program test_newton
    use newton_root
    integer:: ierr
    real(DOUBLE):: x0,tol
!
!  Read the initial guess (x0) and convergence tolerance from the
!  standard input.
!
    read(5,*) x0,tol
!
!  Find the root and print the results.
!
    call newton(myfunc,myderiv,x0,tol,ierr)
    if(ierr.eq.0) then
       write(6,*) x0
    else
       write(6,*) 'no convergence'
    endif
    stop
    contains
!-----------
!  MYFUNC is the function whose root we seek.  This is just an example.
!
       function myfunc(x)
       real(DOUBLE):: myfunc
       real(DOUBLE),intent(in):: x
!
       myfunc=x**2-2.0   ! for finding sqrt(2)
       return
       end function myfunc
!-----------
!  MYDERIV is the derivative of function whose root we seek.
!  This is just an example.
!
       function myderiv(x)
       real(DOUBLE):: myderiv
       real(DOUBLE),intent(in):: x
!
       myderiv=2.0*x
       return
       end function myderiv
!-----------
    end program test_newton