anchor.diff:          lt_data%u_accumulator = 0
           lt_data%v_accumulator = 0
   
  -        current_z = step_size / 2
  +        current_z = z_bottom + step_size / 2
  +
           do i=1,n_steps
               call linear_perturbation_at_height(U,V,Nsq,current_z, fourier_terrain, lt_data)
               lt_data%u_accumulator = lt_data%u_accumulator + lt_data%u_perturb
  
positive.code:             loops_completed = 0
              write(*,*) "Percent Completed:"
              !$omp parallel default(shared) &
              !$omp private(i,j,k,z, u,v, layer_height, layer_height_bottom, layer_height_top, minimum_layer_size)
              ! $omp private(lt_data_m)
  
              ! initialization has to happen in each thread so each thread has its own copy
  
negative.code:         ! default assumes no errors in reading the LUT
          error = 0
  
          ! minimum_layer_size = options%minimum_layer_size
          minimum_layer_size = 100
          print*, "WARNING: minimum_layer_size hard coded as", minimum_layer_size
  
          ! store to make it easy to check dim sizes in read_LUT
          LUT_dims(:,1) = [nxu,nz,ny]
  