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#ifndef LINEAR_SOLVER_H
#define LINEAR_SOLVER_H
// ATC includes
#include "ATC_TypeDefs.h"
#include "MatrixLibrary.h"
#include "ATC_Error.h"
// other includes
#include <set>
#include <map>
#include "LammpsInterface.h"
#include "CG.h"
#include "GMRES.h"
namespace ATC {
/**
* @class LinearSolver
* @brief a class to solve a system of linear equations
* A x = b subject to a set of constraints { x_i = y_i }
*/
class LinearSolver {
public:
enum LinearSolveType {
AUTO_SOLVE=-1,
DIRECT_SOLVE=0,
ITERATIVE_SOLVE,
ITERATIVE_SOLVE_SYMMETRIC
};
enum LinearSolveConstraintHandlingType {
AUTO_HANDLE_CONSTRAINTS=-1,
NO_CONSTRAINTS=0,
CONDENSE_CONSTRAINTS,
PENALIZE_CONSTRAINTS
};
/** Constructor */
LinearSolver( // does not assume that A is persistent
const SPAR_MAT & A, // lhs matrix "deep" copy
const BC_SET & bcs, // constraints
const int solverType = AUTO_SOLVE,
const int bcHandlerType = -1,
bool parallel = false
);
LinearSolver( // assumes A is persistent
const SPAR_MAT & A, // lhs matrix "shallow" copy
const int solverType = AUTO_SOLVE,
bool parallel = false
);
/** Destructor */
virtual ~LinearSolver() {};
/** (re)initialize
- if bcs are provided the lhs matrix is re-configured
for the new constraints
- if the class is to be reused with new constraints
allow_reinitialization must be called before first solve, etc */
void allow_reinitialization(void); // depending on method save a copy of A
void set_homogeneous_bcs(void) { homogeneousBCs_ = true;} // for nonlinear solver, solve for increment
void initialize(const BC_SET * bcs = nullptr);
/** solve
- solves A x = b
- if a "b" is provided it is used as the new rhs */
bool solve(VECTOR & x, const VECTOR & b);
/** greens function
- returns the solution to a Kronecker delta rhs b = {0 0 .. 1 .. 0 0}
and with homogeneous constraints {x_i = 0} */
void greens_function(int I, VECTOR & G_I);
/** eigensystem
- returns the e-values & e-vectors for constrained system Ax + v x = 0
- if M is provided the eval problem : ( A + v M ) x = 0 is solved*/
void eigen_system(DENS_MAT & eigenvalues, DENS_MAT & eigenvectors,
const DENS_MAT * M = nullptr);
/** access to penalty coefficient
- if a penalty method is not being used this returns zero */
double penalty_coefficient(void) const {return penalty_;};
/** change iterative solver parameters */
void set_max_iterations(const int maxIter) {
if (solverType_ != ITERATIVE_SOLVE && solverType_ != ITERATIVE_SOLVE_SYMMETRIC ) throw ATC_Error("inappropriate parameter set in LinearSolver");
maxIterations_=maxIter;
}
void set_tolerance(const double tol) { tol_=tol;}
/* access to number of unknowns */
int num_unknowns(void) const
{
int nUnknowns = nVariables_;
if (bcs_) { nUnknowns -= bcs_->size(); }
return nUnknowns;
}
protected:
/** flavors */
int solverType_;
int constraintHandlerType_ ;
/** number of variables = number of rows of matrix */
int nVariables_;
/** initialize methods */
bool initialized_,initializedMatrix_,initializedInverse_;
bool matrixModified_,allowReinitialization_;
bool homogeneousBCs_;
void setup(void);
void initialize_matrix(void);
void initialize_inverse(void);
void initialize_rhs(void);
/** constraint handling methods to modify the RHS */
void add_matrix_penalty(void); /** penalty */
void partition_matrix(void); /** condense */
/** constraint handling methods to modify the RHS */
void add_rhs_penalty(void); /** penalty */
void add_rhs_influence(void); /** condense */
/** set fixed values */
void set_fixed_values(VECTOR & x);
/** constraints container */
const BC_SET * bcs_;
/** rhs vector/s */
const VECTOR * rhs_;
DENS_VEC rhsDense_; // modified
const VECTOR * b_; // points to appropriate rhs
/** lhs matrix */
const SPAR_MAT & matrix_;
SPAR_MAT matrixCopy_; // a copy that will be modified by penalty methods
SPAR_MAT matrixOriginal_; // a copy that is used for re-initialization
const SPAR_MAT * matrixSparse_; // points to matrix_ or matrixCopy_
DENS_MAT matrixDense_; // a dense copy for lapack
/** partitioned matrix - condense constraints */
DENS_MAT matrixFreeFree_, matrixFreeFixed_;
/** maps for free and fixed variables for partitioned matrix - condense */
std::set<int> freeSet_, fixedSet_;
std::map<int,int> freeGlobalToCondensedMap_;
/** inverse matrix matrix - direct solve */
DENS_MAT matrixInverse_;
/** pre-conditioner diagonal of the matrix - iterative solve */
DIAG_MAT matrixDiagonal_;
/** penalty coefficient - penalty constraints */
double penalty_;
/** max iterations - iterative solve */
int maxIterations_;
/** max restarts - GMRES solve */
int maxRestarts_;
/** tolerance - iterative solve */
double tol_;
/** run solve in parallel */
bool parallel_;
};
} // namespace ATC
#endif
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