opt_DCsrch.h

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#ifndef OPT_DCSRCH_H
#define OPT_DCSRCH_H
 
#include <iostream>
 
#include "constants.h"
 
namespace ModuleBase
{
 
class Opt_DCsrch
{
  public:
    Opt_DCsrch()
    {
        this->isave_ = new int[3];
        this->dsave_ = new double[14];
    }
    ~Opt_DCsrch()
    {
        delete[] this->isave_;
        delete[] this->dsave_;
    }
 
    //
    //
    //
    void set_paras(double ftol = 1e-4,
                   double gtol = 2e-1,
                   double xtol = 1e-12,
                   double stpmin = 0.,
                   double stpmax = ModuleBase::PI)
    {
        this->ftol_ = ftol;
        this->gtol_ = gtol;
        this->xtol_ = xtol;
        this->stpmin_ = stpmin;
        this->stpmax_ = stpmax;
    }
 
    void dcSrch(double& f, double& g, double& rstp, char* rtask);
 
  private:
    double ftol_ = 1e-4;  // nonnegative tolerance for the sufficient decrease condition.
    double gtol_ = 2e-1;  // nonnegative tolerance for the curvature condition.
    double xtol_ = 1e-12; // nonnegative relative tolerance for an acceptable step. The subroutine exits with a warning
                          // if the relative difference between sty and stx is less than xtol.
    double stpmin_ = 0.;  // nonnegative lower bound for the step.
    double stpmax_ = ModuleBase::PI; // nonnegative upper bound for the step.
    int* isave_ = nullptr;           // an integer work array of dimension 2.
    double* dsave_ = nullptr;        // a double precision work array of dimension 13.
};
} // namespace ModuleBase
 
#endif