#include "petscmat.h" PetscErrorCode PETSCMAT_DLLEXPORT MatSeqAIJSetPreallocation(Mat B,PetscInt nz,const PetscInt nnz[])Collective on MPI_Comm
B | - The matrix | |
nz | - number of nonzeros per row (same for all rows) | |
nnz | - array containing the number of nonzeros in the various rows (possibly different for each row) or PETSC_NULL |
MatSeqAIJSetPreallocation(Mat A,const PetscInt nnz[]) | -> | MatSeqAIJSetPreallocation(A,0,nnz) |
The AIJ format (also called the Yale sparse matrix format or compressed row storage), is fully compatible with standard Fortran 77 storage. That is, the stored row and column indices can begin at either one (as in Fortran) or zero. See the users' manual for details.
Specify the preallocated storage with either nz or nnz (not both). Set nz=PETSC_DEFAULT and nnz=PETSC_NULL for PETSc to control dynamic memory allocation. For large problems you MUST preallocate memory or you will get TERRIBLE performance, see the users' manual chapter on matrices.
Developers: Use nz of MAT_SKIP_ALLOCATION to not allocate any space for the matrix entries or columns indices
By default, this format uses inodes (identical nodes) when possible, to improve numerical efficiency of matrix-vector products and solves. We search for consecutive rows with the same nonzero structure, thereby reusing matrix information to achieve increased efficiency.
-mat_no_inode | - Do not use inodes | |
-mat_inode_limit <limit> | - Sets inode limit (max limit=5) | |
-mat_aij_oneindex | - Internally use indexing starting at 1 rather than 0. Note that when calling MatSetValues(), the user still MUST index entries starting at 0! |
Level:intermediate
Location:src/mat/impls/aij/seq/aij.c
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Index of all manual pages