module data

 implicit none
 save

 type coord
     real*8   :: x,y,z
 end type coord

end module data

program example2

 use data

 implicit none

 type (coord)   :: p1,p2

 real*8         :: d


 p1%x=1.d0
 p1%y=2.d0
 p1%z=0.d0

 p2%x=3.d0
 p2%y=0.d0
 p2%z=1.d0

 call sub(p1,p2,d)

 write(*,*) 'Distance between points p1 and p2 is', d

 stop

end program example2      


subroutine sub(p1,p2,d)

 use data

 implicit none

 type (coord), intent(in)  :: p1,p2
 real*8      , intent(out) :: d

 d=dsqrt( (p1%x - p2%x)**2 + (p1%y - p2%y)**2 + (p1%z - p2%z)**2 )

 return

end subroutine sub