petsc-3.12.1 2019-10-22
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# MatCreateConstantDiagonal

Creates a matrix with a uniform value along the diagonal

### Synopsis

    #include "petscmat.h"
    PetscErrorCode  MatCreateConstantDiagonal(MPI_Comm comm,PetscInt m,PetscInt n,PetscInt M,PetscInt N,PetscScalar diag,Mat *J)

Collective

### Input Parameters

| comm | - MPI communicator
| m | - number of local rows (or PETSC_DECIDE to have calculated if M is given) This value should be the same as the local size used in creating the y vector for the matrix-vector product y = Ax.
| n | - This value should be the same as the local size used in creating the x vector for the matrix-vector product y = Ax. (or PETSC_DECIDE to have calculated if N is given) For square matrices n is almost always m.
| M | - number of global rows (or PETSC_DETERMINE to have calculated if m is given)
| N | - number of global columns (or PETSC_DETERMINE to have calculated if n is given)
| diag | - the diagonal value

### Output Parameter

J -the diagonal matrix

### Notes

Only supports square matrices with the same number of local rows and columns

### See Also

MatDestroy(), MATCONSTANTDIAGONAL, MatScale(), MatShift(), MatMult(), MatGetDiagonal(), MatGetFactor(), MatSolve()

### Level

advanced

### Location

src/mat/impls/cdiagonal/cdiagonal.c
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages