anchor.diff:          !     wfn_file = filename,
           !     nanalyse = N,
           !     blacs_block_size = block_size,
  -        !     rdm = { ... } -- L-d vector containing the sites to include in subsystem A.
  +        !     rdm = { ... }, -- L-d vector containing the sites to include in subsystem A.
  +        !     sparse_hamil = true/false
           ! }
           ! lanczos = {
           !     neigv = N,
  
positive.code:             call aot_get_val(fci_in%nlanczos_eigv, err, lua_state, fci_table, 'neigv')
              call aot_get_val(fci_in%lanczos_string_len, err, lua_state, fci_table, 'nbasis')
              call aot_get_val(fci_in%direct_lanczos, err, lua_state, fci_table, 'direct')
              call aot_table_close(lua_state, fci_table)
          end if
  
  
negative.code:         type(sys_t), pointer :: sys
          type(fci_in_t) :: fci_in
          type(reference_t) :: ref
          logical :: use_sparse_hamil, lanczos
  
          lua_state = flu_copyptr(l)
          call get_sys_t(lua_state, sys)
  
          opts = aot_table_top(lua_state)
          lanczos = aot_exists(lua_state, opts, 'lanczos')
          call read_fci_in(lua_state, opts, sys%basis, fci_in, use_sparse_hamil)
          call read_reference_t(lua_state, opts, sys, ref)
          call aot_table_close(lua_state, opts)
  
          if (lanczos) then
              calc_type = lanczos_diag
              call do_fci_lanczos(sys, fci_in, ref, use_sparse_hamil)
          else
              calc_type = exact_diag
              call do_fci_lapack(sys, fci_in, ref)
  