MatCreateSeqAIJFromTriple — PETSc 3.21.4 documentation

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# MatCreateSeqAIJFromTriple

Creates an sequential `MATSEQAIJ` matrix using matrix elements (in COO format) provided by the user.

## Synopsis

    #include "petscmat.h"
    PetscErrorCode MatCreateSeqAIJFromTriple(MPI_Comm comm, PetscInt m, PetscInt n, PetscInt i[], PetscInt j[], PetscScalar a[], Mat *mat, PetscInt nz, PetscBool idx)

Collective

## Input Parameters

- comm - must be an MPI communicator of size 1

- m - number of rows

- n - number of columns

- i - row indices

- j - column indices

- a - matrix values

- nz - number of nonzeros

- idx - if the `i` and `j` indices start with 1 use `PETSC_TRUE` otherwise use `PETSC_FALSE`

## Output Parameter

- mat - the matrix

## Example

For the following matrix, the input data expected is as shown (using 0 based indexing)

            1 0 0
            2 0 3
            4 5 6

            i =  {0,1,1,2,2,2}
            j =  {0,0,2,0,1,2}
            v =  {1,2,3,4,5,6}

## Note

Instead of using this function, users should also consider `MatSetPreallocationCOO()` and `MatSetValuesCOO()`, which allow repeated or remote entries, and are particularly useful in iterative applications.

## See Also

Matrices, `Mat`, `MatCreate()`, `MatCreateAIJ()`, `MatCreateSeqAIJ()`, `MatCreateSeqAIJWithArrays()`, `MatMPIAIJSetPreallocationCSR()`, `MatSetValuesCOO()`, `MatSetPreallocationCOO()`

## Level

intermediate

## Location

src/mat/impls/aij/seq/aij.c

## Examples

src/ksp/ksp/tutorials/ex83f.F90

Index of all Mat routines
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Index of all manual pages