NAME
solver_option - options for direct or interative solvers
DESCRIPTION
This class implements a set of options for direct or iterative solvers, as implemented by the solver(2). An instance of this class can be supplied to the solver constructor.
OPTIONS
iterative
Indicate if we want to use an iterative solver or a a direct one. Default is direct for 1D or 2D problems and iterative for 3D ones. Direct solver is mumps when available, otherwise umfpack or builtin solver when none of these solvers are available at Rheolef configure time. Iterative solver is cg for symmetric positive definite systems and gmres otherwise.
OPTIONS FOR ITERATIVE SOLVERS
|
tol |
Tolerance for the stopping criterion. Default is the machine epsilon for the default Float type. The default Float type is double defined at Rheolef configure time and is double by default, when no special configure option is used. |
max_iter
Maximum number of iteration when using iterative method.
absolute_stopping
Absolute or relative stopping criterion. With the absolute criterion, the algorithm stops when norm(A*x-b) < tol, otherwise it stops when norm(A*x-b) < tol*norm(b). Default is to use an absolute stopping criterion.
residue
On return, gives the obtained residue, optionally divided by the initial one when using a relatiive stopping. It is less or equal to tol when the iterative algorithm stops with succes.
|
n_iter |
On return, gives the number of iterations performed. It is always less or equal to max_iter when the iterative algorithm stops with succes. | ||
|
p_err |
A pointer to the odiststeam standard error where residues are printed during iterations. When this pointer is zero, no errors are printed. Default is to print to derr. | ||
|
label |
When printing errors, each line is prefixed by [@var{label]}. When the label is empty, each iterative algorithm uses its default label, e.g. "cg" for the conjugate gradient cg. By default the label is empty and this option is used to superset the algorithm default. |
krylov_dimension
The dimension of the Krylov space used by the gmres algorithm. Default is krylov_dimension=6.
OPTIONS FOR DIRECT SOLVERS
n_refinement
Number of iterative refinement, when using direct method (umfpack only support it). This option is only active when using iterative solvers.
compute_determinant
Compute also the determinant of the matrix. This option is only active when using direct solvers. Requires mumps or umfpack.
prefered_library
When both mumps and umfpack are available, then mumps is the default. This option allows one to force to choose umfpack, by setting the string to "umfpack". This option is only active when using direct solvers.
OPTIONS FOR DEVELOPPERS
verbose_level
Can be set to 0, 1, 2 or 3. The default is 0.
level_of_fill
Built an incomplete factorization with the prescribed level of fill [1:5].
do_check
Performs extra checks for debug.
force_seq
In distributed mode, restrict the linear system resolution to diagonal blocs per process. This option is only active when using the mumps direct solver.
|
ooc |
Out-of-core limit (Mo/percent depending on compilation options). In development. |
amalgamation
Level of amalgamation [10:70] for Kass. In development.
IMPLEMENTATION
class
solver_option {
public:
typedef std::size_t size_type;
static const long int decide = -1;
mutable long int iterative;
Float tol;
size_type max_iter;
bool absolute_stopping;
mutable Float residue;
mutable size_type n_iter;
odiststream* p_err;
mutable std::string label;
size_type krylov_dimension;
size_type n_refinement;
bool compute_determinant;
std::string prefered_library;
size_type verbose_level;
bool do_check;
bool force_seq;
size_type level_of_fill;
size_type amalgamation;
size_type ooc;
// allocator and default values:
solver_option()
: iterative (decide),
#if defined(_RHEOLEF_HAVE_FLOAT128)
tol (1e6*std::numeric_limits<Float>::epsilon()),
#else
tol (std::numeric_limits<Float>::epsilon()),
#endif
max_iter (100000),
absolute_stopping (true),
residue (0),
n_iter (0),
p_err (&derr),
label (),
krylov_dimension (6),
n_refinement (2),
compute_determinant(false),
prefered_library(),
verbose_level (0),
do_check (false),
force_seq (false),
level_of_fill (1),
amalgamation (10),
ooc (20000)
{
}
solver_option (const solver_option&);
solver_option& operator= (const solver_option&);
};
SEE ALSO
COPYRIGHT
Copyright (C) 2000-2018 Pierre Saramito <Pierre.Saramito [AT] imag.fr> GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>;. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.