DMGlobalToLocalSolve#
Solve for the global vector that is mapped to a given local vector by DMGlobalToLocalBegin()/DMGlobalToLocalEnd() with mode INSERT_VALUES.
Synopsis#
#include "petscdm.h"
#include "petscdmda.h"
#include "petscdmplex.h"
#include "petscdmswarm.h"
#include "petscksp.h"
PetscErrorCode DMGlobalToLocalSolve(DM dm, Vec x, Vec y)
Collective
Input Parameters#
dm - The
DMobjectx - The local vector
y - The global vector: the input value of globalVec is used as an initial guess
Output Parameter#
y - The least-squares solution
Note#
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.
If the DM is of type DMPLEX, then y is the solution of \( L^T * D * L * y = L^T * D * x \), 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()).
What is L?
If this solves for a global vector from a local vector why is not called DMLocalToGlobalSolve()?
See Also#
DM Basics, DM, DMGlobalToLocalBegin(), DMGlobalToLocalEnd(), DMLocalToGlobalBegin(), DMLocalToGlobalEnd(), DMPlexGetAnchors(), DMPlexSetAnchors()
Level#
advanced
Location#
src/ksp/ksp/utils/dm/dmproject.c
Index of all DM routines
Table of Contents for all manual pages
Index of all manual pages