petsc-3.14.5 2021-03-03
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# MatSeqSBAIJSetPreallocationCSR

Creates a sparse parallel matrix in SBAIJ format using the given nonzero structure and (optional) numerical values

### Synopsis

    #include "petscmat.h"
    PetscErrorCode MatSeqSBAIJSetPreallocationCSR(Mat B,PetscInt bs,const PetscInt i[],const PetscInt j[], const PetscScalar v[])

### Input Parameters

| B | - the matrix
| bs | - size of block, the blocks are ALWAYS square.
| i | - the indices into j for the start of each local row (starts with zero)
| j | - the column indices for each local row (starts with zero) these must be sorted for each row
| v | - optional values in the matrix

### Notes

The order of the entries in values is specified by the MatOption MAT_ROW_ORIENTED. For example, C programs may want to use the default MAT_ROW_ORIENTED=PETSC_TRUE and use an array v[nnz][bs][bs] where the second index is over rows within a block and the last index is over columns within a block row. Fortran programs will likely set MAT_ROW_ORIENTED=PETSC_FALSE and use a Fortran array v(bs,bs,nnz) in which the first index is over rows within a block column and the second index is over columns within a block.

Any entries below the diagonal are ignored

Though this routine has Preallocation() in the name it also sets the exact nonzero locations of the matrix entries and usually the numerical values as well

### See Also

MatCreate(), MatCreateSeqSBAIJ(), MatSetValuesBlocked(), MatSeqSBAIJSetPreallocation(), MATSEQSBAIJ

### Level

advanced

### Location

src/mat/impls/sbaij/seq/sbaij.c

### Implementations

MatSeqSBAIJSetPreallocationCSR_SeqSBAIJ in src/mat/impls/sbaij/seq/sbaij.c
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