Date: 2022-03-31T04:47:23+00:00

Actual source code: sorder.c

      2: /*
      3:      Provides the code that allows PETSc users to register their own
      4:   sequential matrix Ordering routines.
      5: */
      6: #include <petsc/private/matimpl.h>
      7: #include <petscmat.h>

      9: PetscFunctionList MatOrderingList              = NULL;
     10: PetscBool         MatOrderingRegisterAllCalled = PETSC_FALSE;

     12: extern PetscErrorCode MatGetOrdering_Flow_SeqAIJ(Mat,MatOrderingType,IS*,IS*);

     14: PetscErrorCode MatGetOrdering_Flow(Mat mat,MatOrderingType type,IS *irow,IS *icol)
     15: {
     16:   SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_SUP,"Cannot do default flow ordering for matrix type");
     17: }

     19: PETSC_INTERN PetscErrorCode MatGetOrdering_Natural(Mat mat,MatOrderingType type,IS *irow,IS *icol)
     20: {
     21:   PetscInt       n,i,*ii;
     22:   PetscBool      done;
     23:   MPI_Comm       comm;

     25:   PetscObjectGetComm((PetscObject)mat,&comm);
     26:   MatGetRowIJ(mat,0,PETSC_FALSE,PETSC_TRUE,&n,NULL,NULL,&done);
     27:   MatRestoreRowIJ(mat,0,PETSC_FALSE,PETSC_TRUE,NULL,NULL,NULL,&done);
     28:   if (done) { /* matrix may be "compressed" in symbolic factorization, due to i-nodes or block storage */
     29:     /*
     30:       We actually create general index sets because this avoids mallocs to
     31:       to obtain the indices in the MatSolve() routines.
     32:       ISCreateStride(PETSC_COMM_SELF,n,0,1,irow);
     33:       ISCreateStride(PETSC_COMM_SELF,n,0,1,icol);
     34:     */
     35:     PetscMalloc1(n,&ii);
     36:     for (i=0; i<n; i++) ii[i] = i;
     37:     ISCreateGeneral(PETSC_COMM_SELF,n,ii,PETSC_COPY_VALUES,irow);
     38:     ISCreateGeneral(PETSC_COMM_SELF,n,ii,PETSC_OWN_POINTER,icol);
     39:   } else {
     40:     PetscInt start,end;

     42:     MatGetOwnershipRange(mat,&start,&end);
     43:     ISCreateStride(comm,end-start,start,1,irow);
     44:     ISCreateStride(comm,end-start,start,1,icol);
     45:   }
     46:   ISSetIdentity(*irow);
     47:   ISSetIdentity(*icol);
     48:   return 0;
     49: }

     51: /*
     52:      Orders the rows (and columns) by the lengths of the rows.
     53:    This produces a symmetric Ordering but does not require a
     54:    matrix with symmetric non-zero structure.
     55: */
     56: PETSC_INTERN PetscErrorCode MatGetOrdering_RowLength(Mat mat,MatOrderingType type,IS *irow,IS *icol)
     57: {
     58:   PetscInt       n,*permr,*lens,i;
     59:   const PetscInt *ia,*ja;
     60:   PetscBool      done;

     62:   MatGetRowIJ(mat,0,PETSC_FALSE,PETSC_TRUE,&n,&ia,&ja,&done);

     65:   PetscMalloc2(n,&lens,n,&permr);
     66:   for (i=0; i<n; i++) {
     67:     lens[i]  = ia[i+1] - ia[i];
     68:     permr[i] = i;
     69:   }
     70:   MatRestoreRowIJ(mat,0,PETSC_FALSE,PETSC_TRUE,NULL,&ia,&ja,&done);

     72:   PetscSortIntWithPermutation(n,lens,permr);

     74:   ISCreateGeneral(PETSC_COMM_SELF,n,permr,PETSC_COPY_VALUES,irow);
     75:   ISCreateGeneral(PETSC_COMM_SELF,n,permr,PETSC_COPY_VALUES,icol);
     76:   PetscFree2(lens,permr);
     77:   return 0;
     78: }

     80: /*@C
     81:    MatOrderingRegister - Adds a new sparse matrix ordering to the matrix package.

     83:    Not Collective

     85:    Input Parameters:
     86: +  sname - name of ordering (for example MATORDERINGND)
     87: -  function - function pointer that creates the ordering

     89:    Level: developer

     91:    Sample usage:
     92: .vb
     93:    MatOrderingRegister("my_order", MyOrder);
     94: .ve

     96:    Then, your partitioner can be chosen with the procedural interface via
     97: $     MatOrderingSetType(part,"my_order)
     98:    or at runtime via the option
     99: $     -pc_factor_mat_ordering_type my_order

    101: .seealso: MatOrderingRegisterAll()
    102: @*/
    103: PetscErrorCode  MatOrderingRegister(const char sname[],PetscErrorCode (*function)(Mat,MatOrderingType,IS*,IS*))
    104: {
    105:   MatInitializePackage();
    106:   PetscFunctionListAdd(&MatOrderingList,sname,function);
    107:   return 0;
    108: }

    110: #include <../src/mat/impls/aij/mpi/mpiaij.h>
    111: /*@C
    112:    MatGetOrdering - Gets a reordering for a matrix to reduce fill or to
    113:    improve numerical stability of LU factorization.

    115:    Collective on Mat

    117:    Input Parameters:
    118: +  mat - the matrix
    119: -  type - type of reordering, one of the following:
    120: $      MATORDERINGNATURAL_OR_ND - Nested dissection unless matrix is SBAIJ then it is natural
    121: $      MATORDERINGNATURAL - Natural
    122: $      MATORDERINGND - Nested Dissection
    123: $      MATORDERING1WD - One-way Dissection
    124: $      MATORDERINGRCM - Reverse Cuthill-McKee
    125: $      MATORDERINGQMD - Quotient Minimum Degree
    126: $      MATORDERINGEXTERNAL - Use an ordering internal to the factorzation package and do not compute or use PETSc's

    128:    Output Parameters:
    129: +  rperm - row permutation indices
    130: -  cperm - column permutation indices

    132:    Options Database Key:
    133: + -mat_view_ordering draw - plots matrix nonzero structure in new ordering
    134: - -pc_factor_mat_ordering_type <nd,natural,..> - ordering to use with PCs based on factorization, LU, ILU, Cholesky, ICC

    136:    Level: intermediate

    138:    Notes:
    139:       This DOES NOT actually reorder the matrix; it merely returns two index sets
    140:    that define a reordering. This is usually not used directly, rather use the
    141:    options PCFactorSetMatOrderingType()

    143:    The user can define additional orderings; see MatOrderingRegister().

    145:    These are generally only implemented for sequential sparse matrices.

    147:    Some external packages that PETSc can use for direct factorization such as SuperLU do not accept orderings provided by
    148:    this call.

    150:    If MATORDERINGEXTERNAL is used then PETSc does not compute an ordering and utilizes one built into the factorization package

    152:            fill, reordering, natural, Nested Dissection,
    153:            One-way Dissection, Cholesky, Reverse Cuthill-McKee,
    154:            Quotient Minimum Degree

    156: .seealso:   MatOrderingRegister(), PCFactorSetMatOrderingType(), MatColoring, MatColoringCreate()
    157: @*/
    158: PetscErrorCode  MatGetOrdering(Mat mat,MatOrderingType type,IS *rperm,IS *cperm)
    159: {
    160:   PetscInt       mmat,nmat,mis;
    161:   PetscErrorCode (*r)(Mat,MatOrderingType,IS*,IS*);
    162:   PetscBool      flg,ismpiaij;

    171:   PetscStrcmp(type,MATORDERINGEXTERNAL,&flg);
    172:   if (flg) {
    173:     *rperm = NULL;
    174:     *cperm = NULL;
    175:     return 0;
    176:   }

    178:   /* This code is terrible. MatGetOrdering() multiple dispatch should use matrix and this code should move to impls/aij/mpi. */
    179:   PetscObjectTypeCompare((PetscObject)mat,MATMPIAIJ,&ismpiaij);
    180:   if (ismpiaij) {               /* Reorder using diagonal block */
    181:     Mat            Ad,Ao;
    182:     const PetscInt *colmap;
    183:     IS             lrowperm,lcolperm;
    184:     PetscInt       i,rstart,rend,*idx;
    185:     const PetscInt *lidx;

    187:     MatMPIAIJGetSeqAIJ(mat,&Ad,&Ao,&colmap);
    188:     MatGetOrdering(Ad,type,&lrowperm,&lcolperm);
    189:     MatGetOwnershipRange(mat,&rstart,&rend);
    190:     /* Remap row index set to global space */
    191:     ISGetIndices(lrowperm,&lidx);
    192:     PetscMalloc1(rend-rstart,&idx);
    193:     for (i=0; i+rstart<rend; i++) idx[i] = rstart + lidx[i];
    194:     ISRestoreIndices(lrowperm,&lidx);
    195:     ISDestroy(&lrowperm);
    196:     ISCreateGeneral(PetscObjectComm((PetscObject)mat),rend-rstart,idx,PETSC_OWN_POINTER,rperm);
    197:     ISSetPermutation(*rperm);
    198:     /* Remap column index set to global space */
    199:     ISGetIndices(lcolperm,&lidx);
    200:     PetscMalloc1(rend-rstart,&idx);
    201:     for (i=0; i+rstart<rend; i++) idx[i] = rstart + lidx[i];
    202:     ISRestoreIndices(lcolperm,&lidx);
    203:     ISDestroy(&lcolperm);
    204:     ISCreateGeneral(PetscObjectComm((PetscObject)mat),rend-rstart,idx,PETSC_OWN_POINTER,cperm);
    205:     ISSetPermutation(*cperm);
    206:     return 0;
    207:   }

    209:   if (!mat->rmap->N) { /* matrix has zero rows */
    210:     ISCreateStride(PETSC_COMM_SELF,0,0,1,cperm);
    211:     ISCreateStride(PETSC_COMM_SELF,0,0,1,rperm);
    212:     ISSetIdentity(*cperm);
    213:     ISSetIdentity(*rperm);
    214:     return 0;
    215:   }

    217:   MatGetLocalSize(mat,&mmat,&nmat);

    220:   MatOrderingRegisterAll();
    221:   PetscFunctionListFind(MatOrderingList,type,&r);

    224:   PetscLogEventBegin(MAT_GetOrdering,mat,0,0,0);
    225:   (*r)(mat,type,rperm,cperm);
    226:   ISSetPermutation(*rperm);
    227:   ISSetPermutation(*cperm);
    228:   /* Adjust for inode (reduced matrix ordering) only if row permutation is smaller the matrix size */
    229:   ISGetLocalSize(*rperm,&mis);
    230:   if (mmat > mis) MatInodeAdjustForInodes(mat,rperm,cperm);
    231:   PetscLogEventEnd(MAT_GetOrdering,mat,0,0,0);

    233:   PetscOptionsHasName(((PetscObject)mat)->options,((PetscObject)mat)->prefix,"-mat_view_ordering",&flg);
    234:   if (flg) {
    235:     Mat tmat;
    236:     MatPermute(mat,*rperm,*cperm,&tmat);
    237:     MatViewFromOptions(tmat,(PetscObject)mat,"-mat_view_ordering");
    238:     MatDestroy(&tmat);
    239:   }
    240:   return 0;
    241: }

    243: PetscErrorCode MatGetOrderingList(PetscFunctionList *list)
    244: {
    245:   *list = MatOrderingList;
    246:   return 0;
    247: }