Actual source code: ex73.c

      2: /*
      3: This example was derived from src/ksp/ksp/tutorials ex29.c

      5: Inhomogeneous Laplacian in 2D. Modeled by the partial differential equation

      7:    -div \rho grad u = f,  0 < x,y < 1,

      9: with forcing function

     11:    f = e^{-x^2/\nu} e^{-y^2/\nu}

     13: with Dirichlet boundary conditions

     15:    u = f(x,y) for x = 0, x = 1, y = 0, y = 1

     17: or pure Neumman boundary conditions.
     18: */

     20: static char help[] = "Solves 2D inhomogeneous Laplacian. Demonstates using PCTelescopeSetCoarseDM functionality of PCTelescope via a DMShell\n\n";

     22: #include <petscdm.h>
     23: #include <petscdmda.h>
     24: #include <petscdmshell.h>
     25: #include <petscksp.h>

     27: PetscErrorCode ComputeMatrix_ShellDA(KSP,Mat,Mat,void*);
     28: PetscErrorCode ComputeMatrix_DMDA(DM,Mat,Mat,void*);
     29: PetscErrorCode ComputeRHS_DMDA(DM,Vec,void*);
     30: PetscErrorCode DMShellCreate_ShellDA(DM,DM*);
     31: PetscErrorCode DMFieldScatter_ShellDA(DM,Vec,ScatterMode,DM,Vec);
     32: PetscErrorCode DMStateScatter_ShellDA(DM,ScatterMode,DM);

     34: typedef enum {DIRICHLET, NEUMANN} BCType;

     36: typedef struct {
     37:   PetscReal rho;
     38:   PetscReal nu;
     39:   BCType    bcType;
     40:   MPI_Comm  comm;
     41: } UserContext;

     43: PetscErrorCode UserContextCreate(MPI_Comm comm,UserContext **ctx)
     44: {
     45:   UserContext    *user;
     46:   const char     *bcTypes[2] = {"dirichlet","neumann"};
     47:   PetscInt       bc;

     51:   PetscCalloc1(1,&user);
     52:   user->comm = comm;
     53:   PetscOptionsBegin(comm, "", "Options for the inhomogeneous Poisson equation", "DMqq");
     54:   user->rho = 1.0;
     55:   PetscOptionsReal("-rho", "The conductivity", "ex29.c", user->rho, &user->rho, NULL);
     56:   user->nu = 0.1;
     57:   PetscOptionsReal("-nu", "The width of the Gaussian source", "ex29.c", user->nu, &user->nu, NULL);
     58:   bc = (PetscInt)DIRICHLET;
     59:   PetscOptionsEList("-bc_type","Type of boundary condition","ex29.c",bcTypes,2,bcTypes[0],&bc,NULL);
     60:   user->bcType = (BCType)bc;
     61:   PetscOptionsEnd();
     62:   *ctx = user;
     63:   return 0;
     64: }

     66: PetscErrorCode CommCoarsen(MPI_Comm comm,PetscInt number,PetscSubcomm *p)
     67: {
     68:   PetscSubcomm   psubcomm;
     70:   PetscSubcommCreate(comm,&psubcomm);
     71:   PetscSubcommSetNumber(psubcomm,number);
     72:   PetscSubcommSetType(psubcomm,PETSC_SUBCOMM_INTERLACED);
     73:   *p = psubcomm;
     74:   return 0;
     75: }

     77: PetscErrorCode CommHierarchyCreate(MPI_Comm comm,PetscInt n,PetscInt number[],PetscSubcomm pscommlist[])
     78: {
     79:   PetscInt       k;
     80:   PetscBool      view_hierarchy = PETSC_FALSE;

     83:   for (k=0; k<n; k++) {
     84:     pscommlist[k] = NULL;
     85:   }

     87:   if (n < 1) return 0;

     89:   CommCoarsen(comm,number[n-1],&pscommlist[n-1]);
     90:   for (k=n-2; k>=0; k--) {
     91:     MPI_Comm comm_k = PetscSubcommChild(pscommlist[k+1]);
     92:     if (pscommlist[k+1]->color == 0) {
     93:       CommCoarsen(comm_k,number[k],&pscommlist[k]);
     94:     }
     95:   }

     97:   PetscOptionsGetBool(NULL,NULL,"-view_hierarchy",&view_hierarchy,NULL);
     98:   if (view_hierarchy) {
     99:     PetscMPIInt size;

    101:     MPI_Comm_size(comm,&size);
    102:     PetscPrintf(comm,"level[%D] size %d\n",n,(int)size);
    103:     for (k=n-1; k>=0; k--) {
    104:       if (pscommlist[k]) {
    105:         MPI_Comm comm_k = PetscSubcommChild(pscommlist[k]);

    107:         if (pscommlist[k]->color == 0) {
    108:           MPI_Comm_size(comm_k,&size);
    109:           PetscPrintf(comm_k,"level[%D] size %d\n",k,(int)size);
    110:         }
    111:       }
    112:     }
    113:   }
    114:   return 0;
    115: }

    117: /* taken from src/ksp/pc/impls/telescope/telescope_dmda.c */
    118: static PetscErrorCode _DMDADetermineRankFromGlobalIJ_2d(PetscInt i,PetscInt j,PetscInt Mp,PetscInt Np,
    119:                                                         PetscInt start_i[],PetscInt start_j[],
    120:                                                         PetscInt span_i[],PetscInt span_j[],
    121:                                                         PetscMPIInt *_pi,PetscMPIInt *_pj,PetscMPIInt *rank_re)
    122: {
    123:   PetscInt pi,pj,n;

    126:   *rank_re = -1;
    127:   pi = pj = -1;
    128:   if (_pi) {
    129:     for (n=0; n<Mp; n++) {
    130:       if ((i >= start_i[n]) && (i < start_i[n]+span_i[n])) {
    131:         pi = n;
    132:         break;
    133:       }
    134:     }
    136:     *_pi = (PetscMPIInt)pi;
    137:   }

    139:   if (_pj) {
    140:     for (n=0; n<Np; n++) {
    141:       if ((j >= start_j[n]) && (j < start_j[n]+span_j[n])) {
    142:         pj = n;
    143:         break;
    144:       }
    145:     }
    147:     *_pj = (PetscMPIInt)pj;
    148:   }

    150:   *rank_re = (PetscMPIInt)(pi + pj * Mp);
    151:   return 0;
    152: }

    154: /* taken from src/ksp/pc/impls/telescope/telescope_dmda.c */
    155: static PetscErrorCode _DMDADetermineGlobalS0_2d(PetscMPIInt rank_re,PetscInt Mp_re,PetscInt Np_re,
    156:                                                 PetscInt range_i_re[],PetscInt range_j_re[],PetscInt *s0)
    157: {
    158:   PetscInt    i,j,start_IJ = 0;
    159:   PetscMPIInt rank_ij;

    162:   *s0 = -1;
    163:   for (j=0; j<Np_re; j++) {
    164:     for (i=0; i<Mp_re; i++) {
    165:       rank_ij = (PetscMPIInt)(i + j*Mp_re);
    166:       if (rank_ij < rank_re) {
    167:         start_IJ += range_i_re[i]*range_j_re[j];
    168:       }
    169:     }
    170:   }
    171:   *s0 = start_IJ;
    172:   return 0;
    173: }

    175: /* adapted from src/ksp/pc/impls/telescope/telescope_dmda.c */
    176: static PetscErrorCode DMDACreatePermutation_2d(DM dmrepart,DM dmf,Mat *mat)
    177: {
    179:   PetscInt       k,sum,Mp_re = 0,Np_re = 0;
    180:   PetscInt       nx,ny,sr,er,Mr,ndof;
    181:   PetscInt       i,j,location,startI[2],endI[2],lenI[2];
    182:   const PetscInt *_range_i_re = NULL,*_range_j_re = NULL;
    183:   PetscInt       *range_i_re,*range_j_re;
    184:   PetscInt       *start_i_re,*start_j_re;
    185:   MPI_Comm       comm;
    186:   Vec            V;
    187:   Mat            Pscalar;

    190:   PetscInfo(dmf,"setting up the permutation matrix (DMDA-2D)\n");
    191:   PetscObjectGetComm((PetscObject)dmf,&comm);

    193:   _range_i_re = _range_j_re = NULL;
    194:   /* Create DMDA on the child communicator */
    195:   if (dmrepart) {
    196:     DMDAGetInfo(dmrepart,NULL,NULL,NULL,NULL,&Mp_re,&Np_re,NULL,NULL,NULL,NULL,NULL,NULL,NULL);
    197:     DMDAGetOwnershipRanges(dmrepart,&_range_i_re,&_range_j_re,NULL);
    198:   }

    200:   /* note - assume rank 0 always participates */
    201:   MPI_Bcast(&Mp_re,1,MPIU_INT,0,comm);
    202:   MPI_Bcast(&Np_re,1,MPIU_INT,0,comm);

    204:   PetscCalloc1(Mp_re,&range_i_re);
    205:   PetscCalloc1(Np_re,&range_j_re);

    207:   if (_range_i_re) PetscArraycpy(range_i_re,_range_i_re,Mp_re);
    208:   if (_range_j_re) PetscArraycpy(range_j_re,_range_j_re,Np_re);

    210:   MPI_Bcast(range_i_re,Mp_re,MPIU_INT,0,comm);
    211:   MPI_Bcast(range_j_re,Np_re,MPIU_INT,0,comm);

    213:   PetscMalloc1(Mp_re,&start_i_re);
    214:   PetscMalloc1(Np_re,&start_j_re);

    216:   sum = 0;
    217:   for (k=0; k<Mp_re; k++) {
    218:     start_i_re[k] = sum;
    219:     sum += range_i_re[k];
    220:   }

    222:   sum = 0;
    223:   for (k=0; k<Np_re; k++) {
    224:     start_j_re[k] = sum;
    225:     sum += range_j_re[k];
    226:   }

    228:   /* Create permutation */
    229:   DMDAGetInfo(dmf,NULL,&nx,&ny,NULL,NULL,NULL,NULL,&ndof,NULL,NULL,NULL,NULL,NULL);
    230:   DMGetGlobalVector(dmf,&V);
    231:   VecGetSize(V,&Mr);
    232:   VecGetOwnershipRange(V,&sr,&er);
    233:   DMRestoreGlobalVector(dmf,&V);
    234:   sr = sr / ndof;
    235:   er = er / ndof;
    236:   Mr = Mr / ndof;

    238:   MatCreate(comm,&Pscalar);
    239:   MatSetSizes(Pscalar,(er-sr),(er-sr),Mr,Mr);
    240:   MatSetType(Pscalar,MATAIJ);
    241:   MatSeqAIJSetPreallocation(Pscalar,1,NULL);
    242:   MatMPIAIJSetPreallocation(Pscalar,1,NULL,1,NULL);

    244:   DMDAGetCorners(dmf,NULL,NULL,NULL,&lenI[0],&lenI[1],NULL);
    245:   DMDAGetCorners(dmf,&startI[0],&startI[1],NULL,&endI[0],&endI[1],NULL);
    246:   endI[0] += startI[0];
    247:   endI[1] += startI[1];

    249:   for (j=startI[1]; j<endI[1]; j++) {
    250:     for (i=startI[0]; i<endI[0]; i++) {
    251:       PetscMPIInt rank_ijk_re,rank_reI[] = {0,0};
    252:       PetscInt    s0_re;
    253:       PetscInt    ii,jj,local_ijk_re,mapped_ijk;
    254:       PetscInt    lenI_re[] = {0,0};

    256:       location = (i - startI[0]) + (j - startI[1])*lenI[0];
    257:       _DMDADetermineRankFromGlobalIJ_2d(i,j,Mp_re,Np_re,
    258:                                              start_i_re,start_j_re,
    259:                                              range_i_re,range_j_re,
    260:                                              &rank_reI[0],&rank_reI[1],&rank_ijk_re);

    262:       _DMDADetermineGlobalS0_2d(rank_ijk_re,Mp_re,Np_re,range_i_re,range_j_re,&s0_re);

    264:       ii = i - start_i_re[ rank_reI[0] ];
    266:       jj = j - start_j_re[ rank_reI[1] ];

    269:       lenI_re[0] = range_i_re[ rank_reI[0] ];
    270:       lenI_re[1] = range_j_re[ rank_reI[1] ];
    271:       local_ijk_re = ii + jj * lenI_re[0];
    272:       mapped_ijk = s0_re + local_ijk_re;
    273:       MatSetValue(Pscalar,sr+location,mapped_ijk,1.0,INSERT_VALUES);
    274:     }
    275:   }
    276:   MatAssemblyBegin(Pscalar,MAT_FINAL_ASSEMBLY);
    277:   MatAssemblyEnd(Pscalar,MAT_FINAL_ASSEMBLY);

    279:   *mat = Pscalar;

    281:   PetscFree(range_i_re);
    282:   PetscFree(range_j_re);
    283:   PetscFree(start_i_re);
    284:   PetscFree(start_j_re);
    285:   return 0;
    286: }

    288: /* adapted from src/ksp/pc/impls/telescope/telescope_dmda.c */
    289: static PetscErrorCode PCTelescopeSetUp_dmda_scatters(DM dmf,DM dmc)
    290: {
    291:   Vec            xred,yred,xtmp,x,xp;
    292:   VecScatter     scatter;
    293:   IS             isin;
    294:   PetscInt       m,bs,st,ed;
    295:   MPI_Comm       comm;
    296:   VecType        vectype;

    299:   PetscObjectGetComm((PetscObject)dmf,&comm);
    300:   DMCreateGlobalVector(dmf,&x);
    301:   VecGetBlockSize(x,&bs);
    302:   VecGetType(x,&vectype);

    304:   /* cannot use VecDuplicate as xp is already composed with dmf */
    305:   /*VecDuplicate(x,&xp);*/
    306:   {
    307:     PetscInt m,M;

    309:     VecGetSize(x,&M);
    310:     VecGetLocalSize(x,&m);
    311:     VecCreate(comm,&xp);
    312:     VecSetSizes(xp,m,M);
    313:     VecSetBlockSize(xp,bs);
    314:     VecSetType(xp,vectype);
    315:   }

    317:   m = 0;
    318:   xred = NULL;
    319:   yred = NULL;
    320:   if (dmc) {
    321:     DMCreateGlobalVector(dmc,&xred);
    322:     VecDuplicate(xred,&yred);
    323:     VecGetOwnershipRange(xred,&st,&ed);
    324:     ISCreateStride(comm,ed-st,st,1,&isin);
    325:     VecGetLocalSize(xred,&m);
    326:   } else {
    327:     VecGetOwnershipRange(x,&st,&ed);
    328:     ISCreateStride(comm,0,st,1,&isin);
    329:   }
    330:   ISSetBlockSize(isin,bs);
    331:   VecCreate(comm,&xtmp);
    332:   VecSetSizes(xtmp,m,PETSC_DECIDE);
    333:   VecSetBlockSize(xtmp,bs);
    334:   VecSetType(xtmp,vectype);
    335:   VecScatterCreate(x,isin,xtmp,NULL,&scatter);

    337:   PetscObjectCompose((PetscObject)dmf,"isin",(PetscObject)isin);
    338:   PetscObjectCompose((PetscObject)dmf,"scatter",(PetscObject)scatter);
    339:   PetscObjectCompose((PetscObject)dmf,"xtmp",(PetscObject)xtmp);
    340:   PetscObjectCompose((PetscObject)dmf,"xp",(PetscObject)xp);

    342:   VecDestroy(&xred);
    343:   VecDestroy(&yred);
    344:   VecDestroy(&x);
    345:   return 0;
    346: }

    348: PetscErrorCode DMCreateMatrix_ShellDA(DM dm,Mat *A)
    349: {
    350:   DM             da;
    351:   MPI_Comm       comm;
    352:   PetscMPIInt    size;
    353:   UserContext    *ctx = NULL;
    354:   PetscInt       M,N;

    357:   DMShellGetContext(dm,&da);
    358:   PetscObjectGetComm((PetscObject)da,&comm);
    359:   MPI_Comm_size(comm,&size);
    360:   DMCreateMatrix(da,A);
    361:   MatGetSize(*A,&M,&N);
    362:   PetscPrintf(comm,"[size %D] DMCreateMatrix_ShellDA (%D x %D)\n",(PetscInt)size,M,N);

    364:   DMGetApplicationContext(dm,&ctx);
    365:   if (ctx->bcType == NEUMANN) {
    366:     MatNullSpace nullspace = NULL;
    367:     PetscPrintf(comm,"[size %D] DMCreateMatrix_ShellDA: using neumann bcs\n",(PetscInt)size);

    369:     MatGetNullSpace(*A,&nullspace);
    370:     if (!nullspace) {
    371:       PetscPrintf(comm,"[size %D] DMCreateMatrix_ShellDA: operator does not have nullspace - attaching\n",(PetscInt)size);
    372:       MatNullSpaceCreate(comm,PETSC_TRUE,0,0,&nullspace);
    373:       MatSetNullSpace(*A,nullspace);
    374:       MatNullSpaceDestroy(&nullspace);
    375:     } else {
    376:       PetscPrintf(comm,"[size %D] DMCreateMatrix_ShellDA: operator already has a nullspace\n",(PetscInt)size);
    377:     }
    378:   }
    379:   return 0;
    380: }

    382: PetscErrorCode DMCreateGlobalVector_ShellDA(DM dm,Vec *x)
    383: {
    384:   DM             da;
    386:   DMShellGetContext(dm,&da);
    387:   DMCreateGlobalVector(da,x);
    388:   VecSetDM(*x,dm);
    389:   return 0;
    390: }

    392: PetscErrorCode DMCreateLocalVector_ShellDA(DM dm,Vec *x)
    393: {
    394:   DM             da;
    396:   DMShellGetContext(dm,&da);
    397:   DMCreateLocalVector(da,x);
    398:   VecSetDM(*x,dm);
    399:   return 0;
    400: }

    402: PetscErrorCode DMCoarsen_ShellDA(DM dm,MPI_Comm comm,DM *dmc)
    403: {
    405:   *dmc = NULL;
    406:   DMGetCoarseDM(dm,dmc);
    407:   if (!*dmc) {
    408:     SETERRQ(PetscObjectComm((PetscObject)dm),PETSC_ERR_SUP,"The coarse DM should never be NULL. The DM hierarchy should have already been defined");
    409:   } else {
    410:     PetscObjectReference((PetscObject)(*dmc));
    411:   }
    412:   return 0;
    413: }

    415: PetscErrorCode DMCreateInterpolation_ShellDA(DM dm1,DM dm2,Mat *mat,Vec *vec)
    416: {
    417:   DM             da1,da2;
    419:   DMShellGetContext(dm1,&da1);
    420:   DMShellGetContext(dm2,&da2);
    421:   DMCreateInterpolation(da1,da2,mat,vec);
    422:   return 0;
    423: }

    425: PetscErrorCode DMShellDASetUp_TelescopeDMScatter(DM dmf_shell,DM dmc_shell)
    426: {
    427:   Mat            P = NULL;
    428:   DM             dmf = NULL,dmc = NULL;

    431:   DMShellGetContext(dmf_shell,&dmf);
    432:   if (dmc_shell) {
    433:     DMShellGetContext(dmc_shell,&dmc);
    434:   }
    435:   DMDACreatePermutation_2d(dmc,dmf,&P);
    436:   PetscObjectCompose((PetscObject)dmf,"P",(PetscObject)P);
    437:   PCTelescopeSetUp_dmda_scatters(dmf,dmc);
    438:   PetscObjectComposeFunction((PetscObject)dmf_shell,"PCTelescopeFieldScatter",DMFieldScatter_ShellDA);
    439:   PetscObjectComposeFunction((PetscObject)dmf_shell,"PCTelescopeStateScatter",DMStateScatter_ShellDA);
    440:   return 0;
    441: }

    443: PetscErrorCode DMShellDAFieldScatter_Forward(DM dmf,Vec x,DM dmc,Vec xc)
    444: {
    445:   Mat               P = NULL;
    446:   Vec               xp = NULL,xtmp = NULL;
    447:   VecScatter        scatter = NULL;
    448:   const PetscScalar *x_array;
    449:   PetscInt          i,st,ed;

    452:   PetscObjectQuery((PetscObject)dmf,"P",(PetscObject*)&P);
    453:   PetscObjectQuery((PetscObject)dmf,"xp",(PetscObject*)&xp);
    454:   PetscObjectQuery((PetscObject)dmf,"scatter",(PetscObject*)&scatter);
    455:   PetscObjectQuery((PetscObject)dmf,"xtmp",(PetscObject*)&xtmp);

    461:   MatMultTranspose(P,x,xp);

    463:   /* pull in vector x->xtmp */
    464:   VecScatterBegin(scatter,xp,xtmp,INSERT_VALUES,SCATTER_FORWARD);
    465:   VecScatterEnd(scatter,xp,xtmp,INSERT_VALUES,SCATTER_FORWARD);

    467:   /* copy vector entries into xred */
    468:   VecGetArrayRead(xtmp,&x_array);
    469:   if (xc) {
    470:     PetscScalar *LA_xred;
    471:     VecGetOwnershipRange(xc,&st,&ed);

    473:     VecGetArray(xc,&LA_xred);
    474:     for (i=0; i<ed-st; i++) {
    475:       LA_xred[i] = x_array[i];
    476:     }
    477:     VecRestoreArray(xc,&LA_xred);
    478:   }
    479:   VecRestoreArrayRead(xtmp,&x_array);
    480:   return 0;
    481: }

    483: PetscErrorCode DMShellDAFieldScatter_Reverse(DM dmf,Vec y,DM dmc,Vec yc)
    484: {
    485:   Mat            P = NULL;
    486:   Vec            xp = NULL,xtmp = NULL;
    487:   VecScatter     scatter = NULL;
    488:   PetscScalar    *array;
    489:   PetscInt       i,st,ed;

    492:   PetscObjectQuery((PetscObject)dmf,"P",(PetscObject*)&P);
    493:   PetscObjectQuery((PetscObject)dmf,"xp",(PetscObject*)&xp);
    494:   PetscObjectQuery((PetscObject)dmf,"scatter",(PetscObject*)&scatter);
    495:   PetscObjectQuery((PetscObject)dmf,"xtmp",(PetscObject*)&xtmp);

    502:   /* return vector */
    503:   VecGetArray(xtmp,&array);
    504:   if (yc) {
    505:     const PetscScalar *LA_yred;
    506:     VecGetOwnershipRange(yc,&st,&ed);
    507:     VecGetArrayRead(yc,&LA_yred);
    508:     for (i=0; i<ed-st; i++) {
    509:       array[i] = LA_yred[i];
    510:     }
    511:     VecRestoreArrayRead(yc,&LA_yred);
    512:   }
    513:   VecRestoreArray(xtmp,&array);
    514:   VecScatterBegin(scatter,xtmp,xp,INSERT_VALUES,SCATTER_REVERSE);
    515:   VecScatterEnd(scatter,xtmp,xp,INSERT_VALUES,SCATTER_REVERSE);
    516:   MatMult(P,xp,y);
    517:   return 0;
    518: }

    520: PetscErrorCode DMFieldScatter_ShellDA(DM dmf_shell,Vec x,ScatterMode mode,DM dmc_shell,Vec xc)
    521: {
    522:   DM             dmf = NULL,dmc = NULL;

    525:   DMShellGetContext(dmf_shell,&dmf);
    526:   if (dmc_shell) {
    527:     DMShellGetContext(dmc_shell,&dmc);
    528:   }
    529:   if (mode == SCATTER_FORWARD) {
    530:     DMShellDAFieldScatter_Forward(dmf,x,dmc,xc);
    531:   } else if (mode == SCATTER_REVERSE) {
    532:     DMShellDAFieldScatter_Reverse(dmf,x,dmc,xc);
    533:   } else SETERRQ(PetscObjectComm((PetscObject)dmf_shell),PETSC_ERR_SUP,"Only mode = SCATTER_FORWARD, SCATTER_REVERSE supported");
    534:   return 0;
    535: }

    537: PetscErrorCode DMStateScatter_ShellDA(DM dmf_shell,ScatterMode mode,DM dmc_shell)
    538: {
    539:   PetscMPIInt    size_f = 0,size_c = 0;
    541:   MPI_Comm_size(PetscObjectComm((PetscObject)dmf_shell),&size_f);
    542:   if (dmc_shell) {
    543:     MPI_Comm_size(PetscObjectComm((PetscObject)dmc_shell),&size_c);
    544:   }
    545:   if (mode == SCATTER_FORWARD) {
    546:     PetscPrintf(PetscObjectComm((PetscObject)dmf_shell),"User supplied state scatter (fine [size %d]-> coarse [size %d])\n",(int)size_f,(int)size_c);
    547:   } else if (mode == SCATTER_REVERSE) {
    548:   } else SETERRQ(PetscObjectComm((PetscObject)dmf_shell),PETSC_ERR_SUP,"Only mode = SCATTER_FORWARD, SCATTER_REVERSE supported");
    549:   return 0;
    550: }

    552: PetscErrorCode DMShellCreate_ShellDA(DM da,DM *dms)
    553: {
    555:   if (da) {
    556:     DMShellCreate(PetscObjectComm((PetscObject)da),dms);
    557:     DMShellSetContext(*dms,da);
    558:     DMShellSetCreateGlobalVector(*dms,DMCreateGlobalVector_ShellDA);
    559:     DMShellSetCreateLocalVector(*dms,DMCreateLocalVector_ShellDA);
    560:     DMShellSetCreateMatrix(*dms,DMCreateMatrix_ShellDA);
    561:     DMShellSetCoarsen(*dms,DMCoarsen_ShellDA);
    562:     DMShellSetCreateInterpolation(*dms,DMCreateInterpolation_ShellDA);
    563:   } else {
    564:     *dms = NULL;
    565:   }
    566:   return 0;
    567: }

    569: PetscErrorCode DMDestroyShellDMDA(DM *_dm)
    570: {
    571:   DM             dm,da = NULL;

    574:   if (!_dm) return 0;
    575:   dm = *_dm;
    576:   if (!dm) return 0;

    578:   DMShellGetContext(dm,&da);
    579:   if (da) {
    580:     Vec        vec;
    581:     VecScatter scatter = NULL;
    582:     IS         is = NULL;
    583:     Mat        P = NULL;

    585:     PetscObjectQuery((PetscObject)da,"P",(PetscObject*)&P);
    586:     MatDestroy(&P);

    588:     vec = NULL;
    589:     PetscObjectQuery((PetscObject)da,"xp",(PetscObject*)&vec);
    590:     VecDestroy(&vec);

    592:     PetscObjectQuery((PetscObject)da,"scatter",(PetscObject*)&scatter);
    593:     VecScatterDestroy(&scatter);

    595:     vec = NULL;
    596:     PetscObjectQuery((PetscObject)da,"xtmp",(PetscObject*)&vec);
    597:     VecDestroy(&vec);

    599:     PetscObjectQuery((PetscObject)da,"isin",(PetscObject*)&is);
    600:     ISDestroy(&is);

    602:     DMDestroy(&da);
    603:   }
    604:   DMDestroy(&dm);
    605:   *_dm = NULL;
    606:   return 0;
    607: }

    609: PetscErrorCode HierarchyCreate_Basic(DM *dm_f,DM *dm_c,UserContext *ctx)
    610: {
    611:   DM             dm,dmc,dm_shell,dmc_shell;
    612:   PetscMPIInt    rank;

    615:   MPI_Comm_rank(PETSC_COMM_WORLD,&rank);
    616:   DMDACreate2d(PETSC_COMM_WORLD,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,17,17,PETSC_DECIDE,PETSC_DECIDE,1,1,0,0,&dm);
    617:   DMSetFromOptions(dm);
    618:   DMSetUp(dm);
    619:   DMDASetUniformCoordinates(dm,0,1,0,1,0,0);
    620:   DMDASetFieldName(dm,0,"Pressure");
    621:   DMShellCreate_ShellDA(dm,&dm_shell);
    622:   DMSetApplicationContext(dm_shell,ctx);

    624:   dmc = NULL;
    625:   dmc_shell = NULL;
    626:   if (rank == 0) {
    627:     DMDACreate2d(PETSC_COMM_SELF,DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,17,17,PETSC_DECIDE,PETSC_DECIDE,1,1,0,0,&dmc);
    628:     DMSetFromOptions(dmc);
    629:     DMSetUp(dmc);
    630:     DMDASetUniformCoordinates(dmc,0,1,0,1,0,0);
    631:     DMDASetFieldName(dmc,0,"Pressure");
    632:     DMShellCreate_ShellDA(dmc,&dmc_shell);
    633:     DMSetApplicationContext(dmc_shell,ctx);
    634:   }

    636:   DMSetCoarseDM(dm_shell,dmc_shell);
    637:   DMShellDASetUp_TelescopeDMScatter(dm_shell,dmc_shell);

    639:   *dm_f = dm_shell;
    640:   *dm_c = dmc_shell;
    641:   return 0;
    642: }

    644: PetscErrorCode HierarchyCreate(PetscInt *_nd,PetscInt *_nref,MPI_Comm **_cl,DM **_dl)
    645: {
    646:   PetscInt       d,k,ndecomps,ncoarsen,found,nx;
    647:   PetscInt       levelrefs,*number;
    648:   PetscSubcomm   *pscommlist;
    649:   MPI_Comm       *commlist;
    650:   DM             *dalist,*dmlist;
    651:   PetscBool      set;

    654:   ndecomps = 1;
    655:   PetscOptionsGetInt(NULL,NULL,"-ndecomps",&ndecomps,NULL);
    656:   ncoarsen = ndecomps - 1;

    659:   levelrefs = 2;
    660:   PetscOptionsGetInt(NULL,NULL,"-level_nrefs",&levelrefs,NULL);
    661:   PetscMalloc1(ncoarsen+1,&number);
    662:   for (k=0; k<ncoarsen+1; k++) {
    663:     number[k] = 2;
    664:   }
    665:   found = ncoarsen;
    666:   set = PETSC_FALSE;
    667:   PetscOptionsGetIntArray(NULL,NULL,"-level_comm_red_factor",number,&found,&set);
    668:   if (set) {
    670:   }

    672:   PetscMalloc1(ncoarsen+1,&pscommlist);
    673:   for (k=0; k<ncoarsen+1; k++) {
    674:     pscommlist[k] = NULL;
    675:   }

    677:   PetscMalloc1(ndecomps,&commlist);
    678:   for (k=0; k<ndecomps; k++) {
    679:     commlist[k] = MPI_COMM_NULL;
    680:   }
    681:   PetscMalloc1(ndecomps*levelrefs,&dalist);
    682:   PetscMalloc1(ndecomps*levelrefs,&dmlist);
    683:   for (k=0; k<ndecomps*levelrefs; k++) {
    684:     dalist[k] = NULL;
    685:     dmlist[k] = NULL;
    686:   }

    688:   CommHierarchyCreate(PETSC_COMM_WORLD,ncoarsen,number,pscommlist);
    689:   for (k=0; k<ncoarsen; k++) {
    690:     if (pscommlist[k]) {
    691:       MPI_Comm comm_k = PetscSubcommChild(pscommlist[k]);
    692:       if (pscommlist[k]->color == 0) {
    693:         PetscCommDuplicate(comm_k,&commlist[k],NULL);
    694:       }
    695:     }
    696:   }
    697:   PetscCommDuplicate(PETSC_COMM_WORLD,&commlist[ndecomps-1],NULL);

    699:   for (k=0; k<ncoarsen; k++) {
    700:     if (pscommlist[k]) {
    701:       PetscSubcommDestroy(&pscommlist[k]);
    702:     }
    703:   }

    705:   nx = 17;
    706:   PetscOptionsGetInt(NULL,NULL,"-m",&nx,NULL);
    707:   for (d=0; d<ndecomps; d++) {
    708:     DM   dmroot = NULL;
    709:     char name[PETSC_MAX_PATH_LEN];

    711:     if (commlist[d] != MPI_COMM_NULL) {
    712:       DMDACreate2d(commlist[d],DM_BOUNDARY_NONE,DM_BOUNDARY_NONE,DMDA_STENCIL_STAR,nx,nx,PETSC_DECIDE,PETSC_DECIDE,1,1,0,0,&dmroot);
    713:       DMSetUp(dmroot);
    714:       DMDASetUniformCoordinates(dmroot,0,1,0,1,0,0);
    715:       DMDASetFieldName(dmroot,0,"Pressure");
    716:       PetscSNPrintf(name,PETSC_MAX_PATH_LEN-1,"root-decomp-%D",d);
    717:       PetscObjectSetName((PetscObject)dmroot,name);
    718:       /*DMView(dmroot,PETSC_VIEWER_STDOUT_(commlist[d]));*/
    719:     }

    721:     dalist[d*levelrefs + 0] = dmroot;
    722:     for (k=1; k<levelrefs; k++) {
    723:       DM dmref = NULL;

    725:       if (commlist[d] != MPI_COMM_NULL) {
    726:         DMRefine(dalist[d*levelrefs + (k-1)],MPI_COMM_NULL,&dmref);
    727:         PetscSNPrintf(name,PETSC_MAX_PATH_LEN-1,"ref%D-decomp-%D",k,d);
    728:         PetscObjectSetName((PetscObject)dmref,name);
    729:         DMDAGetInfo(dmref,NULL,&nx,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);
    730:         /*DMView(dmref,PETSC_VIEWER_STDOUT_(commlist[d]));*/
    731:       }
    732:       dalist[d*levelrefs + k] = dmref;
    733:     }
    734:     MPI_Allreduce(MPI_IN_PLACE,&nx,1,MPIU_INT,MPI_MAX,PETSC_COMM_WORLD);
    735:   }

    737:   /* create the hierarchy of DMShell's */
    738:   for (d=0; d<ndecomps; d++) {
    739:     char name[PETSC_MAX_PATH_LEN];

    741:     UserContext *ctx = NULL;
    742:     if (commlist[d] != MPI_COMM_NULL) {
    743:       UserContextCreate(commlist[d],&ctx);
    744:       for (k=0; k<levelrefs; k++) {
    745:         DMShellCreate_ShellDA(dalist[d*levelrefs + k],&dmlist[d*levelrefs + k]);
    746:         DMSetApplicationContext(dmlist[d*levelrefs + k],ctx);
    747:         PetscSNPrintf(name,PETSC_MAX_PATH_LEN-1,"level%D-decomp-%D",k,d);
    748:         PetscObjectSetName((PetscObject)dmlist[d*levelrefs + k],name);
    749:       }
    750:     }
    751:   }

    753:   /* set all the coarse DMs */
    754:   for (k=1; k<ndecomps*levelrefs; k++) { /* skip first DM as it doesn't have a coarse representation */
    755:     DM dmfine = NULL,dmcoarse = NULL;

    757:     dmfine = dmlist[k];
    758:     dmcoarse = dmlist[k-1];
    759:     if (dmfine) {
    760:       DMSetCoarseDM(dmfine,dmcoarse);
    761:     }
    762:   }

    764:   /* do special setup on the fine DM coupling different decompositions */
    765:   for (d=1; d<ndecomps; d++) { /* skip first decomposition as it doesn't have a coarse representation */
    766:     DM dmfine = NULL,dmcoarse = NULL;

    768:     dmfine = dmlist[d*levelrefs + 0];
    769:     dmcoarse = dmlist[(d-1)*levelrefs + (levelrefs-1)];
    770:     if (dmfine) {
    771:       DMShellDASetUp_TelescopeDMScatter(dmfine,dmcoarse);
    772:     }
    773:   }

    775:   PetscFree(number);
    776:   for (k=0; k<ncoarsen; k++) {
    777:     PetscSubcommDestroy(&pscommlist[k]);
    778:   }
    779:   PetscFree(pscommlist);

    781:   if (_nd) {
    782:     *_nd = ndecomps;
    783:   }
    784:   if (_nref) {
    785:     *_nref = levelrefs;
    786:   }
    787:   if (_cl) {
    788:     *_cl = commlist;
    789:   } else {
    790:     for (k=0; k<ndecomps; k++) {
    791:       if (commlist[k] != MPI_COMM_NULL) {
    792:         PetscCommDestroy(&commlist[k]);
    793:       }
    794:     }
    795:     PetscFree(commlist);
    796:   }
    797:   if (_dl) {
    798:     *_dl = dmlist;
    799:     PetscFree(dalist);
    800:   } else {
    801:     for (k=0; k<ndecomps*levelrefs; k++) {
    802:       DMDestroy(&dmlist[k]);
    803:       DMDestroy(&dalist[k]);
    804:     }
    805:     PetscFree(dmlist);
    806:     PetscFree(dalist);
    807:   }
    808:   return 0;
    809: }

    811: PetscErrorCode test_hierarchy(void)
    812: {
    813:   PetscInt       d,k,nd,nref;
    814:   MPI_Comm       *comms;
    815:   DM             *dms;

    818:   HierarchyCreate(&nd,&nref,&comms,&dms);

    820:   /* destroy user context */
    821:   for (d=0; d<nd; d++) {
    822:     DM first = dms[d*nref+0];

    824:     if (first) {
    825:       UserContext *ctx = NULL;

    827:       DMGetApplicationContext(first,&ctx);
    828:       if (ctx) PetscFree(ctx);
    829:       DMSetApplicationContext(first,NULL);
    830:     }
    831:     for (k=1; k<nref; k++) {
    832:       DM dm = dms[d*nref+k];
    833:       if (dm) {
    834:         DMSetApplicationContext(dm,NULL);
    835:       }
    836:     }
    837:   }

    839:   /* destroy DMs */
    840:   for (k=0; k<nd*nref; k++) {
    841:     if (dms[k]) {
    842:       DMDestroyShellDMDA(&dms[k]);
    843:     }
    844:   }
    845:   PetscFree(dms);

    847:   /* destroy communicators */
    848:   for (k=0; k<nd; k++) {
    849:     if (comms[k] != MPI_COMM_NULL) {
    850:       PetscCommDestroy(&comms[k]);
    851:     }
    852:   }
    853:   PetscFree(comms);
    854:   return 0;
    855: }

    857: PetscErrorCode test_basic(void)
    858: {
    859:   DM             dmF,dmdaF = NULL,dmC = NULL;
    860:   Mat            A;
    861:   Vec            x,b;
    862:   KSP            ksp;
    863:   PC             pc;
    864:   UserContext    *user = NULL;

    867:   UserContextCreate(PETSC_COMM_WORLD,&user);
    868:   HierarchyCreate_Basic(&dmF,&dmC,user);
    869:   DMShellGetContext(dmF,&dmdaF);

    871:   DMCreateMatrix(dmF,&A);
    872:   DMCreateGlobalVector(dmF,&x);
    873:   DMCreateGlobalVector(dmF,&b);
    874:   ComputeRHS_DMDA(dmdaF,b,user);

    876:   KSPCreate(PETSC_COMM_WORLD,&ksp);
    877:   KSPSetComputeOperators(ksp,ComputeMatrix_ShellDA,user);
    878:   /*KSPSetOperators(ksp,A,A);*/
    879:   KSPSetDM(ksp,dmF);
    880:   KSPSetDMActive(ksp,PETSC_TRUE);
    881:   KSPSetFromOptions(ksp);
    882:   KSPGetPC(ksp,&pc);
    883:   PCTelescopeSetUseCoarseDM(pc,PETSC_TRUE);

    885:   KSPSolve(ksp,b,x);

    887:   if (dmC) {
    888:     DMDestroyShellDMDA(&dmC);
    889:   }
    890:   DMDestroyShellDMDA(&dmF);
    891:   KSPDestroy(&ksp);
    892:   MatDestroy(&A);
    893:   VecDestroy(&b);
    894:   VecDestroy(&x);
    895:   PetscFree(user);
    896:   return 0;
    897: }

    899: PetscErrorCode test_mg(void)
    900: {
    901:   DM             dmF,dmdaF = NULL,*dms = NULL;
    902:   Mat            A;
    903:   Vec            x,b;
    904:   KSP            ksp;
    905:   PetscInt       k,d,nd,nref;
    906:   MPI_Comm       *comms = NULL;
    907:   UserContext    *user = NULL;

    910:   HierarchyCreate(&nd,&nref,&comms,&dms);
    911:   dmF = dms[nd*nref-1];

    913:   DMShellGetContext(dmF,&dmdaF);
    914:   DMGetApplicationContext(dmF,&user);

    916:   DMCreateMatrix(dmF,&A);
    917:   DMCreateGlobalVector(dmF,&x);
    918:   DMCreateGlobalVector(dmF,&b);
    919:   ComputeRHS_DMDA(dmdaF,b,user);

    921:   KSPCreate(PETSC_COMM_WORLD,&ksp);
    922:   KSPSetComputeOperators(ksp,ComputeMatrix_ShellDA,user);
    923:   /*KSPSetOperators(ksp,A,A);*/
    924:   KSPSetDM(ksp,dmF);
    925:   KSPSetDMActive(ksp,PETSC_TRUE);
    926:   KSPSetFromOptions(ksp);

    928:   KSPSolve(ksp,b,x);

    930:   for (d=0; d<nd; d++) {
    931:     DM first = dms[d*nref+0];

    933:     if (first) {
    934:       UserContext *ctx = NULL;

    936:       DMGetApplicationContext(first,&ctx);
    937:       if (ctx) PetscFree(ctx);
    938:       DMSetApplicationContext(first,NULL);
    939:     }
    940:     for (k=1; k<nref; k++) {
    941:       DM dm = dms[d*nref+k];
    942:       if (dm) {
    943:         DMSetApplicationContext(dm,NULL);
    944:       }
    945:     }
    946:   }

    948:   for (k=0; k<nd*nref; k++) {
    949:     if (dms[k]) {
    950:       DMDestroyShellDMDA(&dms[k]);
    951:     }
    952:   }
    953:   PetscFree(dms);

    955:   KSPDestroy(&ksp);
    956:   MatDestroy(&A);
    957:   VecDestroy(&b);
    958:   VecDestroy(&x);

    960:   for (k=0; k<nd; k++) {
    961:     if (comms[k] != MPI_COMM_NULL) {
    962:       PetscCommDestroy(&comms[k]);
    963:     }
    964:   }
    965:   PetscFree(comms);
    966:   return 0;
    967: }

    969: int main(int argc,char **argv)
    970: {
    971:   PetscInt       test_id = 0;

    973:   PetscInitialize(&argc,&argv,(char*)0,help);
    974:   PetscOptionsGetInt(NULL,NULL,"-tid",&test_id,NULL);
    975:   switch (test_id) {
    976:   case 0:
    977:     test_basic();
    978:       break;
    979:   case 1:
    980:     test_hierarchy();
    981:       break;
    982:   case 2:
    983:     test_mg();
    984:       break;
    985:   default:
    986:     SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_SUP,"-tid must be 0,1,2");
    987:   }
    988:   PetscFinalize();
    989:   return 0;
    990: }

    992: PetscErrorCode ComputeRHS_DMDA(DM da,Vec b,void *ctx)
    993: {
    994:   UserContext    *user = (UserContext*)ctx;
    995:   PetscInt       i,j,mx,my,xm,ym,xs,ys;
    996:   PetscScalar    Hx,Hy;
    997:   PetscScalar    **array;
    998:   PetscBool      isda = PETSC_FALSE;

    1001:   PetscObjectTypeCompare((PetscObject)da,DMDA,&isda);
    1003:   DMDAGetInfo(da,NULL,&mx,&my,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);
    1004:   Hx   = 1.0 / (PetscReal)(mx-1);
    1005:   Hy   = 1.0 / (PetscReal)(my-1);
    1006:   DMDAGetCorners(da,&xs,&ys,NULL,&xm,&ym,NULL);
    1007:   DMDAVecGetArray(da,b,&array);
    1008:   for (j=ys; j<ys+ym; j++) {
    1009:     for (i=xs; i<xs+xm; i++) {
    1010:       array[j][i] = PetscExpScalar(-((PetscReal)i*Hx)*((PetscReal)i*Hx)/user->nu)*PetscExpScalar(-((PetscReal)j*Hy)*((PetscReal)j*Hy)/user->nu)*Hx*Hy;
    1011:     }
    1012:   }
    1013:   DMDAVecRestoreArray(da, b, &array);
    1014:   VecAssemblyBegin(b);
    1015:   VecAssemblyEnd(b);

    1017:   /* force right hand side to be consistent for singular matrix */
    1018:   /* note this is really a hack, normally the model would provide you with a consistent right handside */
    1019:   if (user->bcType == NEUMANN) {
    1020:     MatNullSpace nullspace;

    1022:     MatNullSpaceCreate(PETSC_COMM_WORLD,PETSC_TRUE,0,0,&nullspace);
    1023:     MatNullSpaceRemove(nullspace,b);
    1024:     MatNullSpaceDestroy(&nullspace);
    1025:   }
    1026:   return 0;
    1027: }

    1029: PetscErrorCode ComputeRho(PetscInt i, PetscInt j, PetscInt mx, PetscInt my, PetscReal centerRho, PetscReal *rho)
    1030: {
    1032:   if ((i > mx/3.0) && (i < 2.0*mx/3.0) && (j > my/3.0) && (j < 2.0*my/3.0)) {
    1033:     *rho = centerRho;
    1034:   } else {
    1035:     *rho = 1.0;
    1036:   }
    1037:   return 0;
    1038: }

    1040: PetscErrorCode ComputeMatrix_DMDA(DM da,Mat J,Mat jac,void *ctx)
    1041: {
    1042:   UserContext    *user = (UserContext*)ctx;
    1043:   PetscReal      centerRho;
    1044:   PetscInt       i,j,mx,my,xm,ym,xs,ys;
    1045:   PetscScalar    v[5];
    1046:   PetscReal      Hx,Hy,HydHx,HxdHy,rho;
    1047:   MatStencil     row, col[5];
    1048:   PetscBool      isda = PETSC_FALSE;

    1051:   PetscObjectTypeCompare((PetscObject)da,DMDA,&isda);
    1053:   MatZeroEntries(jac);
    1054:   centerRho = user->rho;
    1055:   DMDAGetInfo(da,NULL,&mx,&my,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL);
    1056:   Hx        = 1.0 / (PetscReal)(mx-1);
    1057:   Hy        = 1.0 / (PetscReal)(my-1);
    1058:   HxdHy     = Hx/Hy;
    1059:   HydHx     = Hy/Hx;
    1060:   DMDAGetCorners(da,&xs,&ys,NULL,&xm,&ym,NULL);
    1061:   for (j=ys; j<ys+ym; j++) {
    1062:     for (i=xs; i<xs+xm; i++) {
    1063:       row.i = i; row.j = j;
    1064:       ComputeRho(i, j, mx, my, centerRho, &rho);
    1065:       if (i==0 || j==0 || i==mx-1 || j==my-1) {
    1066:         if (user->bcType == DIRICHLET) {
    1067:           v[0] = 2.0*rho*(HxdHy + HydHx);
    1068:           MatSetValuesStencil(jac,1,&row,1,&row,v,INSERT_VALUES);
    1069:         } else if (user->bcType == NEUMANN) {
    1070:           PetscInt numx = 0, numy = 0, num = 0;
    1071:           if (j!=0) {
    1072:             v[num] = -rho*HxdHy;  col[num].i = i;    col[num].j = j-1;
    1073:             numy++; num++;
    1074:           }
    1075:           if (i!=0) {
    1076:             v[num] = -rho*HydHx;  col[num].i = i-1;  col[num].j = j;
    1077:             numx++; num++;
    1078:           }
    1079:           if (i!=mx-1) {
    1080:             v[num] = -rho*HydHx;  col[num].i = i+1;  col[num].j = j;
    1081:             numx++; num++;
    1082:           }
    1083:           if (j!=my-1) {
    1084:             v[num] = -rho*HxdHy;  col[num].i = i;    col[num].j = j+1;
    1085:             numy++; num++;
    1086:           }
    1087:           v[num] = numx*rho*HydHx + numy*rho*HxdHy;  col[num].i = i; col[num].j = j;
    1088:           num++;
    1089:           MatSetValuesStencil(jac,1,&row,num,col,v,INSERT_VALUES);
    1090:         }
    1091:       } else {
    1092:         v[0] = -rho*HxdHy;              col[0].i = i;   col[0].j = j-1;
    1093:         v[1] = -rho*HydHx;              col[1].i = i-1; col[1].j = j;
    1094:         v[2] = 2.0*rho*(HxdHy + HydHx); col[2].i = i;   col[2].j = j;
    1095:         v[3] = -rho*HydHx;              col[3].i = i+1; col[3].j = j;
    1096:         v[4] = -rho*HxdHy;              col[4].i = i;   col[4].j = j+1;
    1097:         MatSetValuesStencil(jac,1,&row,5,col,v,INSERT_VALUES);
    1098:       }
    1099:     }
    1100:   }
    1101:   MatAssemblyBegin(jac,MAT_FINAL_ASSEMBLY);
    1102:   MatAssemblyEnd(jac,MAT_FINAL_ASSEMBLY);
    1103:   return 0;
    1104: }

    1106: PetscErrorCode ComputeMatrix_ShellDA(KSP ksp,Mat J,Mat jac,void *ctx)
    1107: {
    1108:   DM             dm,da;
    1110:   KSPGetDM(ksp,&dm);
    1111:   DMShellGetContext(dm,&da);
    1112:   ComputeMatrix_DMDA(da,J,jac,ctx);
    1113:   return 0;
    1114: }

    1116: /*TEST

    1118:   test:
    1119:     suffix: basic_dirichlet
    1120:     nsize: 4
    1121:     args: -tid 0 -ksp_monitor_short -pc_type telescope -telescope_ksp_max_it 100000 -telescope_pc_type lu -telescope_ksp_type fgmres -telescope_ksp_monitor_short -ksp_type gcr

    1123:   test:
    1124:     suffix: basic_neumann
    1125:     nsize: 4
    1126:     requires: !single
    1127:     args: -tid 0 -ksp_monitor_short -pc_type telescope -telescope_ksp_max_it 100000 -telescope_pc_type jacobi -telescope_ksp_type fgmres -telescope_ksp_monitor_short -ksp_type gcr -bc_type neumann

    1129:   test:
    1130:     suffix: mg_2lv_2mg
    1131:     nsize: 6
    1132:     args: -tid 2 -ksp_monitor_short -ksp_type gcr -pc_type mg -pc_mg_levels 3 -level_nrefs 3 -ndecomps 2 -mg_coarse_pc_type telescope -mg_coarse_pc_telescope_use_coarse_dm -mg_coarse_telescope_pc_type mg -mg_coarse_telescope_pc_mg_levels 3 -level_comm_red_factor 6 -mg_coarse_telescope_mg_coarse_pc_type lu

    1134:   test:
    1135:     suffix: mg_3lv_2mg
    1136:     nsize: 4
    1137:     args: -tid 2 -ksp_monitor_short -ksp_type gcr -pc_type mg -pc_mg_levels 3 -level_nrefs 3 -ndecomps 3 -mg_coarse_pc_type telescope -mg_coarse_pc_telescope_use_coarse_dm -mg_coarse_telescope_pc_type mg -mg_coarse_telescope_pc_mg_levels 3 -mg_coarse_telescope_mg_coarse_pc_type telescope -mg_coarse_telescope_mg_coarse_pc_telescope_use_coarse_dm -mg_coarse_telescope_mg_coarse_telescope_pc_type lu -m 5

    1139:   test:
    1140:     suffix: mg_3lv_2mg_customcommsize
    1141:     nsize: 12
    1142:     args: -tid 2 -ksp_monitor_short -ksp_type gcr -pc_type mg -pc_mg_levels 3 -level_nrefs 3 -ndecomps 3 -mg_coarse_pc_type telescope -mg_coarse_pc_telescope_use_coarse_dm  -m 5 -level_comm_red_factor 2,6 -mg_coarse_telescope_pc_type mg -mg_coarse_telescope_pc_mg_levels 3 -mg_coarse_telescope_mg_coarse_pc_type telescope -mg_coarse_telescope_mg_coarse_pc_telescope_use_coarse_dm -mg_coarse_telescope_mg_coarse_telescope_pc_type lu

    1144:  TEST*/