petsc-3.14.6 2021-03-30

DMGlobalToLocalSolve

Solve for the global vector that is mapped to a given local vector by DMGlobalToLocalBegin()/DMGlobalToLocalEnd() with mode = INSERT_VALUES. It is assumed that the sum of all the local vector sizes is greater than or equal to the global vector size, so the solution is a least-squares solution. It is also assumed that DMLocalToGlobalBegin()/DMLocalToGlobalEnd() with mode = ADD_VALUES is the adjoint of the global-to-local map, so that the least-squares solution may be found by the normal equations.

Synopsis

#include "petscdm.h" 
#include "petscdmplex.h" 
#include "petscksp.h" 
PetscErrorCode DMGlobalToLocalSolve(DM dm, Vec x, Vec y)

collective

Input Parameters

	dm	- The DM object
	x	- The local vector
	y	- The global vector: the input value of globalVec is used as an initial guess

Output Parameters

- The least-squares solution

Note: If the DM is of type DMPLEX, then y is the solution of L' * D * L * y = L' * D * x, where D is a diagonal mask that is 1 for every point in the union of the closures of the local cells and 0 otherwise. This difference is only relevant if there are anchor points that are not in the closure of any local cell (see DMPlexGetAnchors()/DMPlexSetAnchors()).

Level

advanced

Location