text: /* -*- 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.
  ------------------------------------------------------------------------- */
  
  #ifdef FIX_CLASS
  
  FixStyle(addforce,FixAddForce)
  
  #else
  
  #ifndef LMP_FIX_ADDFORCE_H
  #define LMP_FIX_ADDFORCE_H
  
  #include "fix.h"
  
  namespace LAMMPS_NS {
  
  class FixAddForce : public Fix {
   public:
    FixAddForce(class LAMMPS *, int, char **);
    ~FixAddForce();
    int setmask();
    void init();
    void setup(int);
    void min_setup(int);
    void post_force(int);
    void post_force_respa(int, int, int);
    void min_post_force(int);
    double compute_scalar();
    double compute_vector(int);
    double memory_usage();
  
   private:
    double xvalue,yvalue,zvalue;
    int varflag,iregion;
    char *xstr,*ystr,*zstr,*estr;
    char *idregion;
    int xvar,yvar,zvar,evar,xstyle,ystyle,zstyle,estyle;
    double foriginal[4],foriginal_all[4];
    int force_flag;
    int ilevel_respa;
  
    int maxatom;
    double **sforce;
  };
  
  }
  
  #endif
  #endif
  
  /* ERROR/WARNING messages:
  
  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.
  
  E: Region ID for fix addforce does not exist
  
  Self-explanatory.
  
  E: Variable name for fix addforce does not exist
  
  Self-explanatory.
  
  E: Variable for fix addforce is invalid style
  
  Self-explanatory.
  
  E: Cannot use variable energy with constant force in fix addforce
  
  This is because for constant force, LAMMPS can compute the change
  in energy directly.
  
  E: Must use variable energy with fix addforce
  
  Must define an energy vartiable when applyting a dynamic
  force during minimization.
  
  */
  