Reference documentation for deal.II version 9.4.0
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Public Member Functions | Public Attributes | List of all members

#include <deal.II/lac/trilinos_precondition.h>

Public Member Functions

 AdditionalData (const double ilut_drop=0., const unsigned int ilut_fill=0, const double ilut_atol=0., const double ilut_rtol=1., const unsigned int overlap=0)

Public Attributes

double ilut_drop
unsigned int ilut_fill
double ilut_atol
double ilut_rtol
unsigned int overlap

Detailed Description

Standardized data struct to pipe additional parameters to the preconditioner. The Trilinos ILU-T decomposition allows for some fill- in, so it actually is a threshold incomplete LU factorization. The amount of fill-in, and hence, the amount of memory used by this preconditioner, is controlled by the parameters ilut_drop and ilut_fill, which specifies a threshold about which values should form the incomplete factorization and the level of additional fill-in. When forming the preconditioner, for certain problems bad conditioning (or just bad luck) can cause the preconditioner to be very poorly conditioned. Hence it can help to add diagonal perturbations to the original matrix and form the preconditioner for this slightly better matrix. ilut_atol is an absolute perturbation that is added to the diagonal before forming the prec, and ilu_rtol is a scaling factor \(rtol \geq 1\). The last parameter specifies the overlap of the partitions when the preconditioner runs in parallel.

Definition at line 1099 of file trilinos_precondition.h.

The documentation for this struct was generated from the following files: