Reference documentation for deal.II version Git 4e8af90f34 20220122 18:32:44 +0100

#include <deal.II/lac/petsc_precondition.h>
Public Member Functions  
AdditionalData (const unsigned int symmetric=1, const unsigned int n_levels=1, const double threshold=0.1, const double filter=0.05, const bool output_details=false)  
Public Attributes  
unsigned int  symmetric 
unsigned int  n_levels 
double  threshold 
double  filter 
bool  output_details 
Standardized data struct to pipe additional flags to the preconditioner.
Definition at line 815 of file petsc_precondition.h.
PETScWrappers::PreconditionParaSails::AdditionalData::AdditionalData  (  const unsigned int  symmetric = 1 , 
const unsigned int  n_levels = 1 , 

const double  threshold = 0.1 , 

const double  filter = 0.05 , 

const bool  output_details = false 

) 
Constructor.
Definition at line 664 of file petsc_precondition.cc.
unsigned int PETScWrappers::PreconditionParaSails::AdditionalData::symmetric 
This parameter specifies the type of problem to solve:
0
: nonsymmetric and/or indefinite problem, and nonsymmetric preconditioner 1
: SPD problem, and SPD (factored) preconditioner 2
: nonsymmetric, definite problem, and SPD (factored) preconditioner Default is symmetric = 1
.
Definition at line 837 of file petsc_precondition.h.
unsigned int PETScWrappers::PreconditionParaSails::AdditionalData::n_levels 
The sparsity pattern used for the approximate inverse is the pattern of a power B^m
where B
has been sparsified from the given matrix A
, n_level
is equal to m+1
. Default value is n_levels = 1
.
Definition at line 845 of file petsc_precondition.h.
double PETScWrappers::PreconditionParaSails::AdditionalData::threshold 
Sparsification is performed by dropping nonzeros which are smaller than thresh
in magnitude. Lower values of thresh
lead to more accurate, but also more expensive preconditioners. Default value is thresh = 0.1
. Setting thresh < 0
a threshold is selected automatically, such that thresh
represents the fraction of nonzero elements that are dropped. For example, if thresh = 0.9
, then B
will contain about ten percent of the nonzeros of the given matrix A
.
Definition at line 857 of file petsc_precondition.h.
double PETScWrappers::PreconditionParaSails::AdditionalData::filter 
Filtering is a postprocessing procedure, filter
represents a fraction of nonzero elements that are dropped after creating the approximate inverse sparsity pattern. Default value is filter = 0.05
. Setting filter < 0
a value is selected automatically, such that filter
represents the fraction of nonzero elements that are dropped. For example, if thresh = 0.9
, then about 90 percent of the entries in the computed approximate inverse are dropped.
Definition at line 869 of file petsc_precondition.h.
bool PETScWrappers::PreconditionParaSails::AdditionalData::output_details 
Setting this flag to true produces output from HYPRE, when the preconditioner is constructed.
Definition at line 875 of file petsc_precondition.h.