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Reference documentation for deal.II version 9.1.0-pre
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Reference documentation for deal.II version 9.1.0-pre
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#include <deal.II/lac/precondition.h>
Public Member Functions | |
| AdditionalData (const unsigned int degree=0, const double smoothing_range=0., const bool nonzero_starting=false, const unsigned int eig_cg_n_iterations=8, const double eig_cg_residual=1e-2, const double max_eigenvalue=1) | |
Public Attributes | |
| unsigned int | degree |
| double | smoothing_range |
| bool | nonzero_starting |
| unsigned int | eig_cg_n_iterations |
| double | eig_cg_residual |
| double | max_eigenvalue |
| VectorType | matrix_diagonal_inverse |
| std::shared_ptr< PreconditionerType > | preconditioner |
Standardized data struct to pipe additional parameters to the preconditioner.
Definition at line 973 of file precondition.h.
| PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::AdditionalData | ( | const unsigned int | degree = 0, |
| const double | smoothing_range = 0., |
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| const bool | nonzero_starting = false, |
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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.
| 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 zero 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 996 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 1009 of file precondition.h.
| bool PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::nonzero_starting |
When this flag is set to true, it enables the method vmult(dst, src) to use non-zero data in the vector dst, appending to it the Chebyshev corrections. This can be useful in some situations (e.g. when used for high-frequency error smoothing in a multigrid algorithm), but not the way the solver classes expect a preconditioner to work (where one ignores the content in dst for the preconditioner application).
Definition at line 1023 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 and the eigenvalues according to the given input are used instead.
Definition at line 1030 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 1036 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 1043 of file precondition.h.
| VectorType PreconditionChebyshev< MatrixType, VectorType, PreconditionerType >::AdditionalData::matrix_diagonal_inverse |
Stores the inverse of the diagonal of the underlying matrix.
preconditioner defined below instead. Definition at line 1050 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 1055 of file precondition.h.
1.8.11