6.3.3. Tpetra Preconditioners

6.3.3.1. Muelu Preconditioner

Scope: Cg Solver
Summary: Use a MueLu preconditioner.

begin Muelu Preconditioner

   Xml File {=} value

end Muelu Preconditioner

6.3.3.1.1. Line Commands

Xml File

Syntax: Xml File {=} value
Summary: Supply the name of an XML file containing a MueLu parameter list.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	string	–

6.3.3.2. Jacobi Preconditioner

Scope: Cg Solver
Summary: Use a Jacobi preconditioner.

begin Jacobi Preconditioner

   Damping Factor {=} value

   Number Of Sweeps {=} value

end Jacobi Preconditioner

6.3.3.2.1. Line Commands

Damping Factor

Syntax: Damping Factor {=} value
Summary: Set the relaxation damping factor.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	real	1

Number Of Sweeps

Syntax: Number Of Sweeps {=} value
Summary: Set the number of relaxation sweeps to perform.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	3

6.3.3.3. Sgs2 Preconditioner

Scope: Cg Solver
Summary: Use a Two-stage symmetric Gauss-Seidel preconditioner.

begin Sgs2 Preconditioner

   Damping Factor {=} value

   Number Of Sweeps {=} value

end Sgs2 Preconditioner

6.3.3.3.1. Line Commands

Damping Factor

Syntax: Damping Factor {=} value
Summary: Set the relaxation damping factor.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	real	1

Number Of Sweeps

Syntax: Number Of Sweeps {=} value
Summary: Set the number of relaxation sweeps to perform.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	3

6.3.3.4. Sgs Preconditioner

Scope: Cg Solver
Summary: Use a symmetric Gauss-Seidel preconditioner.

begin Sgs Preconditioner

   Damping Factor {=} value

   Number Of Sweeps {=} value

end Sgs Preconditioner

6.3.3.4.1. Line Commands

Damping Factor

Syntax: Damping Factor {=} value
Summary: Set the relaxation damping factor.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	real	1

Number Of Sweeps

Syntax: Number Of Sweeps {=} value
Summary: Set the number of relaxation sweeps to perform.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	3

6.3.3.5. Dd-Ilu Preconditioner

Scope: Cg Solver
Summary: Use a domain-decomposition ILU(k) preconditioner.

begin Dd-Ilu Preconditioner

   Fill Level {=} value

   Reordering {=} {off | on}

   Subdomain Overlap Level {=} value

   Use Thread Parallel Implementation {=} {off | on}

end Dd-Ilu Preconditioner

6.3.3.5.1. Line Commands

Fill Level

Syntax: Fill Level {=} value
Summary: Set the level of fill, k, for ILU(k).

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	0

Reordering

Syntax: Reordering {=} {off | on}
Summary: Determine whether or not to apply an RCM reordering.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	{off \| on}	ON

Subdomain Overlap Level

Syntax: Subdomain Overlap Level {=} value
Summary: Set the level of subdomain overlap used in constructing the preconditioner.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	0

Use Thread Parallel Implementation

Syntax: Use Thread Parallel Implementation {=} {off | on}
Summary: Control whether or not to use the thread parallel ILU implementation from Kokkos-Kernels.
Description: This will default to the appropriate value based on the platform Aria is built for, but in rare cases it may be helpful to disable the thread parallel implementation in a GPU build for debugging purposes.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	{off \| on}	ON

6.3.3.6. Dd-Ilut Preconditioner

Scope: Cg Solver
Summary: Use a domain-decomposition ILUT preconditioner.

begin Dd-Ilut Preconditioner

   Drop Tolerance {=} value

   Fill Fraction {=} value

   Reordering {=} {off | on}

   Subdomain Overlap Level {=} value

end Dd-Ilut Preconditioner

6.3.3.6.1. Line Commands

Drop Tolerance

Syntax: Drop Tolerance {=} value
Summary: Set the drop tolerance for ilut.
Description: Off-diagonal entries of the incomplete factorization smaller than the specified tolerance will be dropped.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	real	0

Fill Fraction

Syntax: Fill Fraction {=} value
Summary: Set the fill fraction for ilut.
Description: This parameter controls the number of nonzero entries that are kept in each row of the incomplete factorization. Larger values will use more memory and runtime, but may result in a more effective preconditioner.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	real	1

Reordering

Syntax: Reordering {=} {off | on}
Summary: Determine whether or not to apply an RCM reordering.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	{off \| on}	ON

Subdomain Overlap Level

Syntax: Subdomain Overlap Level {=} value
Summary: Set the level of subdomain overlap used in constructing the preconditioner.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	0

6.3.3.7. Dd-Parilut Preconditioner

Scope: Cg Solver
Summary: Use a domain-decomposition ParILUT preconditioner.
Description: ParILUT is similar to ILUT, but uses an iterative approach to compute the approximate L and U factors in order to enable fine grained parallelism that can improve performance on GPUs.

begin Dd-Parilut Preconditioner

   Fill Fraction {=} value

   Maximum Iterations {=} value

   Reordering {=} {off | on}

   Subdomain Overlap Level {=} value

end Dd-Parilut Preconditioner

6.3.3.7.1. Line Commands

Fill Fraction

Syntax: Fill Fraction {=} value
Summary: Set the fill level for par_ilut.
Description: This parameter controls the number of nonzero entries that are kept in each row of the incomplete factorization. Larger values will use more memory and runtime, but may result in a more effective preconditioner.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	real	1

Maximum Iterations

Syntax: Maximum Iterations {=} value
Summary: Set the maximum number of iterations of the par_ilut algorithm.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	5

Reordering

Syntax: Reordering {=} {off | on}
Summary: Determine whether or not to apply an RCM reordering.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	{off \| on}	ON

Subdomain Overlap Level

Syntax: Subdomain Overlap Level {=} value
Summary: Set the level of subdomain overlap used in constructing the preconditioner.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	0

6.3.3.8. Fastilu Preconditioner

Scope: Cg Solver
Summary: Use a domain-decomposition FastILU(k) preconditioner.
Description: FastILU is a beta preconditioner that uses an iterative approximation to the standard DD-ILU preconditioner in order to expose more parallelism for potentially better performance on GPUs.

begin Fastilu Preconditioner

   Damping Factor {=} value

   Fill Level {=} value

   Reordering {=} {off | on}

   Subdomain Overlap Level {=} value

   Sweeps {=} value

   Triangular Solver Type {=} {fast | standard}

end Fastilu Preconditioner

6.3.3.8.1. Line Commands

Damping Factor

Syntax: Damping Factor {=} value
Summary: Set the damping factor for the FastILU algorithm.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	real	0.2

Fill Level

Syntax: Fill Level {=} value
Summary: Set the level of fill, k, for FastILU(k).

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	0

Reordering

Syntax: Reordering {=} {off | on}
Summary: Determine whether or not to apply an RCM reordering.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	{off \| on}	ON

Subdomain Overlap Level

Syntax: Subdomain Overlap Level {=} value
Summary: Set the level of subdomain overlap used in constructing the preconditioner.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	0

Sweeps

Syntax: Sweeps {=} value
Summary: Set the number of sweeps for iteratively computing the ILU approximation via the FastILU algorithm.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	integer	5

Triangular Solver Type

Syntax: Triangular Solver Type {=} {fast | standard}
Summary: Set the triangular solver type for FastILU

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	{fast \| standard}	Fast

6.3.3.9. Expert Ifpack2 Preconditioner

Scope: Cg Solver
Summary: Use an Ifpack2 preconditioner with parameters specified in an XML file.

begin Expert Ifpack2 Preconditioner

   Xml File {=} value

end Expert Ifpack2 Preconditioner

6.3.3.9.1. Line Commands

Xml File

Syntax: Xml File {=} value
Summary: Supply the name of an XML file containing an Ifpack2 parameter list.
Description: The supplied XML file must contain a ParameterList with a “preconditioner type:” string parameter corresponding to the desired type of Ifpack2 preconditioner as well as any additional parameters for that preconditioner.

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	string	–

6.3.3.10. Expert Teko Preconditioner

Scope: Cg Solver
Summary: Use a teko preconditioner with parameters specified in an XML file.

begin Expert Teko Preconditioner

   Define Matrix Subblock Number = number Dof = dof name

   Inverse Method {=} value

   Xml File {=} value

end Expert Teko Preconditioner

6.3.3.10.1. Line Commands

Define Matrix Subblock

Syntax: Define Matrix Subblock Number = number Dof = dof name
Summary: Define the dof associated with a matrix subblock for block preconditioning.
Description: Define the matrix subblock number and the equation to apply to that subblock. Please see https://trilinos.github.io/teko.html for more details

Parameter	Value	Default
number	integer	–
dof name	string	–

Inverse Method

Syntax: Inverse Method {=} value
Summary: Supply the name of the inverse method.
Description: The name of the inverse method must correspond to the name of a parameter list specified in the teko XML file. Please see https://trilinos.github.io/teko.html for more details

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	string	–

Xml File

Syntax: Xml File {=} value
Summary: Supply the name of an XML file containing a teko parameter list.
Description: The supplied XML file must contain a ParameterList with a valid teko parameter list. Please see https://trilinos.github.io/teko.html for more details

Parameter	Value	Default
{=}	{= \| are \| is}	–
value	string	–