Calculate natural logarithm

natlog.for

c
c evaluate the natural logarithm e
c 
c variables
c   123456  a
c   fln     the value of the natural logarithm
c   iterm   the current term in the summation
c   next    the next number in a factorial operation
c   fdenom  the value of the current factorial
c
c234567
      fln = 1
      iterm = 1
10    if (iterm .lt. 15) goto 20
      goto 30
20    next = iterm - 1
      fdenom = iterm
50    if (next .le. 1) goto 40
      fdenom = fdenom * next * 1.
      next = next - 1
      goto 50
40    fln = fln + (1. / fdenom)
      write (6, 70) iterm, fdenom, fln
70    format ('TERM: ', I2, '  DENOM: ', F15.0, '  ln so far: ', F20.8)
      iterm = iterm + 1
      goto 10
30    write (6, 60) fln
60    format ('THE VALUE OF THE NATURAL LOGARITHM (LN) IS ', F20.8)
      stop
      end