subroutine beam_moments(beam, bunch_moments)
  use bmad
  use beam_mod
  use multibunch_mod

  implicit none
  type (beam_struct) beam
  type(moment_struct), allocatable :: bunch_moments(:)
  integer i,j,k,n



  do j = 1, size(beam%bunch)  ! loop over bunches
    bunch_moments(j)%sigma(:,:)=0.
    bunch_moments(j)%ave(:) = 0.
    bunch_moments(j)%sigma_t = 0
    bunch_moments(j)%ave_t = 0
     n=0 !number of alive particles
     do i = 1, size(beam%bunch(j)%particle) ! loop over particles in bunch j
        if(beam%bunch(j)%particle(i)%state == alive$)then
           bunch_moments(j)%ave(1:6)=bunch_moments(j)%ave(1:6) + beam%bunch(j)%particle(i)%vec(1:6)
           bunch_moments(j)%ave_t=bunch_moments(j)%ave_t + beam%bunch(j)%particle(i)%t
           n=n+1
        endif
     end do
     if(n == 0)return
     bunch_moments(j)%ave(1:6) = bunch_moments(j)%ave(1:6)/float(n)
     bunch_moments(j)%ave_t = bunch_moments(j)%ave_t/float(n)
  end do

  do j = 1, size(beam%bunch)  ! loop over bunches
     n=0 !number of alive particles
     do i = 1, size(beam%bunch(j)%particle) ! loop over particles in bunch j
      if(beam%bunch(j)%particle(i)%state == alive$)then
       do k=1,6
        bunch_moments(j)%sigma(1:6,k)=bunch_moments(j)%sigma(1:6,k) + (beam%bunch(j)%particle(i)%vec(1:6)-bunch_moments(j)%ave(1:6))**2
!       print '(2i10,3es12.4)',i,j,bunch_moments(j)%sigma(1,1),bunch_moments(j)%sigma(3,3),bunch_moments(j)%sigma(5,5)
       end do
        bunch_moments(j)%sigma_t=bunch_moments(j)%sigma_t + (beam%bunch(j)%particle(i)%t-bunch_moments(j)%ave_t)**2
       n=n+1
      endif !alive  
     end do
    bunch_moments(j)%sigma(1:6,1:6) = sqrt(bunch_moments(j)%sigma(1:6,1:6)/n)
    bunch_moments(j)%sigma_t = sqrt(bunch_moments(j)%sigma_t/n)
!    print '(3es12.4)',bunch_moments(j)%sigma(1,1),bunch_moments(j)%sigma(3,3),bunch_moments(j)%sigma(5,5)
    bunch_moments(j)%n_alive = n
 end do

 return
 end

!type moment_struct
! real(rp) sigma(6,6), ave(6)
! real(rp) max_sigma(6,6), min_sigma(6,6), max_ave(6), min_ave(6)
!end type