program c7p2
      implicit none
      real x(3),y(3),z(3)
 
      x(1) = 1
      x(2) = 0
      x(3) = 0
      y(1) = 0
      y(2) = 1
      y(3) = 0
      call cross(x,y,z)
      print *, z(1)
      print *, z(2)
      print *, z(3)
      end

      subroutine cross(x,y,z)
      real x(3),y(3),z(3)
      z(1) = x(2)*y(3)-x(3)*y(2)
      z(2) = x(3)*y(1)-x(1)*y(3)
      z(3) = x(1)*y(2)-x(2)*y(1)

      return 
      end