petsc-3.14.5 2021-03-03
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# MatCompositeSetMergeType

Sets order of MatCompositeMerge().

### Synopsis

    #include "petscmat.h"
    PetscErrorCode MatCompositeSetMergeType(Mat mat,MatCompositeMergeType type)

Logically Collective on Mat

### Input Parameter

| mat | - the composite matrix
| type | - MAT_COMPOSITE_MERGE RIGHT (default) to start merge from right with the first added matrix (mat[0]), MAT_COMPOSITE_MERGE_LEFT to start merge from left with the last added matrix (mat[nmat-1])

### Notes

The resulting matrix is the same regardles of the MergeType. Only the order of operation is changed. If set to MAT_COMPOSITE_MERGE_RIGHT the order of the merge is mat[nmat-1]*(mat[nmat-2]*(...*(mat[1]*mat[0]))) otherwise the order is (((mat[nmat-1]*mat[nmat-2])*mat[nmat-3])*...)*mat[0].

### See Also

MatCreateComposite(), MatCompositeMerge(), MATCOMPOSITE

### Level

advanced

### Location

src/mat/impls/composite/mcomposite.c

### Examples

src/mat/tutorials/ex9.c.html

### Implementations

MatCompositeSetMergeType_Composite in src/mat/impls/composite/mcomposite.c
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