SUBROUTINE hermit_ex ( y, n, h, expfac )
!-----------------------------------------------------------------------
! This routine was written by G. A. Parker
! If you find an error or have an improvement please send a messge to
! parker@phyast.nhn.uoknor.edu 
!-----------------------------------------------------------------------
!
!--------------------- hermit ------------------------------------------
!
! >>> hermit -- computes hermite polynomials
!
! --- on input the user supplies --
!
!     y  -- the dimensionless argument of the hermite polynomial
!     n  -- the order of the polynomial (n=0 ==> h0=1)
!
! --- on exit the routine returns --
!
!     h  -- vector of length m, containing h(0)=h0 h(1)=h1, etc.
!
!----------------------------------------------------------------------
!
IMPLICIT REAL*8 ( a - h, o - z )
DIMENSION h(0:n+1)
!
!------------------- execution begins here ----------------------------
!
h(0) = 1.0d0*expfac
IF( n .eq. 0 ) RETURN
!
ty = 2.0d0*y
h(1) = ty*expfac
IF( n .eq. 1 ) RETURN
!
tn = 0.0d0
!
DO i  = 1, n-1, 2
   tn    = tn + 2.0d0
   h(i+1) = -y*h(i)/(i+1) + i*h(i-1)/(i+1)
   h(i+2) =  ty*h(i+1) + h(i)
ENDDO
!
RETURN
END