PROGRAM main
    IMPLICIT NONE
    REAL :: X

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