EPSILON — Epsilon function ¶EPSILON(X) returns the smallest number E of the same kind
as X such that 1 + E > 1.
Fortran 90 and later
Inquiry function
RESULT = EPSILON(X)
| X | The type shall be REAL. | 
The return value is of same type as the argument.
program test_epsilon
    real :: x = 3.143
    real(8) :: y = 2.33
    print *, EPSILON(x)
    print *, EPSILON(y)
end program test_epsilon