anchor.diff:         end if
       end if
   
  +100 format(&
  +         'elss-sample (elss v0.2.1)                                                      '/& 
  +         '                                                                               '/&
  +         'Usage:                                                                         '/&
  +         '    elss-sample [options] -p <parameters_file>                                 '/&
  +         '    elss-learn [options] -c <checkpoint_file>                                  '/&
  +         '                                                                               '/&
  +         'Description:                                                                   '/&
  +         '    Simulate a trajectory in sequence space, using a model of pairwise         '/&
  +         '    interacting variables. The parameters of the model can either be read from '/&
  +         '    a file of parameters or from a checkpoint file generated by elss-learn.    '/&
  +         '                                                                               '/&
  +         'Required:                                                                      '/&
  +         '-p, --prm <prm_file>                                                           '/&
  +         '    Read the parameters of the model from file <prm_file>.                     '/&
  +         '                                                                               '/&
  +         '-c, --chk <chk_file>                                                           '/&
  +         '    Read the parameters of the model and the starting point for the simulation '/&
  +         '    from checkpoint file <chk_file>.                                           '/&
  +         '                                                                               '/&
  +         'Options:                                                                       '/&
  +         '-h, --help                                                                     '/&
  +         '    Display this help and exit.                                                '/&
  +         '                                                                               '/&
  +         '--prefix <str>                                                                 '/&         
  +         '    Prefix of output files.                                                    '/&
  +         '                                                                               '/&
  +         '-n, --nsweeps <n>, integer                                                     '/&
  +         '    Simulate <n> MC sweeps.                                                    '/&
  +         '    [default: 1000]                                                            '/&
  +         '                                                                               '/&
  +         '-u, --nupdate <n>, integer                                                     '/&
  +         '    Update model averages every <n> sweeps.                                    '/&
  +         '    [default: 10]                                                              '/&
  +         '                                                                               '/&
  +         '--seed <seed>, integer                                                         '/&
  +         '    Seed for initialization of pseudo-random number generator.                 '/&
  +         '    If == 0, the seed is computed from the system clock.                       '/&
  +         '    [default: 0]                                                               '/&
  +         '                                                                               '/&
  +         '-s, --seq <file>, string                                                       '/&
  +         '    Read the starting sequence from file <file>.                               '/&
  +         '    Overrides the starting sequence read in checkpoint file.                   '/&
  +         '    [default: generate random starting sequence]                               '/&
  +         '                                                                               '/&
  +         'Examples:                                                                      '/&
  +         '                                                                               '/)
  +
     end subroutine command_line_read
   
   end module sample_command_line
  
positive.code: 
      if (nargs == 0) then
         ! no args: print syntax and stop
         write(0,*) trim(syntax)
         error_code = 1
         return
      end if
  
negative.code:   implicit none
    private
    public :: command_line_read
  
  contains
  
    subroutine command_line_read(uprm,uchk,useq,rseed,beta,mc_nsweeps,nupdate,&
  