SUBROUTINE AION(SI,SO,LEM,LEN)
      implicit none
C     ****
C     ****     CALCULATES INTEGRATED F(X) NEEDED FOR TOTAL AURORAL
C     ****     IONIZATION
C     ****
C     ****     SI = X, F(X) RETURNED IN SO
C     ****     LEN = ARRAY LENGTH
C     ****
! Args:
!     DIMENSION SI(1),SO(1),C(8)
      integer,intent(in) :: lem,len
      real,intent(in)  :: si(len)
      real,intent(out) :: so(len)
!
! Local:
      integer :: i
!
!     ****     CONSTANTS FOR PARAMETERIZATION (ED HSU)
!
      real :: c(8) =
     |  (/3.2333134511131,  2.5658873458085, 2.2540957232641,
     |    0.72971983372673, 1.1069072431948, 1.7134937681128,
     |    1.8835442312993,  0.86472135072090/)
!
!     DATA C/3.2333134511131,2.5658873458085,2.2540957232641,
!    10.72971983372673,1.1069072431948,1.7134937681128,
!    21.8835442312993,0.86472135072090/
!
      DO 2 I=LEM,LEN
        SO(I)=C(1)*SI(I)**C(2)*EXP(-C(3)*SI(I)**C(4))+
     |    C(5)*SI(I)**C(6)*EXP(-C(7)*SI(I)**C(8))
    2 CONTINUE
      RETURN
      END
C