subroutine sum_fields(map_inj,map_inf, xmin_inj, xmin_inf,map, xmin)
    use magfield
    implicit none
    type(magfield_struct), allocatable :: map_inj(:,:,:), map_inf(:,:,:)
    type(magfield_struct), allocatable :: map(:,:,:)
    type(magfield_struct) x0, xmax, xmin, dxyz(-1:1), xmin_inj, xmin_inf, diffx
    integer ntot(3), ntot_inf(3), idif(3)
    integer i,j,k,l

    forall(i=1:3)ntot(i) = size(map_inj,i)
    forall(i=1:3)ntot_inf(i) = size(map_inf,i)

         idif(1:3) = 2*(xmin_inf%x(1:3) - xmin_inj%x(1:3))
    allocate(map(1:ntot(1),1:ntot(2),1:ntot(3)))
    map(:,:,:) = map_inj(:,:,:)
    xmin%x = xmin_inj%x

    do i=1+idif(1),ntot(1)
!     write(13,'(/,a,/)')'#'
     do j=1+idif(2),ntot(2)
!     write(13,'(/,a,/)')'#'
      do k=1+idif(3),ntot(3)

       map(i,j,k)%B(1:3) = map_inj(i,j,k)%B(1:3) +  map_inf(i-idif(1),j-idif(2),k-idif(3))%B(1:3)

    diffx%x(1:3) = map_inj(i,j,k)%x(1:3) - map_inf(i-idif(1),j-idif(2),k-idif(3))%x(1:3)
    if(any(abs(diffx%x(1:3)) > 0.00001))then
       
!       print '(4(3es12.4))', map(i,j,k)%B(2), map_inj(i,j,k)%B(2), map_inf(i-idif(1),j-idif(2),k-idif(3))%B(2), &
!              map_inf(i-idif(1),j-idif(2),k-idif(3))%x(1:3),map_inj(i,j,k)%x(1:3),diffx%x
       
       write(13,'(4(3es12.4))')map(i,j,k)%B(2), map_inj(i,j,k)%B(2), map_inf(i-idif(1),j-idif(2),k-idif(3))%B(2), &
              map_inf(i-idif(1),j-idif(2),k-idif(3))%x(1:3),map_inj(i,j,k)%x(1:3),diffx%x
    endif
      end do
        end do
       end do
!      do k=1,ntot(3)

!      end do
    return
   end