petsc-3.12.5 2020-03-29

DMLocalToGlobal

updates global vectors from local vectors

Synopsis

#include "petscdm.h"          
#include "petscdmlabel.h"     
#include "petscds.h"     
PetscErrorCode DMLocalToGlobal(DM dm,Vec l,InsertMode mode,Vec g)

Neighbor-wise Collective on dm

Input Parameters

	dm	- the DM object
	l	- the local vector
	mode	- if INSERT_VALUES then no parallel communication is used, if ADD_VALUES then all ghost points from the same base point accumulate into that base point.
	g	- the global vector

Notes

The communication involved in this update can be overlapped with computation by using DMLocalToGlobalBegin() and DMLocalToGlobalEnd().

In the ADD_VALUES case you normally would zero the receiving vector before beginning this operation. INSERT_VALUES is not supported for DMDA; in that case simply compute the values directly into a global vector instead of a local one.

Level

beginner

Location