MFEM  v3.3
Finite element discretization library
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mfem::ConstrainedOperator Class Reference

Square Operator for imposing essential boundary conditions using only the action, Mult(), of a given unconstrained Operator. More...

#include <operator.hpp>

Inheritance diagram for mfem::ConstrainedOperator:
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Collaboration diagram for mfem::ConstrainedOperator:
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Public Member Functions

 ConstrainedOperator (Operator *A, const Array< int > &list, bool own_A=false)
 Constructor from a general Operator and a list of essential indices/dofs. More...
 
void EliminateRHS (const Vector &x, Vector &b) const
 Eliminate "essential boundary condition" values specified in x from the given right-hand side b. More...
 
virtual void Mult (const Vector &x, Vector &y) const
 Constrained operator action. More...
 
virtual ~ConstrainedOperator ()
 Destructor: destroys the unconstrained Operator A if own_A is true. More...
 
- Public Member Functions inherited from mfem::Operator
 Operator (int s=0)
 Construct a square Operator with given size s (default 0). More...
 
 Operator (int h, int w)
 Construct an Operator with the given height (output size) and width (input size). More...
 
int Height () const
 Get the height (size of output) of the Operator. Synonym with NumRows(). More...
 
int NumRows () const
 Get the number of rows (size of output) of the Operator. Synonym with Height(). More...
 
int Width () const
 Get the width (size of input) of the Operator. Synonym with NumCols(). More...
 
int NumCols () const
 Get the number of columns (size of input) of the Operator. Synonym with Width(). More...
 
virtual void MultTranspose (const Vector &x, Vector &y) const
 Action of the transpose operator: y=A^t(x). The default behavior in class Operator is to generate an error. More...
 
virtual OperatorGetGradient (const Vector &x) const
 Evaluate the gradient operator at the point x. The default behavior in class Operator is to generate an error. More...
 
virtual const OperatorGetProlongation () const
 Prolongation operator from linear algebra (linear system) vectors, to input vectors for the operator. NULL means identity. More...
 
virtual const OperatorGetRestriction () const
 Restriction operator from input vectors for the operator to linear algebra (linear system) vectors. NULL means identity. More...
 
void FormLinearSystem (const Array< int > &ess_tdof_list, Vector &x, Vector &b, Operator *&A, Vector &X, Vector &B, int copy_interior=0)
 Form a constrained linear system using a matrix-free approach. More...
 
virtual void RecoverFEMSolution (const Vector &X, const Vector &b, Vector &x)
 Reconstruct a solution vector x (e.g. a GridFunction) from the solution X of a constrained linear system obtained from Operator::FormLinearSystem(). More...
 
void PrintMatlab (std::ostream &out, int n=0, int m=0) const
 Prints operator with input size n and output size m in Matlab format. More...
 
virtual ~Operator ()
 Virtual destructor. More...
 

Protected Attributes

Array< int > constraint_list
 List of constrained indices/dofs. More...
 
OperatorA
 The unconstrained Operator. More...
 
bool own_A
 Ownership flag for A. More...
 
Vector z
 
Vector w
 Auxiliary vectors. More...
 
- Protected Attributes inherited from mfem::Operator
int height
 Dimension of the output / number of rows in the matrix. More...
 
int width
 Dimension of the input / number of columns in the matrix. More...
 

Additional Inherited Members

- Public Types inherited from mfem::Operator
enum  Type {
  MFEM_SPARSEMAT, HYPRE_PARCSR, PETSC_MATAIJ, PETSC_MATIS,
  PETSC_MATSHELL, PETSC_MATNEST
}
 Enumeration defining IDs for some classes derived from Operator. More...
 

Detailed Description

Square Operator for imposing essential boundary conditions using only the action, Mult(), of a given unconstrained Operator.

Square operator constrained by fixing certain entries in the solution to given "essential boundary condition" values. This class is used by the general, matrix-free system formulation of Operator::FormLinearSystem.

Definition at line 382 of file operator.hpp.

Constructor & Destructor Documentation

mfem::ConstrainedOperator::ConstrainedOperator ( Operator A,
const Array< int > &  list,
bool  own_A = false 
)

Constructor from a general Operator and a list of essential indices/dofs.

Specify the unconstrained operator *A and a list of indices to constrain, i.e. each entry list[i] represents an essential-dof. If the ownership flag own_A is true, the operator *A will be destroyed when this object is destroyed.

Definition at line 98 of file operator.cpp.

virtual mfem::ConstrainedOperator::~ConstrainedOperator ( )
inlinevirtual

Destructor: destroys the unconstrained Operator A if own_A is true.

Definition at line 422 of file operator.hpp.

Member Function Documentation

void mfem::ConstrainedOperator::EliminateRHS ( const Vector x,
Vector b 
) const

Eliminate "essential boundary condition" values specified in x from the given right-hand side b.

Performs the following steps:

z = A((0,x_b));  b_i -= z_i;  b_b = x_b;

where the "_b" subscripts denote the essential (boundary) indices/dofs of the vectors, and "_i" – the rest of the entries.

Definition at line 107 of file operator.cpp.

void mfem::ConstrainedOperator::Mult ( const Vector x,
Vector y 
) const
virtual

Constrained operator action.

Performs the following steps:

z = A((x_i,0));  y_i = z_i;  y_b = x_b;

where the "_b" subscripts denote the essential (boundary) indices/dofs of the vectors, and "_i" – the rest of the entries.

Implements mfem::Operator.

Definition at line 126 of file operator.cpp.

Member Data Documentation

Operator* mfem::ConstrainedOperator::A
protected

The unconstrained Operator.

Definition at line 386 of file operator.hpp.

Array<int> mfem::ConstrainedOperator::constraint_list
protected

List of constrained indices/dofs.

Definition at line 385 of file operator.hpp.

bool mfem::ConstrainedOperator::own_A
protected

Ownership flag for A.

Definition at line 387 of file operator.hpp.

Vector mfem::ConstrainedOperator::w
mutableprotected

Auxiliary vectors.

Definition at line 388 of file operator.hpp.

Vector mfem::ConstrainedOperator::z
mutableprotected

Definition at line 388 of file operator.hpp.


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