program expression_equivalence
!
! simple evaluation of x*x-y*y
! when x and y are similar
!
! we will evaluate in three ways.
!
implicit none
real :: x = 1.002
real :: y = 1.001
real :: t1, t2, t3, t4, t5
   t1 = x-y
   t2 = x + y
   print *,t1
   print *,t2
   t3 = t1*t2
   t4 = x**2-y**2
   t5 = x*x-y*y
   print *,t3
   print *,t4
   print *,t5
end program expression_equivalence