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solver_cg.hh
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/**
* file solver_cg.hh
*
* @author Till Junge <till.junge@epfl.ch>
*
* @date 20 Dec 2017
*
* @brief class for a simple implementation of a conjugate gradient
* solver. This follows algorithm 5.2 in Nocedal's Numerical
* Optimization (p 112)
*
* @section LICENSE
*
* Copyright © 2017 Till Junge
*
* µSpectre is free software; you can redistribute it and/or
* modify it under the terms of the GNU 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 General Public License
* along with GNU Emacs; see the file COPYING. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifndef SOLVER_CG_H
#define SOLVER_CG_H
#include "solver/solver_base.hh"
#include "common/field.hh"
#include <functional>
namespace muSpectre {
template <Dim_t DimS, Dim_t DimM=DimS>
class SolverCG: public SolverBase<DimS, DimM>
{
public:
using Parent = SolverBase<DimS, DimM>;
using Ccoord = typename Parent::Ccoord;
using Tg_req_t = typename Parent::TangentRequirement;
// cg only needs to handle fields that look like strain and stress
using Field_t = TensorField<
typename Parent::Collection_t, Real, secondOrder, DimM>;
using Fun_t = std::function<void(const Field_t& in, Field_t & out)>;
constexpr static Tg_req_t tangent_requirement{Tg_req_t::NeedEffect};
//! Default constructor
SolverCG() = delete;
//! Constructor with domain resolutions, etc,
SolverCG(Ccoord resolutions, Real tol, Uint maxiter=0, bool verbose =false);
//! Copy constructor
SolverCG(const SolverCG &other) = delete;
//! 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;
//! actual solver
void solve(const Fun_t & tangent_effect,
const Field_t & rhs,
Field_t & x);
//! reset the iteration counter to zero
void reset_counter();
//! get the count of how many solve steps have been executed since
//! construction of most recent counter reset
Uint get_counter() const;
protected:
Tg_req_t get_tangent_req() const override final;
Field_t & r_k; // residual
Field_t & p_k; // search direction
Field_t & Ap_k; // effect of tangent on search direction
const Real tol;
const Uint maxiter;
const bool verbose;
Uint counter{};
private:
};
} // muSpectre
#endif /* SOLVER_CG_H */
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