VecScatterBegin#

Begins a generalized scatter from one vector to another. Complete the scattering phase with VecScatterEnd().

Synopsis#

#include "petscsf.h" 
PetscErrorCode VecScatterBegin(VecScatter sf, Vec x, Vec y, InsertMode addv, ScatterMode mode)

Neighbor-wise Collective

Input Parameters#

Notes#

The vectors x and y need not be the same vectors used in the call to VecScatterCreate(), but x must have the same parallel data layout as that passed in as the x to VecScatterCreate(), similarly for the y. Most likely they have been obtained from VecDuplicate().

You cannot change the values in the input vector between the calls to VecScatterBegin() and VecScatterEnd().

If you use SCATTER_REVERSE the two arguments x and y should be reversed, from the SCATTER_FORWARD.

y[iy[i]] = x[ix[i]], for i=0,…,ni-1

This scatter is far more general than the conventional scatter, since it can be a gather or a scatter or a combination, depending on the indices ix and iy. If x is a parallel vector and y is sequential, VecScatterBegin() can serve to gather values to a single processor. Similarly, if y is parallel and x sequential, the routine can scatter from one processor to many processors.

See Also#

Low-level Vector Communication, VecScatter, VecScatterCreate(), VecScatterEnd()

Level#

intermediate

Location#

src/vec/is/sf/interface/vscat.c

Examples#

src/vec/vec/utils/tagger/tutorials/ex1.c.html
src/vec/vec/tutorials/ex44.c.html
src/dm/tutorials/ex14.c.html
src/dm/tutorials/ex22.c.html
src/dm/tutorials/ex25.c.html
src/dm/tutorials/ex6.c.html
src/ksp/ksp/tutorials/ex43.c.html
src/ksp/ksp/tutorials/ex49.c.html
src/ksp/ksp/tutorials/ex73.c.html
src/ts/tutorials/ex29.c.html
src/tao/constrained/tutorials/ex1.c.html


Edit on GitLab

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