Reference documentation for deal.II version Git cb0bd54b52 20190921 16:31:22 0400

#include <deal.II/lac/trilinos_precondition.h>
Public Member Functions  
AdditionalData (const unsigned int block_size=1, const std::string &block_creation_type="linear", const double omega=1, const double min_diagonal=0, const unsigned int n_sweeps=1)  
Public Attributes  
unsigned int  block_size 
std::string  block_creation_type 
double  omega 
double  min_diagonal 
unsigned int  n_sweeps 
Standardized data struct to pipe additional flags to the preconditioner. The parameter block_size
sets the size of small blocks. It is recommended to choose this parameter not too large (a few hundreds at most) since this implementation uses a dense matrix for the block. The parameter block_creation_type
allows to pass the strategy for finding the blocks to Ifpack. The parameter omega
specifies the relaxation parameter in the SOR preconditioner. The parameter min_diagonal
can be used to make the application of the preconditioner also possible when some diagonal elements are zero. In a default application this would mean that we divide by zero, so by setting the parameter min_diagonal
to a small nonzero value the SOR will work on a matrix that is not too far away from the one we want to treat. Finally, overlap
governs the overlap of the partitions when the preconditioner runs in parallel, forming a socalled additive Schwarz preconditioner.
Definition at line 558 of file trilinos_precondition.h.
TrilinosWrappers::PreconditionBlockJacobi::AdditionalData::AdditionalData  (  const unsigned int  block_size = 1 , 
const std::string &  block_creation_type = "linear" , 

const double  omega = 1 , 

const double  min_diagonal = 0 , 

const unsigned int  n_sweeps = 1 

) 
Constructor. By default, use a block size of 1, use linear subdivision of the rows, set the damping parameter to one, and do not modify the diagonal.
Definition at line 259 of file trilinos_precondition.cc.
unsigned int TrilinosWrappers::PreconditionBlockJacobi::AdditionalData::block_size 
This specifies the size of blocks.
Definition at line 574 of file trilinos_precondition.h.
std::string TrilinosWrappers::PreconditionBlockJacobi::AdditionalData::block_creation_type 
Strategy for creation of blocks passed on to Ifpack block relaxation (variable 'partitioner: type') with this string as the given value. Available types in Ifpack include "linear" (i.e., divide the local range of the matrix in slices of the block size), "greedy" "metis". For a full list, see the documentation of Ifpack.
Definition at line 583 of file trilinos_precondition.h.
double TrilinosWrappers::PreconditionBlockJacobi::AdditionalData::omega 
This specifies the (over) relaxation parameter in the Jacobi preconditioner.
Definition at line 589 of file trilinos_precondition.h.
double TrilinosWrappers::PreconditionBlockJacobi::AdditionalData::min_diagonal 
This specifies the minimum value the diagonal elements should have. This might be necessary when the block Jacobi preconditioner is used on matrices with zero diagonal elements. In that case, a straight forward application would not be possible since we divide by the diagonal element.
Definition at line 598 of file trilinos_precondition.h.
unsigned int TrilinosWrappers::PreconditionBlockJacobi::AdditionalData::n_sweeps 
Sets how many times the given operation should be applied during the vmult() operation.
Definition at line 604 of file trilinos_precondition.h.