# MatSetValues
Inserts or adds a block of values into a matrix. These values may be cached, so `MatAssemblyBegin()` and `MatAssemblyEnd()` MUST be called after all calls to `MatSetValues()` have been completed. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatSetValues(Mat mat, PetscInt m, const PetscInt idxm[], PetscInt n, const PetscInt idxn[], const PetscScalar v[], InsertMode addv)
```
Not Collective


## Input Parameters

- ***mat -*** the matrix
- ***v -*** a logically two-dimensional array of values
- ***m, idxm -*** the number of rows and their global indices
- ***n, idxn -*** the number of columns and their global indices
- ***addv -*** either `ADD_VALUES` to add values to any existing entries, or `INSERT_VALUES` to replace existing entries with new values



## Notes
If you create the matrix yourself (that is not with a call to `DMCreateMatrix()`) then you MUST call MatXXXXSetPreallocation() or
`MatSetUp()` before using this routine

By default the values, v, are row-oriented. See `MatSetOption()` for other options.

Calls to `MatSetValues()` with the `INSERT_VALUES` and `ADD_VALUES`
options cannot be mixed without intervening calls to the assembly
routines.

`MatSetValues()` uses 0-based row and column numbers in Fortran
as well as in C.

Negative indices may be passed in idxm and idxn, these rows and columns are
simply ignored. This allows easily inserting element stiffness matrices
with homogeneous Dirchlet boundary conditions that you don't want represented
in the matrix.


## Efficiency Alert
The routine `MatSetValuesBlocked()` may offer much better efficiency
for users of block sparse formats (`MATSEQBAIJ` and `MATMPIBAIJ`).




## Developer Note
This is labeled with C so does not automatically generate Fortran stubs and interfaces
because it requires multiple Fortran interfaces depending on which arguments are scalar or arrays.


## See Also
 `Mat`, `MatSetOption()`, `MatAssemblyBegin()`, `MatAssemblyEnd()`, `MatSetValuesBlocked()`, `MatSetValuesLocal()`,
`InsertMode`, `INSERT_VALUES`, `ADD_VALUES`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/interface/matrix.c.html#MatSetValues">src/mat/interface/matrix.c</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex12.c.html">src/mat/tutorials/ex12.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex15.c.html">src/mat/tutorials/ex15.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex15f.F90.html">src/mat/tutorials/ex15f.F90.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex16.c.html">src/mat/tutorials/ex16.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex17.c.html">src/mat/tutorials/ex17.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex17f.F90.html">src/mat/tutorials/ex17f.F90.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex18.c.html">src/mat/tutorials/ex18.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex2.c.html">src/mat/tutorials/ex2.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex3.c.html">src/mat/tutorials/ex3.c.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex5cu.cu.html">src/mat/tutorials/ex5cu.cu.html</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/tutorials/ex5k.kokkos.cxx.html">src/mat/tutorials/ex5k.kokkos.cxx.html</A><BR>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/adj/mpi/mpiadj.c.html#MatSetValues_MPIAdj">MatSetValues_MPIAdj in src/mat/impls/adj/mpi/mpiadj.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/mpi/mpiaij.c.html#MatSetValues_MPIAIJ">MatSetValues_MPIAIJ in src/mat/impls/aij/mpi/mpiaij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/aij.c.html#MatSetValues_SeqAIJ">MatSetValues_SeqAIJ in src/mat/impls/aij/seq/aij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/baij/mpi/mpibaij.c.html#MatSetValues_MPIBAIJ">MatSetValues_MPIBAIJ in src/mat/impls/baij/mpi/mpibaij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/baij/seq/baij.c.html#MatSetValues_SeqBAIJ">MatSetValues_SeqBAIJ in src/mat/impls/baij/seq/baij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/blockmat/seq/blockmat.c.html#MatSetValues_BlockMat">MatSetValues_BlockMat in src/mat/impls/blockmat/seq/blockmat.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/dense/mpi/mpidense.c.html#MatSetValues_MPIDense">MatSetValues_MPIDense in src/mat/impls/dense/mpi/mpidense.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/dense/seq/dense.c.html#MatSetValues_SeqDense">MatSetValues_SeqDense in src/mat/impls/dense/seq/dense.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/elemental/matelem.cxx.html#MatSetValues_Elemental">MatSetValues_Elemental in src/mat/impls/elemental/matelem.cxx</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/hypre/mhypre.c.html#MatSetValues_HYPRE">MatSetValues_HYPRE in src/mat/impls/hypre/mhypre.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/is/matis.c.html#MatSetValues_IS">MatSetValues_IS in src/mat/impls/is/matis.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/preallocator/matpreallocator.c.html#MatSetValues_Preallocator">MatSetValues_Preallocator in src/mat/impls/preallocator/matpreallocator.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sbaij/mpi/mpisbaij.c.html#MatSetValues_MPISBAIJ">MatSetValues_MPISBAIJ in src/mat/impls/sbaij/mpi/mpisbaij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sbaij/seq/sbaij.c.html#MatSetValues_SeqSBAIJ">MatSetValues_SeqSBAIJ in src/mat/impls/sbaij/seq/sbaij.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/scalapack/matscalapack.c.html#MatSetValues_ScaLAPACK">MatSetValues_ScaLAPACK in src/mat/impls/scalapack/matscalapack.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sell/mpi/mpisell.c.html#MatSetValues_MPISELL">MatSetValues_MPISELL in src/mat/impls/sell/mpi/mpisell.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/sell/seq/sell.c.html#MatSetValues_SeqSELL">MatSetValues_SeqSELL in src/mat/impls/sell/seq/sell.c</A><BR>


---
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