MatCreateMPIAIJPERM#
Creates a sparse parallel matrix whose local portions are stored as MATSEQAIJPERM
matrices (a matrix class that inherits from SEQAIJ but includes some optimizations to allow more effective vectorization).
Synopsis#
Collective
Input Parameters#
comm - MPI communicator
m - number of local rows (or
PETSC_DECIDE
to have calculated ifM
is given) This value should be the same as the local size used in creating the y vector for the matrix-vector product y = Ax.n - This value should be the same as the local size used in creating the x vector for the matrix-vector product y = Ax. (or PETSC_DECIDE to have calculated if
N
is given) For square matricesn
is almost alwaysm
.M - number of global rows (or
PETSC_DETERMINE
to have calculated ifm
is given)N - number of global columns (or
PETSC_DETERMINE
to have calculated ifn
is given)d_nz - number of nonzeros per row in DIAGONAL portion of local submatrix (same value is used for all local rows)
d_nnz - array containing the number of nonzeros in the various rows of the DIAGONAL portion of the local submatrix (possibly different for each row) or
NULL
, ifd_nz
is used to specify the nonzero structure. The size of this array is equal to the number of local rows, i.em
. For matrices you plan to factor you must leave room for the diagonal entry and put in the entry even if it is zero.o_nz - number of nonzeros per row in the OFF-DIAGONAL portion of local submatrix (same value is used for all local rows).
o_nnz - array containing the number of nonzeros in the various rows of the OFF-DIAGONAL portion of the local submatrix (possibly different for each row) or
NULL
, ifo_nz
is used to specify the nonzero structure. The size of this array is equal to the number of local rows, i.em
.
Output Parameter#
A - the matrix
Options Database Keys#
-mat_no_inode - Do not use inodes
-mat_inode_limit
- Sets inode limit (max limit=5)
Notes#
If the *_nnz parameter is given then the *_nz parameter is ignored
m
,n
,M
,N
parameters specify the size of the matrix, and its partitioning across
processors, while d_nz
,d_nnz
,o_nz
,o_nnz
parameters specify the approximate
storage requirements for this matrix.
If PETSC_DECIDE
or PETSC_DETERMINE
is used for a particular argument on one
processor than it must be used on all processors that share the object for
that argument.
The user MUST specify either the local or global matrix dimensions (possibly both).
The parallel matrix is partitioned such that the first m0 rows belong to
process 0, the next m1 rows belong to process 1, the next m2 rows belong
to process 2 etc.. where m0,m1,m2… are the input parameter m
.
The DIAGONAL portion of the local submatrix of a processor can be defined as the submatrix which is obtained by extraction the part corresponding to the rows r1-r2 and columns r1-r2 of the global matrix, where r1 is the first row that belongs to the processor, and r2 is the last row belonging to the this processor. This is a square mxm matrix. The remaining portion of the local submatrix (mxN) constitute the OFF-DIAGONAL portion.
If o_nnz
, d_nnz
are specified, then o_nz
, and d_nz
are ignored.
When calling this routine with a single process communicator, a matrix of
type MATSEQAIJPERM
is returned. If a matrix of type MATMPIAIJPERM
is desired
for this type of communicator, use the construction mechanism
MatCreate(...,&A);
MatSetType(A,MPIAIJ);
MatMPIAIJSetPreallocation(A,...);
By default, this format uses inodes (identical nodes) when possible. We search for consecutive rows with the same nonzero structure, thereby reusing matrix information to achieve increased efficiency.
See Also#
Matrices, Mat
, Sparse Matrix Creation, MATMPIAIJPERM
, MatCreate()
, MatCreateSeqAIJPERM()
, MatSetValues()
Level#
intermediate
Location#
src/mat/impls/aij/mpi/aijperm/mpiaijperm.c
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