Sparse linear solver parameters

The sparselinsolverparams field has the following general syntax:

	[lstype$^M$(in) #]
	[smtype(in) #]
	solverParams$^M$(string) #

where parameter lstype allows to select solver for linear system of equations. Currently supported values are 0 (default) for direct solver (ST_Direct), 1 for Iterative Method Library (IML) solver (ST_IML), 2 for Spooles direct solver, 3 for Petsc library family of solvers, and 4 for DirectSparseSolver (ST_DSS). Parameter smtype allows to select sparse matrix storage scheme. The scheme should be compatible with solver type. Currently supported values (marked as ``id'') are summarized in table (1). The 0 value is default and selects the symmetric skyline (SMT_Skyline). Ther possible storage formats include unsymmetric skyline (SMT_SkylineU), compressed column (SMT_CompCol), dynamically growing compressed column (SMT_DynCompCol), symmetric compressed column (SMT_SymCompCol), spooles library storage format (SMT_SpoolesMtrx), PETSc library matrix representation (SMT_PetscMtrx, a sparse serial/parallel matrix in AIJ format), and DSS compatible matrix representations (SMT_DSS_*). The allowed lstype and smtype combinations are summarized in the table (1), together with solver parameters related to specific solver.

Table 1: Solver and stoorage scheme compatibility.

Storage format	id	Sparse solver
		Direct	IML	Spooles	Petsc	DSS
SMT_Skyline	0	+	+
SMT_SkylineU	1	+	+
SMT_CompCol	2		+
SMT_DynCompCol	3		+
SMT_SymCompCol	4		+
SMT_DynCompRow	5		+
SMT_SpoolesMtrx	6			+
SMT_PetscMtrx	7				+
SMT_DSS_sym_LDL	8					+
SMT_DSS_sym_LL	9					+
SMT_DSS_unsym_LU	10					+

The solver parameters in solverParams depend on the solver type and are summarized in table (2).

Table 2: Solver parameters.

Solver type	id	Solver parameters
ST_Direct	0
ST_IML	1	[stype(in) #] lstol(rn) # lsiter(in) #lsprecond(in) #
		[precondattributes(string) #]
ST_Spooles	2	[msglvl(in) #] [msgfile(s) #]
ST_Petsc	3	see Petsc manual, for details2
ST_DSS	4

The stype allows to select particular iterative solver from IML library, currently supported values are 0 (default) for Conjugate-Gradient solver, 1 for GMRES solver. Parameter lstol represents the maximum value of residual after the final iteration and the lsiter is maximum number of iteration for iterative solver. The precondattributes parameters contains the optional preconditioner parameters. The lsprecond parameter determines the type of preconditioner to be used. The possible values of lsprecond together with supported storage schemes and their descriptions are summarized in table (3).

Table 3: Preconditioning summary.

Precond type	id	Compatible storage	Description and parameters
IML_VoidPrec	0	all	No preconditioning
IML_DiagPrec	1	all	Diagonal preconditioning
IML_ILUPrec	2	SMT_CompCol	Incoplete LU Decomposition
		SMT_DynCompCol	with no fill up
IML_ILUPrec	3	SMT_DynCompRow	Incoplete LU (ILUT) with
			fillup.
			The precondattributes are:
			[droptol(rn) #] [partfill(in) #].
			droptol dropping tolerance
			partfill level of fill-up
IML_ICPrec	4	SMT_SymCompCol	Incoplete Cholesky
		SMT_CompCol	with no fill up