Two grid operator for AMG with Krylov cycle.
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#include <dune/istl/paamg/kamg.hh>
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typedef AMG::Domain | domain_type |
| The domain type of the preconditioner.
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typedef AMG::Range | range_type |
| The range type of the preconditioner.
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typedef X::field_type | field_type |
| The field type of the preconditioner.
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template<class
AMG>
class Dune::Amg::KAmgTwoGrid< AMG >
Two grid operator for AMG with Krylov cycle.
- Template Parameters
-
AMG | The type of the underlying agglomeration AMG. |
◆ KAmgTwoGrid()
Constructor.
- Parameters
-
amg | The underlying amg. It is used as the storage for the hierarchic data structures. |
coarseSolver | The solver used for the coarse grid correction. |
◆ apply() [1/2]
Apply one step of the preconditioner to the system A(v)=d.
On entry v=0 and d=b-A(x) (although this might not be computed in that way. On exit v contains the update, i.e one step computes \( v = M^{-1} d \) where \( M \) is the approximate inverse of the operator \( A \) characterizing the preconditioner.
- Parameters
-
[out] | v | The update to be computed |
| d | The current defect. |
◆ apply() [2/2]
Apply one step of the preconditioner to the system A(v)=d.
On entry v=0 and d=b-A(x) (although this might not be computed in that way. On exit v contains the update, i.e one step computes \( v = M^{-1} d \) where \( M \) is the approximate inverse of the operator \( A \) characterizing the preconditioner.
- Parameters
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[out] | v | The update to be computed |
| d | The current defect. |
References Dune::Amg::postsmooth(), and Dune::Amg::presmooth().
◆ coarseSolver()
Get a pointer to the coarse grid solver.
- Returns
- The coarse grid solver.
◆ post() [1/2]
Clean up.
This method is called after the last apply call for the linear system to be solved. Memory may be deallocated safely here. x is the solution of the linear equation.
- Parameters
-
x | The right hand side of the equation. |
◆ post() [2/2]
Clean up.
This method is called after the last apply call for the linear system to be solved. Memory may be deallocated safely here. x is the solution of the linear equation.
- Parameters
-
x | The right hand side of the equation. |
◆ pre() [1/2]
Prepare the preconditioner.
A solver solves a linear operator equation A(x)=b by applying one or several steps of the preconditioner. The method pre() is called before the first apply operation. b and x are right hand side and solution vector of the linear system respectively. It may. e.g., scale the system, allocate memory or compute a (I)LU decomposition. Note: The ILU decomposition could also be computed in the constructor or with a separate method of the derived method if several linear systems with the same matrix are to be solved.
- Note
- if a preconditioner is copied (e.g. for a second thread) again the pre() method has to be called to ensure proper memory management.
X x(0.0);
Y b = ...;
prec.pre(x,b);
prec.apply(x,b);
prec.post(x);
Base class for matrix free definition of preconditioners.
Definition: preconditioner.hh:33
- Parameters
-
x | The left hand side of the equation. |
b | The right hand side of the equation. |
◆ pre() [2/2]
Prepare the preconditioner.
A solver solves a linear operator equation A(x)=b by applying one or several steps of the preconditioner. The method pre() is called before the first apply operation. b and x are right hand side and solution vector of the linear system respectively. It may. e.g., scale the system, allocate memory or compute a (I)LU decomposition. Note: The ILU decomposition could also be computed in the constructor or with a separate method of the derived method if several linear systems with the same matrix are to be solved.
- Note
- if a preconditioner is copied (e.g. for a second thread) again the pre() method has to be called to ensure proper memory management.
X x(0.0);
Y b = ...;
prec.pre(x,b);
prec.apply(x,b);
prec.post(x);
- Parameters
-
x | The left hand side of the equation. |
b | The right hand side of the equation. |
◆ setLevelContext()
Set the level context pointer.
- Parameters
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p | The pointer to set it to. |
The documentation for this class was generated from the following files: