amrex::HypreMLNodeLap Class Reference

Composite multi-level solve of an MLNodeLaplacian with hypre. More...

#include <AMReX_HypreMLNodeLap.H>

Public Types
using	BigInt = HYPRE_BigInt

Public Member Functions
	HypreMLNodeLap (MLNodeLaplacian const &a_linop, std::string a_prefix="hypre_mlnodelap", int a_verbose=0)
	Assemble the composite matrix from a prepared linear operator.
	~HypreMLNodeLap ()
	HypreMLNodeLap (HypreMLNodeLap const &)=delete
	HypreMLNodeLap (HypreMLNodeLap &&)=delete
HypreMLNodeLap &	operator= (HypreMLNodeLap const &)=delete
HypreMLNodeLap &	operator= (HypreMLNodeLap &&)=delete
void	solve (Vector< MultiFab * > const &a_sol, Vector< MultiFab const * > const &a_rhs, Real a_reltol, Real a_abstol, int a_maxiter)
	Solve the composite system.
void	setThrowException (bool t) noexcept
int	getNumIters () const
	Iterations and final relative residual of the last solve.
Real	getFinalResidualNorm () const
BigInt	numUnknowns () const
	Number of composite unknowns.
void	buildMatrix ()
	Internal: called by the constructor (public only for CUDA extended lambdas).

Detailed Description

Composite multi-level solve of an MLNodeLaplacian with hypre.

The composite operator of MLMG + MLNodeLaplacian is (up to a lumped-mass row scaling and extra fine-equation terms in the coarse/fine rows) the bilinear/trilinear finite-element operator with hanging-node constraints. This class assembles the symmetric form S = Q^T K Q, where K sums the Q1 element matrices of all cells not covered by a finer level and Q maps coarse/fine fine-level nodes to the coarse unknowns by multilinear interpolation. The right-hand side is transformed so that the solution equals MLMG's composite solution (up to a constant for singular problems, which are made consistent with nodal-volume weights; with an inconsistent composite right-hand side this differs slightly from MLMG's correction).

Supports the Sigma coarsening strategy with scalar, constant or mapped (per-direction) sigma, Cartesian coordinates, and refinement ratios 2 and 4; and, in EB builds, the RAP strategy with embedded boundaries, where the element matrices of cut cells are integrated over their fluid part (MLNodeLaplacian's EB integrals), covered cells are skipped, and nodes without fluid are not unknowns. At coarse/fine nodes next to cut cells this composite operator is the consistent finite-element one, whereas MLMG's reflux treats the cells there as regular.

The solver is configured with the HypreIJIface keys under the given ParmParse prefix (default "hypre_mlnodelap"). Further keys:

• <prefix>.backend = hypre | algmg (default hypre): solve the assembled system with hypre or with AMReX's AlgMG, configured by <prefix>.algmg.* (see composite::algmg_parse_options).
• <prefix>.dump_matrix = N (default 0): write the systems of the first N solves with this dump prefix (counted over all objects of the run) in Matrix Market format for external analysis: for solve k, <dump_prefix>_<k>_A.mtx, _b.mtx, _x.mtx (matrix, right-hand side, solution) and _rows.txt (per row: level, node index, scaling). The dumped system is the one solved, S' x' = b' with S' = s S s, b' = s b, x = s x'. <prefix>.dump_prefix defaults to the ParmParse prefix. Files with more than <prefix>.dump_gather_max values (matrix entries, or vector and row-map values; default 5e7) are written one per rank, as <file>.<rank>.
• <prefix>.eb_scaling (default 1): in EB builds, scale the unknowns by 1/sqrt(nodal fluid fraction) so that rows next to small cut cells count in the residual norm.

Member Typedef Documentation

BigInt

using amrex::HypreMLNodeLap::BigInt = HYPRE_BigInt

Constructor & Destructor Documentation

HypreMLNodeLap() [1/3]

amrex::HypreMLNodeLap::HypreMLNodeLap	(	MLNodeLaplacian const &	a_linop,
		std::string	a_prefix = "hypre_mlnodelap",
		int	a_verbose = 0 )

Assemble the composite matrix from a prepared linear operator.

Parameters

a_linop	MLNodeLaplacian with sigma set and masks built (e.g. after an MLMG solve or MLMG::prepareForSolve).
a_prefix	ParmParse prefix for the hypre solver options.
a_verbose	Verbosity.

~HypreMLNodeLap()

amrex::HypreMLNodeLap::~HypreMLNodeLap ( )

default

HypreMLNodeLap() [2/3]

amrex::HypreMLNodeLap::HypreMLNodeLap ( HypreMLNodeLap const & )

delete

HypreMLNodeLap() [3/3]

amrex::HypreMLNodeLap::HypreMLNodeLap ( HypreMLNodeLap && )

delete

Member Function Documentation

buildMatrix()

void amrex::HypreMLNodeLap::buildMatrix

(

)

Internal: called by the constructor (public only for CUDA extended lambdas).

getFinalResidualNorm()

Real amrex::HypreMLNodeLap::getFinalResidualNorm ( ) const

inlinenodiscard

getNumIters()

int amrex::HypreMLNodeLap::getNumIters ( ) const

inlinenodiscard

Iterations and final relative residual of the last solve.

numUnknowns()

BigInt amrex::HypreMLNodeLap::numUnknowns ( ) const

inlinenodiscard

Number of composite unknowns.

operator=() [1/2]

HypreMLNodeLap & amrex::HypreMLNodeLap::operator= ( HypreMLNodeLap && )

delete

operator=() [2/2]

HypreMLNodeLap & amrex::HypreMLNodeLap::operator= ( HypreMLNodeLap const & )

delete

setThrowException()

void amrex::HypreMLNodeLap::setThrowException ( bool t )

inlinenoexcept

Throw std::runtime_error instead of aborting when the solve fails (no convergence, a hypre error, a non-finite residual, AlgMG diverging)

solve()

void amrex::HypreMLNodeLap::solve	(	Vector< MultiFab * > const &	a_sol,
		Vector< MultiFab const * > const &	a_rhs,
		Real	a_reltol,
		Real	a_abstol,
		int	a_maxiter )

Solve the composite system.

Parameters

a_sol	Per-level nodal solution. On input, its values on Dirichlet domain boundaries are the boundary values (as with MLMG); on output it is filled everywhere, including covered and coarse/fine nodes, like MLMG.
a_rhs	Per-level nodal right-hand side as produced by MLNodeLaplacian::compRHS (MLMG's composite RHS).
a_reltol	Relative tolerance.
a_abstol	Absolute tolerance (<= 0: unused).
a_maxiter	Iteration limit.

---

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

• /home/runner/work/amrex/amrex/Src/Extern/HYPRE/AMReX_HypreMLNodeLap.H
• /home/runner/work/amrex/amrex/Src/Extern/HYPRE/AMReX_HypreMLNodeLap.cpp