anchor.diff:    101 i = i + 1
         if (i.gt.narg) goto 102
             call getarg(i,tag)
  -          if (tag(1:2).eq.'-n') then
  +          if (tag(1:5).eq.'-seed') then
  +              i = i + 1
  +              call getarg(i,tag)
  +              read(tag,*) seed
  +          elseif (tag(1:2).eq.'-n') then
                 i = i + 1
                 call getarg(i,tag)
                 read(tag,*) nvar
  
positive.code: C----
        IMPLICIT none
        CHARACTER*80 ifile,ofile
        INTEGER i,nvar,input,output,idum
        REAL*8 val(10),dval(10)
        EXTERNAL ran2
        REAL ran2,random
  
  C Parse command line
        call gcmdln(ifile,ofile,nvar)
        if (ifile.eq.'stdin') then
            input = 5
        else
  
negative.code: 
  C Initialize random number generator
        call raninit(idum)
        if (seed.gt.0) idum = -seed
  
  C Perturb input data
    101 read(input,*,end=102) (val(i),i=1,nvar),(dval(i),i=1,nvar)
  