c     file name : ex0201.f
      program newton
      parameter( imax=10, delta=1e-3 )
      f(x) = x**3 - 1d0
      ff(x) = 3*x**2
      write(*,*) 'Enter a primary value of x '
      read(*,*) x1
      y1=f(x1)
      write(*,*) 0, x1, y1
      do i=1,imax,1
        x2 = __ - _____/______
        y2 = _____
        write(*,*) i, x2, y2
        if( _______ .le. delta ) stop
        x1 = x2
      enddo
      end