MatShift#

Computes Y =  Y + a I, where a is a PetscScalar

Synopsis#

#include "petscmat.h"  
PetscErrorCode MatShift(Mat Y, PetscScalar a)

Neighbor-wise Collective

Input Parameters#

Notes#

If Y is a rectangular matrix, the shift is done on the main diagonal of the matrix (https://en.wikipedia.org/wiki/Main_diagonal)

If the matrix Y is missing some diagonal entries this routine can be very slow. To make it fast one should initially fill the matrix so that all diagonal entries have a value (with a value of zero for those locations that would not have an entry). No operation is performed when a is zero.

To form Y = Y + diag(V) use MatDiagonalSet()

See Also#

Matrices, Mat, MatDiagonalSet(), MatScale(), MatDiagonalScale()

Level#

intermediate

Location#

src/mat/utils/axpy.c

Examples#

src/ksp/ksp/tutorials/ex79.c
src/ksp/ksp/tutorials/ex1.c
src/tao/pde_constrained/tutorials/hyperbolic.c
src/tao/constrained/tutorials/tomographyADMM.c
src/ksp/ksp/tutorials/ex27.c
src/ksp/ksp/tutorials/ex81.c
src/tao/tutorials/ex4.c
src/ts/tutorials/ex16fwd.c
src/tao/pde_constrained/tutorials/parabolic.c
src/ksp/ksp/tutorials/ex82.c

Implementations#

MatShift_MPIAIJ() in src/mat/impls/aij/mpi/mpiaij.c
MatShift_SeqAIJ() in src/mat/impls/aij/seq/aij.c
MatShift_MPIBAIJ() in src/mat/impls/baij/mpi/mpibaij.c
MatShift_SeqBAIJ() in src/mat/impls/baij/seq/baij.c
MatShift_ConstantDiagonal() in src/mat/impls/cdiagonal/cdiagonal.c
MatShift_MPIDense() in src/mat/impls/dense/mpi/mpidense.c
MatShift_SeqDense() in src/mat/impls/dense/seq/dense.c
MatShift_Diagonal() in src/mat/impls/diagonal/diagonal.c
MatShift_IS() in src/mat/impls/is/matis.c
MatShift_Nest() in src/mat/impls/nest/matnest.c
MatShift_MPISBAIJ() in src/mat/impls/sbaij/mpi/mpisbaij.c
MatShift_SeqSBAIJ() in src/mat/impls/sbaij/seq/sbaij.c
MatShift_ScaLAPACK() in src/mat/impls/scalapack/matscalapack.c
MatShift_MPISELL() in src/mat/impls/sell/mpi/mpisell.c
MatShift_SeqSELL() in src/mat/impls/sell/seq/sell.c
MatShift_Shell() in src/mat/impls/shell/shell.c
MatShift_SubMatrix() in src/mat/impls/submat/submat.c

Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages