#include <EpetraExt_Permutation.h>
Inheritance diagram for EpetraExt::Permutation< T >:
Public Types | |
typedef EpetraExt::SameTypeTransform< T >::TransformTypeRef | OutputRef |
typedef EpetraExt::SameTypeTransform< T >::TransformTypeRef | InputRef |
typedef EpetraExt::SameTypeTransform< T >::TransformTypePtr | OutputPtr |
typedef EpetraExt::SameTypeTransform< T >::TransformTypePtr | InputPtr |
Public Member Functions | |
Permutation (Epetra_DataAccess CV, const Epetra_BlockMap &map, int *permutation) | |
Constructor. | |
Permutation (const Epetra_BlockMap &map) | |
Constructor. | |
Permutation (const Permutation< T > &src) | |
Copy Constructor. | |
virtual | ~Permutation () |
Destructor. | |
OutputRef | operator() (InputRef orig) |
This method creates a new object which is a permuted copy of the input argument. | |
OutputRef | operator() (InputRef orig, bool column_permutation) |
This method creates a new object which is a permuted copy of the input argument. |
As described in "Matrix Computations" (Golub and Van Loan), a permutation matrix is the identity matrix with its rows re-ordered. The permutation is internally stored as an integer vector p, where p[i] is the column-index of the "1" in P's i-th row. Consider the example of permuting a matrix A by applying the permutation matrix P to form the result B. i.e., B = PA. If p[i] = j, then row j of A becomes row i of B.
This Permutation class is templated on the type of the object to be permuted. However, not all objects are eligible to be template parameters. Currently the following objects may be used: Epetra_CrsMatrix, Epetra_CrsGraph and Epetra_MultiVector.
A test program which exercises this Permutation class is located in the directory packages/epetraext/test/Permutation.
Implementation Notes: Permutation currently inherits StructuralSameTypeTransform, which in turn inherits Transform through SameTypeTransform. Permutation, and its base classes, are templates. A couple of noteworthy consequences result from this:
1. A separate instantiation of Permutation must be created for each type of object to be permuted. Example: Epetra_CrsGraph& graph = ... Epetra_CrsMatrix& A = ... Permutation<Epetra_CrsGraph> graph_perm(...); Permutation<Epetra_CrsMatrix> matrix_perm(...);
Epetra_CrsMatrix& PA = matrix_perm(A); Epetra_CrsGraph& Pgraph = graph_perm(graph);
2. Following the semantics of Transform, when the Permutation class is used to create a new permuted copy of an object, ownership of the new copy is retained by Permutation. Permutation will destroy the new object. This means that only one object should be permuted by a Permutation instance.
It is not clear that these are desirable behaviors for permutations. It is possible that Permutation will be altered to remove these limitations, as follows:
1. If Permutation doesn't inherit Transform, then Permutation need not be a template and instead we could either overload or template-ize the operator() method member. This would allow a single instantiation of Permutation to be used for permuting all of the eligible target types.
2. Allowing the caller (user) to take ownership of the newly-produced permuted objects would allow a single Permutation instance to be used repeatedly since it would no longer need to hold a pointer to the new object for later deletion.
Then, example usage could look like this: Epetra_CrsMatrix& A = ... Epetra_MultiVector& v = ... Permutation P(...);
Epetra_CrsMatrix PA = P(A); Epetra_MultiVector Pv = P(v);
Questions and comments about this class may be directed to Alan Williams.
Definition at line 103 of file EpetraExt_Permutation.h.
typedef EpetraExt::SameTypeTransform<T>::TransformTypeRef EpetraExt::Permutation< T >::OutputRef |
Definition at line 134 of file EpetraExt_Permutation.h.
typedef EpetraExt::SameTypeTransform<T>::TransformTypeRef EpetraExt::Permutation< T >::InputRef |
Definition at line 135 of file EpetraExt_Permutation.h.
typedef EpetraExt::SameTypeTransform<T>::TransformTypePtr EpetraExt::Permutation< T >::OutputPtr |
Definition at line 136 of file EpetraExt_Permutation.h.
typedef EpetraExt::SameTypeTransform<T>::TransformTypePtr EpetraExt::Permutation< T >::InputPtr |
Definition at line 137 of file EpetraExt_Permutation.h.
EpetraExt::Permutation< T >::Permutation | ( | Epetra_DataAccess | CV, | |
const Epetra_BlockMap & | map, | |||
int * | permutation | |||
) |
Constructor.
CV | Set to either Copy or View. | |
map | Defines the index space to be permuted. | |
permutation | Array defining the permutation. The length of this array must be 'map.NumMyElements()'. This array is the local portion of the 'p' vector described in the 'Detailed Description' section. |
Definition at line 363 of file EpetraExt_Permutation_impl.h.
EpetraExt::Permutation< T >::Permutation | ( | const Epetra_BlockMap & | map | ) |
Constructor.
This constructor creates an empty permutation object. The contents must then be set using regular Epetra_IntVector methods.
map | Defines the index space to be permuted. |
Definition at line 377 of file EpetraExt_Permutation_impl.h.
EpetraExt::Permutation< T >::Permutation | ( | const Permutation< T > & | src | ) |
Copy Constructor.
EpetraExt::Permutation< T >::~Permutation | ( | ) | [virtual] |
OutputRef EpetraExt::Permutation< T >::operator() | ( | InputRef | orig | ) |
This method creates a new object which is a permuted copy of the input argument.
Notes:
orig | Input Object to be permuted. |
OutputRef EpetraExt::Permutation< T >::operator() | ( | InputRef | orig, | |
bool | column_permutation | |||
) |
This method creates a new object which is a permuted copy of the input argument.
The same notes apply to this method (regarding collective communications etc.) as to the row-permutation operator method above.
orig | Input Object to be permuted. | |
column_permutation | Optional Input, defaults to false if not provided. A value of false means that a row-permutation will be performed (result = P*orig), a value of true means that a column-permutation will be performed (result = orig*P). |