DMPlexSectionLoad#
Loads section into a DMPLEX
Synopsis#
#include "petscdmplex.h"   
PetscErrorCode DMPlexSectionLoad(DM dm, PetscViewer viewer, DM sectiondm, PetscSF globalToLocalPointSF, PetscSF *globalDofSF, PetscSF *localDofSF)
Collective
Input Parameters#
- dm - The - DMthat represents the topology
- viewer - The - PetscViewerthat represents the on-disk section (sectionA)
- sectiondm - The - DMinto which the on-disk section (sectionA) is migrated, can be- NULL
- globalToLocalPointSF - The - PetscSFreturned by- DMPlexTopologyLoad() when loading dm from viewer
Output Parameters#
- globalDofSF - The - PetscSFthat migrates any on-disk- Vecdata associated with sectionA into a global- Vecassociated with the- sectiondm’s global section (- NULLif not needed)
- localDofSF - The - PetscSFthat migrates any on-disk- Vecdata associated with sectionA into a local- Vecassociated with the- sectiondm’s local section (- NULLif not needed)
Notes#
This function is a wrapper around PetscSectionLoad(); it loads, in addition to the raw section, a list of global point numbers that associates each on-disk section point with a global point number in [0, NX), where NX is the number of topology points in dm. Noting that globalToLocalPointSF associates each topology point in dm with a global number in [0, NX), one can readily establish an association of the on-disk section points with the topology points.
In general dm and sectiondm are two different objects, the former carrying the topology and the latter carrying the section, and have been given a topology name and a section name, respectively, with PetscObjectSetName(). In practice, however, they can be the same object (or in case sectiondm is NULL) if it carries both topology and section; in that case the name of the object is used as both the topology name and the section name.
The output parameter, globalDofSF (localDofSF), can later be used with DMPlexGlobalVectorLoad() (DMPlexLocalVectorLoad()) to load on-disk vectors into global (local) vectors associated with sectiondm’s global (local) section.
Example using 2 processes#
  NX (number of points on dm): 4
  sectionA                   : the on-disk section
  vecA                       : a vector associated with sectionA
  sectionB                   : sectiondm's local section constructed in this function
  vecB (local)               : a vector associated with sectiondm's local section
  vecB (global)              : a vector associated with sectiondm's global section
                                     rank 0    rank 1
  vecA (global)                  : [.0 .4 .1 | .2 .3]        <- to be loaded in DMPlexGlobalVectorLoad() or DMPlexLocalVectorLoad()
  sectionA->atlasOff             :       0 2 | 1             <- loaded in PetscSectionLoad()
  sectionA->atlasDof             :       1 3 | 1             <- loaded in PetscSectionLoad()
  sectionA's global point numbers:       0 2 | 3             <- loaded in DMPlexSectionLoad()
  [0, NX)                        :       0 1 | 2 3           <- conceptual partition used in globalToLocalPointSF
  sectionB's global point numbers:     0 1 3 | 3 2           <- associated with [0, NX) by globalToLocalPointSF
  sectionB->atlasDof             :     1 0 1 | 1 3
  sectionB->atlasOff (no perm)   :     0 1 1 | 0 1
  vecB (local)                   :   [.0 .4] | [.4 .1 .2 .3] <- to be constructed by calling DMPlexLocalVectorLoad() with localDofSF
  vecB (global)                  :    [.0 .4 | .1 .2 .3]     <- to be constructed by calling DMPlexGlobalVectorLoad() with globalDofSF
where “|” represents a partition of loaded data, and global point 3 is assumed to be owned by rank 0.
See Also#
DMPlex: Unstructured Grids, DM, DMPLEX, DMLoad(), DMPlexTopologyLoad(), DMPlexCoordinatesLoad(), DMPlexLabelsLoad(), DMPlexGlobalVectorLoad(), DMPlexLocalVectorLoad(), PetscSectionLoad(), DMPlexSectionView(), PetscSF, PetscViewer
Level#
advanced
Location#
Examples#
Index of all DMPlex routines
Table of Contents for all manual pages
Index of all manual pages