implicit double precision (a-h,o-z)
      common x,y,sigmay,npts,mode,a,sigmaa,b,sigmab,r
      dimension x(100),y(100),sigmay(100)
1     type 100
      accept 101,npts
      if (npts) 999,999,2
2     type 102
      accept 101,mode
      type 103
      accept 101,nfile
      if (nfile) 50,10,10
10    type 104
      do 20 i=1,npts
20    accept 105,x(i),y(i),sigmay(i)
      goto 75
50    do 60 i=1,npts
60    read (21,105) x(i),y(i),sigmay(i)
75    call linfit
      type 200,b,sigmab
      type 201,a,sigmaa
      type 202,r
      type 203
      goto 1
999   stop
100   format(' number of points='$)
101   format(i)
102   format(' mode='$)
103   format(' file='$)
104   format('0input data:'/)
105   format(3d)
200   format(' slope     =',1pd20.6,'  (+/-)  ',1pd20.6)
201   format(' intercept =',1pd20.6,'  (+/-)  ',1pd20.6)
202   format('0correlation =',f15.8)
203   format('1')
      end