Actual source code: mpiaijsell.c

petsc-master 2019-06-22
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  1:  #include <../src/mat/impls/aij/mpi/mpiaij.h>
  2: /*@C
  3:    MatCreateMPIAIJSELL - Creates a sparse parallel matrix whose local
  4:    portions are stored as SEQAIJSELL matrices (a matrix class that inherits
  5:    from SEQAIJ but performs some operations in SELL format).  The same 
  6:    guidelines that apply to MPIAIJ matrices for preallocating the matrix 
  7:    storage apply here as well.

  9:       Collective

 11:    Input Parameters:
 12: +  comm - MPI communicator
 13: .  m - number of local rows (or PETSC_DECIDE to have calculated if M is given)
 14:            This value should be the same as the local size used in creating the
 15:            y vector for the matrix-vector product y = Ax.
 16: .  n - This value should be the same as the local size used in creating the
 17:        x vector for the matrix-vector product y = Ax. (or PETSC_DECIDE to have
 18:        calculated if N is given) For square matrices n is almost always m.
 19: .  M - number of global rows (or PETSC_DETERMINE to have calculated if m is given)
 20: .  N - number of global columns (or PETSC_DETERMINE to have calculated if n is given)
 21: .  d_nz  - number of nonzeros per row in DIAGONAL portion of local submatrix
 22:            (same value is used for all local rows)
 23: .  d_nnz - array containing the number of nonzeros in the various rows of the
 24:            DIAGONAL portion of the local submatrix (possibly different for each row)
 25:            or NULL, if d_nz is used to specify the nonzero structure.
 26:            The size of this array is equal to the number of local rows, i.e 'm'.
 27:            For matrices you plan to factor you must leave room for the diagonal entry and
 28:            put in the entry even if it is zero.
 29: .  o_nz  - number of nonzeros per row in the OFF-DIAGONAL portion of local
 30:            submatrix (same value is used for all local rows).
 31: -  o_nnz - array containing the number of nonzeros in the various rows of the
 32:            OFF-DIAGONAL portion of the local submatrix (possibly different for
 33:            each row) or NULL, if o_nz is used to specify the nonzero
 34:            structure. The size of this array is equal to the number
 35:            of local rows, i.e 'm'.

 37:    Output Parameter:
 38: .  A - the matrix

 40:    Notes:
 41:    If the *_nnz parameter is given then the *_nz parameter is ignored

 43:    m,n,M,N parameters specify the size of the matrix, and its partitioning across
 44:    processors, while d_nz,d_nnz,o_nz,o_nnz parameters specify the approximate
 45:    storage requirements for this matrix.

 47:    If PETSC_DECIDE or PETSC_DETERMINE is used for a particular argument on one
 48:    processor than it must be used on all processors that share the object for
 49:    that argument.

 51:    The user MUST specify either the local or global matrix dimensions
 52:    (possibly both).

 54:    The parallel matrix is partitioned such that the first m0 rows belong to
 55:    process 0, the next m1 rows belong to process 1, the next m2 rows belong
 56:    to process 2 etc.. where m0,m1,m2... are the input parameter 'm'.

 58:    The DIAGONAL portion of the local submatrix of a processor can be defined
 59:    as the submatrix which is obtained by extraction the part corresponding
 60:    to the rows r1-r2 and columns r1-r2 of the global matrix, where r1 is the
 61:    first row that belongs to the processor, and r2 is the last row belonging
 62:    to the this processor. This is a square mxm matrix. The remaining portion
 63:    of the local submatrix (mxN) constitute the OFF-DIAGONAL portion.

 65:    If o_nnz, d_nnz are specified, then o_nz, and d_nz are ignored.

 67:    When calling this routine with a single process communicator, a matrix of
 68:    type SEQAIJSELL is returned.  If a matrix of type MPIAIJSELL is desired
 69:    for this type of communicator, use the construction mechanism:
 70:      MatCreate(...,&A); MatSetType(A,MPIAIJSELL); MatMPIAIJSetPreallocation(A,...);

 72:    Options Database Keys:
 73: .  -mat_aijsell_eager_shadow - Construct shadow matrix upon matrix assembly; default is to take a "lazy" approach, performing this step the first time the matrix is applied

 75:    Level: intermediate

 77: .seealso: MatCreate(), MatCreateSeqAIJSELL(), MatSetValues()
 78: @*/
 79: PetscErrorCode  MatCreateMPIAIJSELL(MPI_Comm comm,PetscInt m,PetscInt n,PetscInt M,PetscInt N,PetscInt d_nz,const PetscInt d_nnz[],PetscInt o_nz,const PetscInt o_nnz[],Mat *A)
 80: {
 82:   PetscMPIInt    size;

 85:   MatCreate(comm,A);
 86:   MatSetSizes(*A,m,n,M,N);
 87:   MPI_Comm_size(comm,&size);
 88:   if (size > 1) {
 89:     MatSetType(*A,MATMPIAIJSELL);
 90:     MatMPIAIJSetPreallocation(*A,d_nz,d_nnz,o_nz,o_nnz);
 91:   } else {
 92:     MatSetType(*A,MATSEQAIJSELL);
 93:     MatSeqAIJSetPreallocation(*A,d_nz,d_nnz);
 94:   }
 95:   return(0);
 96: }

 98: PETSC_INTERN PetscErrorCode MatConvert_SeqAIJ_SeqAIJSELL(Mat,MatType,MatReuse,Mat*);

100: PetscErrorCode  MatMPIAIJSetPreallocation_MPIAIJSELL(Mat B,PetscInt d_nz,const PetscInt d_nnz[],PetscInt o_nz,const PetscInt o_nnz[])
101: {
102:   Mat_MPIAIJ     *b = (Mat_MPIAIJ*)B->data;

106:   MatMPIAIJSetPreallocation_MPIAIJ(B,d_nz,d_nnz,o_nz,o_nnz);
107:   MatConvert_SeqAIJ_SeqAIJSELL(b->A, MATSEQAIJSELL, MAT_INPLACE_MATRIX, &b->A);
108:   MatConvert_SeqAIJ_SeqAIJSELL(b->B, MATSEQAIJSELL, MAT_INPLACE_MATRIX, &b->B);
109:   return(0);
110: }

112: PETSC_INTERN PetscErrorCode MatConvert_MPIAIJ_MPIAIJSELL(Mat A,MatType type,MatReuse reuse,Mat *newmat)
113: {
115:   Mat            B = *newmat;

118:   if (reuse == MAT_INITIAL_MATRIX) {
119:     MatDuplicate(A,MAT_COPY_VALUES,&B);
120:   }

122:   PetscObjectChangeTypeName((PetscObject) B, MATMPIAIJSELL);
123:   PetscObjectComposeFunction((PetscObject)B,"MatMPIAIJSetPreallocation_C",MatMPIAIJSetPreallocation_MPIAIJSELL);
124:   *newmat = B;
125:   return(0);
126: }

128: PETSC_EXTERN PetscErrorCode MatCreate_MPIAIJSELL(Mat A)
129: {

133:   MatSetType(A,MATMPIAIJ);
134:   MatConvert_MPIAIJ_MPIAIJSELL(A,MATMPIAIJSELL,MAT_INPLACE_MATRIX,&A);
135:   return(0);
136: }

138: /*MC
139:    MATAIJSELL - MATAIJSELL = "AIJSELL" - A matrix type to be used for sparse matrices.

141:    This matrix type is identical to MATSEQAIJSELL when constructed with a single process communicator,
142:    and MATMPIAIJSELL otherwise.  As a result, for single process communicators,
143:    MatSeqAIJSetPreallocation() is supported, and similarly MatMPIAIJSetPreallocation() is supported
144:    for communicators controlling multiple processes.  It is recommended that you call both of
145:    the above preallocation routines for simplicity.

147:    Options Database Keys:
148: . -mat_type aijsell - sets the matrix type to "AIJSELL" during a call to MatSetFromOptions()

150:   Level: beginner

152: .seealso: MatCreateMPIAIJSELL(), MATSEQAIJSELL, MATMPIAIJSELL
153: M*/