}
236:   if (pcis->vec1_B)      {VecDestroy(pcis->vec1_B);}
237:   if (pcis->vec2_B)      {VecDestroy(pcis->vec2_B);}
238:   if (pcis->vec3_B)      {VecDestroy(pcis->vec3_B);}
239:   if (pcis->vec1_global) {VecDestroy(pcis->vec1_global);}
240:   if (pcis->work_N)      {PetscFree(pcis->work_N);}
241:   if (pcis->global_to_D) {VecScatterDestroy(pcis->global_to_D);}
242:   if (pcis->N_to_B)      {VecScatterDestroy(pcis->N_to_B);}
243:   if (pcis->global_to_B) {VecScatterDestroy(pcis->global_to_B);}
244:   if (pcis->ISLocalToGlobalMappingGetInfoWasCalled) {
245:     ISLocalToGlobalMappingRestoreInfo((ISLocalToGlobalMapping)0,&(pcis->n_neigh),&(pcis->neigh),&(pcis->n_shared),&(pcis->shared));
246:   }

248:   return(0);
249: }

251: /* -------------------------------------------------------------------------- */
252: /*
253:    PCISCreate - 
254: */
255: int PCISCreate(PC pc)
256: {
257:   PC_IS *pcis = (PC_IS*)(pc->data);


261:   pcis->is_B_local  = 0;
262:   pcis->is_I_local  = 0;
263:   pcis->is_B_global = 0;
264:   pcis->is_I_global = 0;
265:   pcis->A_II        = 0;
266:   pcis->A_IB        = 0;
267:   pcis->A_BI        = 0;
268:   pcis->A_BB        = 0;
269:   pcis->D           = 0;
270:   pcis->sles_N      = 0;
271:   pcis->sles_D      = 0;
272:   pcis->vec1_N      = 0;
273:   pcis->vec2_N      = 0;
274:   pcis->vec1_D      = 0;
275:   pcis->vec2_D      = 0;
276:   pcis->vec3_D      = 0;
277:   pcis->vec1_B      = 0;
278:   pcis->vec2_B      = 0;
279:   pcis->vec3_B      = 0;
280:   pcis->vec1_global = 0;
281:   pcis->work_N      = 0;
282:   pcis->global_to_D = 0;
283:   pcis->N_to_B      = 0;
284:   pcis->global_to_B = 0;
285:   pcis->ISLocalToGlobalMappingGetInfoWasCalled = PETSC_FALSE;

287:   return(0);
288: }

290: /* -------------------------------------------------------------------------- */
291: /*
292:    PCISApplySchur -

294:    Input parameters:
295: .  pc - preconditioner context
296: .  v - vector to which the Schur complement is to be applied (it is NOT modified inside this function, UNLESS vec2_B is null)

298:    Output parameters:
299: .  vec1_B - result of Schur complement applied to chunk
300: .  vec2_B - garbage (used as work space), or null (and v is used as workspace)
301: .  vec1_D - garbage (used as work space)
302: .  vec2_D - garbage (used as work space)

304: */
305: int PCISApplySchur(PC pc, Vec v, Vec vec1_B, Vec vec2_B, Vec vec1_D, Vec vec2_D)
306: {
307:   int    ierr, its;
308:   PetscScalar m_one = -1.0;
309:   PC_IS  *pcis = (PC_IS*)(pc->data);


313:   if (vec2_B == (Vec)0) { vec2_B = v; }

315:   MatMult(pcis->A_BB,v,vec1_B);
316:   MatMult(pcis->A_IB,v,vec1_D);
317:   SLESSolve(pcis->sles_D,vec1_D,vec2_D,&its);
318:   MatMult(pcis->A_BI,vec2_D,vec2_B);
319:   VecAXPY(&m_one,vec2_B,vec1_B);

321:   return(0);
322: }

324: /* -------------------------------------------------------------------------- */
325: /*
326:    PCISScatterArrayNToVecB - Scatters interface node values from a big array (of all local nodes, interior or interface,
327:    including ghosts) into an interface vector, when in SCATTER_FORWARD mode, or vice-versa, when in SCATTER_REVERSE
328:    mode.

330:    Input parameters:
331: .  pc - preconditioner context
332: .  array_N - [when in SCATTER_FORWARD mode] Array to be scattered into the vector
333: .  v_B - [when in SCATTER_REVERSE mode] Vector to be scattered into the array

335:    Output parameter:
336: .  array_N - [when in SCATTER_REVERSE mode] Array to receive the scattered vector
337: .  v_B - [when in SCATTER_FORWARD mode] Vector to receive the scattered array

339:    Notes:
340:    The entries in the array that do not correspond to interface nodes remain unaltered.
341: */
342: int PCISScatterArrayNToVecB (PetscScalar *array_N, Vec v_B, InsertMode imode, ScatterMode smode, PC pc)
343: {
344:   int    i, ierr, *index;
345:   PetscScalar *array_B;
346:   PC_IS  *pcis = (PC_IS*)(pc->data);


350:   VecGetArray(v_B,&array_B);
351:   ISGetIndices(pcis->is_B_local,&index);

353:   if (smode == SCATTER_FORWARD) {
354:     if (imode == INSERT_VALUES) {
355:       for (i=0; i<pcis->n_B; i++) { array_B[i]  = array_N[index[i]]; }
356:     } else {  /* ADD_VALUES */
357:       for (i=0; i<pcis->n_B; i++) { array_B[i] += array_N[index[i]]; }
358:     }
359:   } else {  /* SCATTER_REVERSE */
360:     if (imode == INSERT_VALUES) {
361:       for (i=0; i<pcis->n_B; i++) { array_N[index[i]]  = array_B[i]; }
362:     } else {  /* ADD_VALUES */
363:       for (i=0; i<pcis->n_B; i++) { array_N[index[i]] += array_B[i]; }
364:     }
365:   }

367:   ISRestoreIndices(pcis->is_B_local,&index);
368:   VecRestoreArray(v_B,&array_B);

370:   return(0);
371: }

373: /* -------------------------------------------------------------------------- */
374: /*
375:    PCISApplyInvSchur - Solves the Neumann problem related to applying the inverse of the Schur complement.
376:    More precisely, solves the problem:
377:                                         [ A_II  A_IB ] [ . ]   [ 0 ]
378:                                         [            ] [   ] = [   ]
379:                                         [ A_BI  A_BB ] [ x ]   [ b ]

381:    Input parameters:
382: .  pc - preconditioner context
383: .  b - vector of local interface nodes (including ghosts)

385:    Output parameters:
386: .  x - vector of local interface nodes (including ghosts); returns the application of the inverse of the Schur
387:        complement to b
388: .  vec1_N - vector of local nodes (interior and interface, including ghosts); returns garbage (used as work space)
389: .  vec2_N - vector of local nodes (interior and interface, including ghosts); returns garbage (used as work space)

391: */
392: int PCISApplyInvSchur (PC pc, Vec b, Vec x, Vec vec1_N, Vec vec2_N)
393: {
394:   int    ierr, its;
395:   PC_IS  *pcis = (PC_IS*)(pc->data);
396:   PetscScalar zero  = 0.0;


400:   /*
401:     Neumann solvers. 
402:     Applying the inverse of the local Schur complement, i.e, solving a Neumann
403:     Problem with zero at the interior nodes of the RHS and extracting the interface
404:     part of the solution. inverse Schur complement is applied to b and the result
405:     is stored in x.
406:   */
407:   /* Setting the RHS vec1_N */
408:   VecSet(&zero,vec1_N);
409:   VecScatterBegin(b,vec1_N,INSERT_VALUES,SCATTER_REVERSE,pcis->N_to_B);
410:   VecScatterEnd  (b,vec1_N,INSERT_VALUES,SCATTER_REVERSE,pcis->N_to_B);
411:   /* Checking for consistency of the RHS */
412:   {
413:     PetscTruth flg;
414:     PetscOptionsHasName(PETSC_NULL,"-check_consistency",&flg);
415:     if (flg) {
416:       PetscScalar average;
417:       VecSum(vec1_N,&average);
418:       average = average / ((PetscReal)pcis->n);
419:       if (pcis->pure_neumann) {
420:         PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_(pc->comm),"Subdomain %04d is floating. Average = % 1.14en",
421:                                              PetscGlobalRank,PetscAbsScalar(average));
422:       } else {
423:         PetscViewerASCIISynchronizedPrintf(PETSC_VIEWER_STDOUT_(pc->comm),"Subdomain %04d is fixed.    Average = % 1.14en",
424:                                              PetscGlobalRank,PetscAbsScalar(average));
425:       }
426:       PetscViewerFlush(PETSC_VIEWER_STDOUT_(pc->comm));
427:     }
428:   }
429:   /* Solving the system for vec2_N */
430:   SLESSolve(pcis->sles_N,vec1_N,vec2_N,&its);
431:   /* Extracting the local interface vector out of the solution */
432:   VecScatterBegin(vec2_N,x,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);
433:   VecScatterEnd  (vec2_N,x,INSERT_VALUES,SCATTER_FORWARD,pcis->N_to_B);

435:   return(0);
436: }