program smpl8
      real x,t,v1,v2
      integer, parameter :: n = 5
      real, dimension(n) :: diff
      integer i
  21  format(i4,' x=',f5.2,' tail=',f8.4)
  22  format(2f12.6)
      do i = 1,n
      x = real(i)
      t = func(x) ! logistic tail probs
      diff(i) = 1. - t
      write(6,21) i,x,t
      end do  ! loop on i
      call norms(diff,n,v1,v2)
      write(6,22) v1,v2
      stop
      end program smpl8
      real function func(z)   ! note dummy name 
      implicit none
      real, intent(in) ::  z  ! declares variable as input only
      func = 1. - 1./(1. + exp(-z) )     ! NOT a good way to do it
      return
      end function func
      subroutine norms(x,m,l1,l2)   ! dummy names
      integer, intent(in) :: m      ! input only
      real, intent(out) :: l1,l2    ! output only
      real, dimension(m) :: x       ! variable dimension -- one way
      l1 = 0.
      l2 = 0.
      do i = 1,m
      l1 = l1 + abs(x(i))
      l2 = l2 + x(i)*x(i)
      end do  ! loop on i
      l2 = sqrt(l2)
      return
      end subroutine norms