text: /* ----------------------------------------------------------------------
     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.
  ------------------------------------------------------------------------- */
  
  #include <mpi.h>
  #include <string.h>
  #include "compute_ke_rigid.h"
  #include "update.h"
  #include "force.h"
  #include "modify.h"
  #include "fix.h"
  #include "fix_rigid.h"
  #include "fix_rigid_small.h"
  #include "error.h"
  
  using namespace LAMMPS_NS;
  
  /* ---------------------------------------------------------------------- */
  
  ComputeKERigid::ComputeKERigid(LAMMPS *lmp, int narg, char **arg) :
    Compute(lmp, narg, arg), rfix(NULL)
  {
    if (narg != 4) error->all(FLERR,"Illegal compute ke/rigid command");
  
    scalar_flag = 1;
    extscalar = 1;
  
    int n = strlen(arg[3]) + 1;
    rfix = new char[n];
    strcpy(rfix,arg[3]);
  }
  
  /* ---------------------------------------------------------------------- */
  
  ComputeKERigid::~ComputeKERigid()
  {
    delete [] rfix;
  }
  
  /* ---------------------------------------------------------------------- */
  
  void ComputeKERigid::init()
  {
    irfix = modify->find_fix(rfix);
    if (irfix < 0) error->all(FLERR,"Fix ID for compute ke/rigid does not exist");
  
    if (strncmp(modify->fix[irfix]->style,"rigid",5))
      error->all(FLERR,"Compute ke/rigid with non-rigid fix-ID");
  }
  
  /* ---------------------------------------------------------------------- */
  
  double ComputeKERigid::compute_scalar()
  {
    invoked_scalar = update->ntimestep;
  
    if (strncmp(modify->fix[irfix]->style,"rigid",5) == 0) {
      if (strstr(modify->fix[irfix]->style,"/small")) {
        scalar = ((FixRigidSmall *) modify->fix[irfix])->extract_ke();
      } else scalar = ((FixRigid *) modify->fix[irfix])->extract_ke();
    }
    scalar *= force->mvv2e;
    return scalar;
  }
  