/* -*- c++ -*- ----------------------------------------------------------
   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
   http://lammps.sandia.gov, Sandia National Laboratories
   Steve Plimpton, sjplimp@sandia.gov

   Copyright (2003) Sandia Corporation.  Under the terms of Contract
   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
   certain rights in this software.  This software is distributed under
   the GNU General Public License.

   See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */

#ifndef LMP_MIN_H
#define LMP_MIN_H

#include "pointers.h"

namespace LAMMPS_NS {

class Min : protected Pointers {
 public:
  double einitial,efinal,eprevious;
  double fnorm2_init,fnorminf_init,fnorm2_final,fnorminf_final;
  double alpha_final;
  int niter,neval;
  int stop_condition;
  char *stopstr;
  int searchflag;     // 0 if damped dynamics, 1 if sub-cycles on local search

  Min(class LAMMPS *);
  virtual ~Min();
  virtual void init();
  virtual void setup(int flag=1);
  virtual void setup_minimal(int);
  virtual void run(int);
  void cleanup();
  int request(class Pair *, int, double);
  virtual bigint memory_usage() {return 0;}
  void modify_params(int, char **);
  virtual int modify_param(int, char **) {return 0;}
  virtual double fnorm_sqr();
  virtual double fnorm_inf();
  virtual double fnorm_max();

  enum{TWO,MAX,INF};

  // methods for spin minimizers
  double total_torque();
  double inf_torque();
  double max_torque();

  virtual void init_style() {}
  virtual void setup_style() = 0;
  virtual void reset_vectors() = 0;
  virtual int iterate(int) = 0;

  // possible return values of iterate() method
  enum{MAXITER,MAXEVAL,ETOL,FTOL,DOWNHILL,ZEROALPHA,ZEROFORCE,
       ZEROQUAD,TRSMALL,INTERROR,TIMEOUT,MAXVDOTF};

 protected:
  int eflag,vflag;            // flags for energy/virial computation
  int virial_style;           // compute virial explicitly or implicitly
  int external_force_clear;   // clear forces locally or externally

  double dmax;                  // max dist to move any atom in one step
  int linestyle;                // 0 = backtrack, 1 = quadratic, 2 = forcezero
                                // 3 = spin_cubic, 4 = spin_none

  int normstyle;                // TWO, MAX or INF flag for force norm evaluation

  double dtinit;              // store the default timestep

  // only for minimize style fire2
  int delaystep;              // minium steps of dynamics
  double dtgrow,dtshrink;     // timestep increase, decrease
  double alpha0,alphashrink;  // mixing velocities+forces coefficient
  double tmax,tmin;           // timestep multiplicators max, min
  int integrator;             // Newton integration: euler, leapfrog, verlet...
  int halfstepback_flag;      // half step backward when v.f <= 0.0
  int delaystep_start_flag;   // delay the initial dt_shrink
  int max_vdotf_negatif;      // maximum iteration with v.f > 0.0

  int nelist_global,nelist_atom;    // # of PE,virial computes to check
  int nvlist_global,nvlist_atom,ncvlist_atom;
  class Compute **elist_global;     // lists of PE,virial Computes
  class Compute **elist_atom;
  class Compute **vlist_global;
  class Compute **vlist_atom;
  class Compute **cvlist_atom;

  int triclinic;              // 0 if domain is orthog, 1 if triclinic
  int pairflag;
  int torqueflag,extraflag;

  int pair_compute_flag;            // 0 if pair->compute is skipped
  int kspace_compute_flag;          // 0 if kspace->compute is skipped

  int narray;                       // # of arrays stored by fix_minimize
  class FixMinimize *fix_minimize;  // fix that stores auxiliary data

  class Compute *pe_compute;        // compute for potential energy
  double ecurrent;                  // current potential energy

  bigint ndoftotal;           // total dof for entire problem

  int nvec;                   // local atomic dof = length of xvec
  double *xvec;               // variables for atomic dof, as 1d vector
  double *fvec;               // force vector for atomic dof, as 1d vector

  int nextra_global;          // # of extra global dof due to fixes
  double *fextra;             // force vector for extra global dof
                              // xextra is stored by fix

  int nextra_atom;            // # of extra per-atom variables
  double **xextra_atom;       // ptr to the variable
  double **fextra_atom;       // ptr to the force on the variable
  int *extra_peratom;         // # of values in variable, e.g. 3 in x
  int *extra_nlen;            // total local length of variable, e.g 3*nlocal
  double *extra_max;          // max allowed change per iter for atom's var
  class Pair **requestor;     // Pair that stores/manipulates the variable

  int kokkosable;             // 1 if this min style supports Kokkos

  int neigh_every,neigh_delay,neigh_dist_check;  // neighboring params

  virtual double energy_force(int);
  virtual void force_clear();

  void ev_setup();
  void ev_set(bigint);

  char *stopstrings(int);
};

}

#endif

/* ERROR/WARNING messages:

W: Using 'neigh_modify every 1 delay 0 check yes' setting during minimization

UNDOCUMENTED

E: Minimization could not find thermo_pe compute

This compute is created by the thermo command.  It must have been
explicitly deleted by a uncompute command.

E: Cannot use a damped dynamics min style with fix box/relax

This is a current restriction in LAMMPS.  Use another minimizer
style.

E: Cannot use a damped dynamics min style with per-atom DOF

This is a current restriction in LAMMPS.  Use another minimizer
style.

E: Cannot use hftn min style with fix box/relax

UNDOCUMENTED

E: Cannot use hftn min style with per-atom DOF

UNDOCUMENTED

E: Illegal ... command

Self-explanatory.  Check the input script syntax and compare to the
documentation for the command.  You can use -echo screen as a
command-line option when running LAMMPS to see the offending line.

U: Resetting reneighboring criteria during minimization

Minimization requires that neigh_modify settings be delay = 0, every =
1, check = yes.  Since these settings were not in place, LAMMPS
changed them and will restore them to their original values after the
minimization.

U: Energy due to X extra global DOFs will be included in minimizer energies

When using fixes like box/relax, the potential energy used by the minimizer
is augmented by an additional energy provided by the fix. Thus the printed
converged energy may be different from the total potential energy.

*/
