MatZeroRows

 Zeros all entries (except possibly the main diagonal) of a set of rows of a matrix.

Synopsis

#include "petscmat.h" 
int MatZeroRows(Mat mat,IS is,PetscScalar *diag)
Collective on Mat

Input Parameters

mat - the matrix
is - index set of rows to remove
diag - pointer to value put in all diagonals of eliminated rows. Note that diag is not a pointer to an array, but merely a pointer to a single value.

Notes

For the AIJ and BAIJ matrix formats this removes the old nonzero structure, but does not release memory. For the dense and block diagonal formats this does not alter the nonzero structure.

If the option MatSetOption(mat,MAT_KEEP_ZEROED_ROWS) the nonzero structure of the matrix is not changed (even for AIJ and BAIJ matrices) the values are merely zeroed.

The user can set a value in the diagonal entry (or for the AIJ and row formats can optionally remove the main diagonal entry from the nonzero structure as well, by passing a null pointer (PETSC_NULL in C or PETSC_NULL_SCALAR in Fortran) as the final argument).

For the parallel case, all processes that share the matrix (i.e., those in the communicator used for matrix creation) MUST call this routine, regardless of whether any rows being zeroed are owned by them.

For the SBAIJ matrix (since only the upper triangular half of the matrix is stored) the effect of this call is to also zero the corresponding column.

See Also

MatZeroEntries(), MatZeroRowsLocal(), MatSetOption()

Level:intermediate
Location:src/mat/interface/matrix.c
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages

Examples

src/sles/examples/tutorials/ex3.c.html