anchor.diff:       1 '-seed SEED  Start random numbers with integer SEED ',
        2                  '(useful for continuing chain of rands)'
         write(*,*)
  +     1 '-p          Print results to standard output'
  +      write(*,*)
        1 '-h          Online help'
         write(*,*)
         STOP
  
positive.code: 
  C======================================================================C
  
        SUBROUTINE gcmdln(ifile,ofile,nvar,seed)
        IMPLICIT NONE
        CHARACTER*80 ifile,ofile,tag
        INTEGER i,narg,nvar,seed
        ifile = 'none'
        ofile = 'none'
        seed = -1
        nvar = 1
        narg = iargc()
        if (narg.eq.0) call usage('')
        i = 0
  
negative.code:           write(*,*)
        endif
        write(*,*)
       1 'Usage: perturb -f IFILE -o OFILE -n NVAR [-seed SEED] [-p]'
        write(*,*)
        write(*,*)
       1 '-f IFILE    Input data file with uncertainties (v1..vn d1..dn)'
  