subroutine MeanSD( n, x, mean, sd )
!
!     Return the mean and standard deviation of the array x
!
!     B. Knapp, 1999-08-19
!
      implicit none
!
!     Input
      integer n
      real*8 x(n)
!
!     Output
      real*8 mean, sd
!
!     Local
      integer j
      real*8 sumx, sumx2
!
      sumx = 0.d0
      sumx2 = 0.d0
      do j=1,n
         sumx = sumx + x(j)
         sumx2 = sumx2 + x(j)**2
      enddo
!
      mean = sumx/n
      if ( n .gt. 1 ) then
         sd = sqrt( max( 0.d0, sumx2-sumx**2/n )/(n-1) )
      else
         sd = 0.d0
      endif
!
      return
      end