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muSpectre/src/solver/solver_cg.hh
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solver_cg.hh
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/**
* file solver_cg.hh
*
* @author Till Junge <till.junge@epfl.ch>
*
* @date 24 Apr 2018
*
* @brief class fo a simple implementation of a conjugate gradient solver.
* This follows algorithm 5.2 in Nocedal's Numerical Optimization
* (p 112)
*
* Copyright © 2018 Till Junge
*
* µSpectre is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation, either version 3, or (at
* your option) any later version.
*
* µSpectre is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with µSpectre; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* * Boston, MA 02111-1307, USA.
*
* Additional permission under GNU GPL version 3 section 7
*
* If you modify this Program, or any covered work, by linking or combining it
* with proprietary FFT implementations or numerical libraries, containing parts
* covered by the terms of those libraries' licenses, the licensors of this
* Program grant you additional permission to convey the resulting work.
*/
#ifndef SOLVER_CG_H
#define SOLVER_CG_H
#include "solver/solver_base.hh"
namespace muSpectre {
/**
* implements the `muSpectre::SolverBase` interface using a
* conjugate gradient solver. This particular class is useful for
* trouble shooting, as it can be made very verbose, but for
* production runs, it is probably better to use
* `muSpectre::SolverCGEigen`.
*/
class SolverCG: public SolverBase
{
public:
using Parent = SolverBase; //!< standard short-hand for base class
//! for storage of fields
using Vector_t = Parent::Vector_t;
//! Input vector for solvers
using Vector_ref = Parent::Vector_ref;
//! Input vector for solvers
using ConstVector_ref = Parent::ConstVector_ref;
//! Output vector for solvers
using Vector_map = Parent::Vector_map;
//! Default constructor
SolverCG() = delete;
//! Copy constructor
SolverCG(const SolverCG &other) = delete;
/**
* Constructor takes a Cell, tolerance, max number of iterations
* and verbosity flag as input
*/
SolverCG(Cell & cell, Real tol, Uint maxiter, bool verbose=false);
//! Move constructor
SolverCG(SolverCG &&other) = default;
//! Destructor
virtual ~SolverCG() = default;
//! Copy assignment operator
SolverCG& operator=(const SolverCG &other) = delete;
//! Move assignment operator
SolverCG& operator=(SolverCG &&other) = default;
//! initialisation does not need to do anything in this case
void initialise() override final {};
//! returns the solver's name
std::string get_name() const override final {return "CG";}
//! the actual solver
Vector_map solve(const ConstVector_ref rhs) override final;
protected:
Vector_t r_k; //!< residual
Vector_t p_k; //!< search direction
Vector_t Ap_k; //!< directional stiffness
Vector_t x_k; //!< current solution
private:
};
} // muSpectre
#endif /* SOLVER_CG_H */
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