! internal.f90 - illustrate the use of internal subroutine
!                and the CONTAINS statement
!  This program requires that you input two real numbers, and it 
!   returns the square root of the sum of the squares.
! Compile this program using:
!   df internal.f90
!
program INTERNAL
   real a,b,c
   call find
   print *, "The square root of the sum of the squares of these two numbers is:", c
contains
   subroutine find
     write ( *,*) "input two real numbers:"
     read *, a,b
     c = sqrt(a**2 + b**2)
   end subroutine find
end