program zbrak_main

      integer n, nb_max, nb
      parameter (nb_max = 50)
      real fx, x1,x2,xb1(nb_max),xb2(nb_max)
      external fx
      
      write(*,*) 'What is the range (two numbers) to find roots ?'
      read (*,*) x1,x2

      write(*,*) 'How many internals to divide and check for roots ?'
      read (*,*) n

      write(*,*) 'Maximum number of  expected roots ? (no more than 50)'
      read (*,*) nb

      call zbrak(fx,x1,x2,n,xb1,xb2,nb)

      write(*,*) 'Answers and range of the roots found'
      do i=1,nb
        write(*,102) xb1(i), xb2(i)
      end do
 102  format (1x,'range is:',e12.3, '     and ', e12.3)

      end


      function fx(x)
      real fx,x
c     fx = x**3
      fx = 7*sin(x) + x
      end