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Reference documentation for deal.II version Git ac854ef673 2021-03-06 10:09:45 +0100
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#include <deal.II/lac/precondition.h>
Public Member Functions | |
AdditionalData (const unsigned int degree=1, const double smoothing_range=0., const unsigned int eig_cg_n_iterations=8, const double eig_cg_residual=1e-2, const double max_eigenvalue=1) | |
AdditionalData & | operator= (const AdditionalData &other_data) |
Public Attributes | |
unsigned int | degree |
double | smoothing_range |
unsigned int | eig_cg_n_iterations |
double | eig_cg_residual |
double | max_eigenvalue |
AffineConstraints< double > | constraints |
std::shared_ptr< PreconditionerType > | preconditioner |
Standardized data struct to pipe additional parameters to the preconditioner.
Definition at line 1003 of file precondition.h.
PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::AdditionalData | ( | const unsigned int | degree = 1 , |
const double | smoothing_range = 0. , |
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const unsigned int | eig_cg_n_iterations = 8 , |
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const double | eig_cg_residual = 1e-2 , |
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const double | max_eigenvalue = 1 |
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) |
Constructor.
AdditionalData& PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::operator= | ( | const AdditionalData & | other_data | ) |
Copy assignment operator.
unsigned int PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::degree |
This determines the degree of the Chebyshev polynomial. The degree of the polynomial gives the number of matrix-vector products to be performed for one application of the vmult() operation. Degree one corresponds to a damped Jacobi method.
If the degree is set to numbers::invalid_unsigned_int, the algorithm will automatically determine the number of necessary iterations based on the usual Chebyshev error formula as mentioned in the discussion of the main class.
Definition at line 1031 of file precondition.h.
double PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::smoothing_range |
This sets the range between the largest eigenvalue in the matrix and the smallest eigenvalue to be treated. If the parameter is set to a number less than 1, an estimate for the largest and for the smallest eigenvalue will be calculated internally. For a smoothing range larger than one, the Chebyshev polynomial will act in the interval \([\lambda_\mathrm{max}/ \tt{smoothing\_range}, \lambda_\mathrm{max}]\), where \(\lambda_\mathrm{max}\) is an estimate of the maximum eigenvalue of the matrix. A choice of smoothing_range
between 5 and 20 is useful in case the preconditioner is used as a smoother in multigrid.
Definition at line 1044 of file precondition.h.
unsigned int PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::eig_cg_n_iterations |
Maximum number of CG iterations performed for finding the maximum eigenvalue. If set to zero, no computations are performed. Instead, the user must supply a largest eigenvalue via the variable PreconditionChebyshev::AdditionalData::max_eigenvalue.
Definition at line 1052 of file precondition.h.
double PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::eig_cg_residual |
Tolerance for CG iterations performed for finding the maximum eigenvalue.
Definition at line 1058 of file precondition.h.
double PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::max_eigenvalue |
Maximum eigenvalue to work with. Only in effect if eig_cg_n_iterations
is set to zero, otherwise this parameter is ignored.
Definition at line 1065 of file precondition.h.
AffineConstraints<double> PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::constraints |
Constraints to be used for the operator given. This variable is used to zero out the correct entries when creating an initial guess.
Definition at line 1071 of file precondition.h.
std::shared_ptr<PreconditionerType> PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::preconditioner |
Stores the preconditioner object that the Chebyshev is wrapped around.
Definition at line 1076 of file precondition.h.