anchor.diff:    double precision :: loc(3), vel(3), mom(3), rho
   
     do k = lo(3), hi(3)
  -     loc(3) = xlo(3) + (dble(k - lo(3)) + HALF) * dx(3)
  -     do j = lo(2), hi(2)
  -        loc(2) = xlo(2) + (dble(j - lo(2)) + HALF) * dx(2)
  -        do i = lo(1), hi(1)
  -           loc(1) = xlo(1) + (dble(i - lo(1)) + HALF) * dx(1)
  +     loc(3) = xlo(3) + (dble(k - lo(3)) + HALF) * dx(3) - center(3)
  +     do j = lo(2), hi(2)
  +        loc(2) = xlo(2) + (dble(j - lo(2)) + HALF) * dx(2) - center(2)
  +        do i = lo(1), hi(1)
  +           loc(1) = xlo(1) + (dble(i - lo(1)) + HALF) * dx(1) - center(1)
   
              rho = u(i,j,k,1)
              vel = u(i,j,k,2:4) / rho
  
positive.code:   double precision :: loc(3), vel(3), mom(3), rho
  
    do k = lo(3), hi(3)
       loc(3) = xlo(3) + (dble(k - lo(3)) + HALF) * dx(3)
       do j = lo(2), hi(2)
          loc(2) = xlo(2) + (dble(j - lo(2)) + HALF) * dx(2)
          do i = lo(1), hi(1)
             loc(1) = xlo(1) + (dble(i - lo(1)) + HALF) * dx(1)
  
             rho = u(i,j,k,1)
             vel = u(i,j,k,2:4) / rho
  
negative.code:   use bl_constants_module, only: HALF
    use math_module, only: cross_product
    use probdata_module, only: inertial_velocity
    use prob_params_module, only: center
  
    implicit none
  
  