Epetra_MapColoring Class Reference

Epetra_MapColoring: A class for coloring Epetra_Map and Epetra_BlockMap objects. More...

#include <Epetra_MapColoring.h>

Inheritance diagram for Epetra_MapColoring:

[legend]Collaboration diagram for Epetra_MapColoring:[legend]List of all members.

Public Member Functions
Constructors/destructors.
	Epetra_MapColoring (const Epetra_BlockMap &Map, const int DefaultColor=0)
	Epetra_MapColoring basic constructor.
	Epetra_MapColoring (const Epetra_BlockMap &Map, int *ElementColors, const int DefaultColor=0)
	Epetra_MapColoring constructor.
	Epetra_MapColoring (const Epetra_MapColoring &Source)
	Epetra_MapColoring copy constructor.
virtual	~Epetra_MapColoring ()
	Epetra_MapColoring destructor.
Set Color methods.
int &	operator[] (int LID)
	LID element color assignment method.
int &	operator() (int GID)
	GID element color assignment method, Note: Valid only for GIDs owned by calling processor.
Local/Global color accessor methods.
const int &	operator[] (int LID) const
	LID element color access method.
const int &	operator() (int GID) const
	GID element color assignment method, Note: Valid only for GIDs owned by calling processor.
Color Information Access Methods.
int	NumColors () const
	Returns number of colors on the calling processor.
int	MaxNumColors () const
	Returns maximum over all processors of the number of colors.
int *	ListOfColors () const
	Array of length NumColors() containing List of color values used in this coloring.
int	DefaultColor () const
	Returns default color.
int	NumElementsWithColor (int Color) const
	Returns number of map elements on calling processor having specified Color.
int *	ColorLIDList (int Color) const
	Returns pointer to array of Map LIDs associated with the specified color.
int *	ElementColors () const
	Returns pointer to array of the colors associated with the LIDs on the calling processor.
Epetra_Map and Epetra_BlockMap generators.
Epetra_Map *	GenerateMap (int Color) const
	Generates an Epetra_Map of the GIDs associated with the specified color.
Epetra_BlockMap *	GenerateBlockMap (int Color) const
	Generates an Epetra_BlockMap of the GIDs associated with the specified color.
I/O methods
virtual void	Print (ostream &os) const
	Print method.

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Detailed Description

Epetra_MapColoring: A class for coloring Epetra_Map and Epetra_BlockMap objects.

This class allows the user to associate an integer value, i.e., a color, to each element of an existing Epetra_Map or Epetra_BlockMap object. Colors may be assigned at construction, or via set methods. Any elements that are not explicitly assigned a color are assigned the color 0 (integer zero).

This class has the following features:

• A color (arbitrary integer label) can be associated locally with each element of a map. Color assignment can be done
  1. all-at-once via the constructor, or
  2. via operator[] (using LIDs) one-at-a-time
  3. operator() (using GIDs) one-at-a-time
  4. or some combination of the above.

  Any element that is not explicitly colored takes on the default color. The default color is implicitly zero, unless specified differently at the time of construction.

• Color information may be accessed in the following ways:
  1. By local element ID (LID) - Returns the color of a specified LID, where the LID is associated with the Epetra_Map or BlockMap that was passed in to the Epetra_MapColoring constructor.
  2. By global element ID (GID) - Returns the color of the specified GID. There two methods for accessing GIDs, one assumes the request is for GIDs owned by the calling processor, the second allows arbitrary requested for GIDs, as long as the GID is defined on some processor for the Epetra_Map or Epetra_BlockMap.
  3. By color groups - Elements are grouped by color so that all elements of a given color can be accessed.
  4. Epetra_Map/Epetra_BlockMap pointers for a specified color - This facilitates use of coloring with Epetra distributed objects that are distributed via the map that was colored. For example, if users want to work with all rows of a matrix that have a certain color, they can create a map for that color and use it to access only those rows.

• The Epetra_MapColoring class implements the Epetra_DistObject interface. Therefore, a map coloring can be computed for a map with a given distribution and then redistributed across the parallel machine. For example, it would be possible to compute a map coloring on a single processor (perhaps because the algorithm for computing the color assignment is too difficult to implement in parallel or because it is cheap to run and not worth parallelizing), and then re-distribute the coloring using an Epetra_Export or Epetra_Import object.

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Constructor & Destructor Documentation

Epetra_MapColoring::Epetra_MapColoring (  const Epetra_BlockMap &  Map, const int  DefaultColor = 0 )

Epetra_MapColoring basic constructor. Parameters: In  Map - An Epetra_Map or Epetra_BlockMap (Note: Epetra_BlockMap is a base class of Epetra_Map, so either can be passed in to this constructor. In  DefaultColor - The integer value to use as the default color for this map. This constructor will initially define the color of all map elements to the default color. Returns: Pointer to a Epetra_MapColoring object.

Epetra_MapColoring::Epetra_MapColoring (  const Epetra_BlockMap &  Map, int *  ElementColors, const int  DefaultColor = 0 )

Epetra_MapColoring constructor. Parameters: In  Map - An Epetra_Map or Epetra_BlockMap (Note: Epetra_BlockMap is a base class of Epetra_Map, so either can be passed in to this constructor. In  ElementColors - Array of dimension Map.NumMyElements() containing the list of colors that should be assigned the map elements on this processor. If this argument is set to 0 (zero), all elements will initially be assigned color 0 (zero). Element colors can be modified by using methods described below. In  DefaultColor - The color that will be assigned by default when no other value is specified. This value has no meaning for this constructor, but is used by certain methods now and in the future. Returns: Pointer to a Epetra_MapColoring object.

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Member Function Documentation

int* Epetra_MapColoring::ColorLIDList (  int  Color  )  const

Returns pointer to array of Map LIDs associated with the specified color. Returns a pointer to a list of Map LIDs associated with the specified color. This is a purely local list with no information about other processors. If there are no LIDs associated with the specified color, the pointer is set to zero.

int* Epetra_MapColoring::ElementColors (   )  const [inline]

Returns pointer to array of the colors associated with the LIDs on the calling processor. Returns a pointer to the list of colors associated with the elements on this processor such that ElementColor[LID] is the color assigned to that LID.

Epetra_BlockMap* Epetra_MapColoring::GenerateBlockMap (  int  Color  )  const

Generates an Epetra_BlockMap of the GIDs associated with the specified color. This method will create an Epetra_BlockMap such that on each processor the GIDs associated with the specified color will be part of the map on that processor. Note that this method will generate an Epetra_BlockMap such that each element as the same element size as the corresponding element of map associated with the map coloring. Once the map is generated, the user is responsible for deleting it.

Epetra_Map* Epetra_MapColoring::GenerateMap (  int  Color  )  const

Generates an Epetra_Map of the GIDs associated with the specified color. This method will create an Epetra_Map such that on each processor the GIDs associated with the specified color will be part of the map on that processor. Note that this method always generates an Epetra_Map, not an Epetra_BlockMap, even if the map associated with this map coloring is a block map. Once the map is generated, the user is responsible for deleting it.

int* Epetra_MapColoring::ListOfColors (   )  const [inline]

Array of length NumColors() containing List of color values used in this coloring. Color values can be arbitrary integer values. As a result, a user of a previously constructed MapColoring object may need to know exactly which color values are present. This array contains that information as a sorted list of integer values.

const int& Epetra_MapColoring::operator() (  int  GID  )  const [inline]

GID element color assignment method, Note: Valid only for GIDs owned by calling processor. Allows color assignment of specified GID only if the GID is owned by map on the calling processor. If you are unsure about the ownership, check by using the MyGID() method on the map object. Returns: MapColor(GID).

int& Epetra_MapColoring::operator() (  int  GID  )  [inline]

GID element color assignment method, Note: Valid only for GIDs owned by calling processor. Allows color assignment of specified GID only if the GID is owned by map on the calling processor. If you are unsure about the ownership of a GID, check by using the MyGID() method. MyGID(GID) returns true if the GID is owned by the calling processor. Returns: MapColor(GID).

const int& Epetra_MapColoring::operator[] (  int  LID  )  const [inline]

LID element color access method. Returns color of ith LID: colormap[i] = color Returns: MapColor[LID].

int& Epetra_MapColoring::operator[] (  int  LID  )  [inline]

LID element color assignment method. Allows color assignment of ith LID: colormap[i] = color Returns: MapColor(LID).

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The documentation for this class was generated from the following file:

• Epetra_MapColoring.h

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