PROGRAM main
    IMPLICIT NONE
    REAL :: X

    X = diff(1.23, 4.56)
    PRINT *, X
    X = diff(-7.89, 3.42)
    PRINT *, X
    X = diff(4.29, -0.98)
    PRINT *, X

CONTAINS

    ELEMENTAL FUNCTION diff (A, B)
        IMPLICIT NONE
        REAL :: diff
        REAL, INTENT(IN) :: A, B
        diff = A-B
    END FUNCTION diff

END PROGRAM main