MatZeroRowsColumnsStencil#
Zeros all row and column entries (except possibly the main diagonal) of a set of rows and columns of a matrix.
Synopsis#
#include "petscmat.h"
PetscErrorCode MatZeroRowsColumnsStencil(Mat mat, PetscInt numRows, const MatStencil rows[], PetscScalar diag, Vec x, Vec b)
Collective
Input Parameters#
mat - the matrix
numRows - the number of rows/columns to remove
rows - the grid coordinates (and component number when dof > 1) for matrix rows
diag - value put in all diagonals of eliminated rows (0.0 will even eliminate diagonal entry)
x - optional vector of solutions for zeroed rows (other entries in vector are not used)
b - optional vector of right-hand side, that will be adjusted by provided solution
Notes#
See MatZeroRowsColumns() for details on how this routine operates.
The grid coordinates are across the entire grid, not just the local portion
For periodic boundary conditions use negative indices for values to the left (below 0; that are to be
obtained by wrapping values from right edge). For values to the right of the last entry using that index plus one
etc to obtain values that obtained by wrapping the values from the left edge. This does not work for anything but the
DM_BOUNDARY_PERIODIC boundary type.
For indices that don’t mean anything for your case (like the k index when working in 2d) or the c index when you have a single value per point) you can skip filling those indices.
Fortran Note#
idxm and idxn should be declared as
MatStencil idxm(4, m)
and the values inserted using
idxm(MatStencil_i, 1) = i
idxm(MatStencil_j, 1) = j
idxm(MatStencil_k, 1) = k
idxm(MatStencil_c, 1) = c
etc
See Also#
Matrices, Mat, MatZeroRowsIS(), MatZeroRowsColumns(), MatZeroRowsLocalIS(), MatZeroRowsStencil(), MatZeroEntries(), MatZeroRowsLocal(), MatSetOption(),
MatZeroRowsColumnsLocal(), MatZeroRowsColumnsLocalIS(), MatZeroRowsColumnsIS(), MatZeroRows()
Level#
intermediate
Location#
Examples#
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages