anchor.diff:  real(c_double), parameter :: mass = 1.0
   real(c_double), parameter :: C6 = 4.0
   real(c_double), parameter :: C12 = 4.0
  +real(c_double), parameter :: cutoff = 3.0
  +real(c_double), parameter :: cutoffsq = cutoff*cutoff
   
   integer :: timesteps_read = 0
   
  +!interparticle distance
  +real(c_double), dimension(3) :: del
  +real(c_double) :: rsq
  +
   !intermediate variables
  -real(c_double) :: tcon_numerator = 0.0
  -real(c_double) :: tcon_denominator = 0.0
  -real(c_double) :: tconF = 0.0
  +real(c_double) :: tconF_numerator = 0.0
  +real(c_double) :: tconF_denominator = 0.0
   real(c_double) :: tcon1 = 0.0
   real(c_double) :: tkin = 0.0
  +real(c_double) :: tconF = 0.0
   
   !accumulators for averages over entire simulation
   real(c_double) :: tkin_ave = 0.0
  
positive.code: 
  !data to be read from the trajectory file
  integer(c_int) timestep, N
  real(c_double), dimension(3) :: box_lo, box_hi
  real(c_double), dimension(:,:), allocatable :: x, v, f
  logical(c_bool) :: loop_continue = .True.
  
  
negative.code: real(c_double) :: tconF_denominator_sq_ave = 0.0
  real(c_double) :: tcon1sq_ave = 0.0
  
  !error variables
  real(c_double) :: tkin_err = 0.0
  real(c_double) :: tconF_numerator_err = 0.0
  real(c_double) :: tconF_denominator_err = 0.0
  real(c_double) :: tconF_err = 0.0
  real(c_double) :: tcon1_err = 0.0
  
  call get_command_argument(1, filename, filename_len)
  
  file_opened = OpenFile(filename, filename_len)
  