ofstream file;
  if (is_root) {
    ostringstream buf;
    buf << out_dir << "/norms.it" << setw(6) << setfill('0') << cctk_iteration
        << ".tsv";
    const string filename = buf.str();
    file = ofstream(filename);
    file << "# 1:iteration"
         << "\t"
         << "2:time"
         << "\t"
         << "3:varname"
         << "\t"
         << "4:min"
         << "\t"
         << "5:max"
         << "\t"
         << "6:sum"
         << "\t"
         << "7:avg"
         << "\t"
         << "8:stddev"
         << "\t"
         << "9:volume"
         << "\t"
         << "10:maxabs"
         << "\t"
         << "11:L1norm"
         << "\t"
         << "12:L2norm"
         << "\n";
  }

    cGroup group;
    int ierr = CCTK_GroupData(gi, &group);
    assert(!ierr);
    if (group.grouptype != CCTK_GF)

    if (CCTK_GroupTypeI(gi) != CCTK_GF)

        cout << "  "
             << unique_ptr<char>(CCTK_FullName(groupdata.firstvarindex + vi))
                    .get()
             << ": maxabs=" << red.maxabs << " sum=" << red.sum
             << " vol=" << red.vol << "\n";

        file << cctk_iteration << "\t" << cctk_time << "\t"
             << CCTK_FullVarName(groupdata.firstvarindex + vi) << "\t"
             << red.min << "\t" << red.max << "\t" << red.sum << "\t"
             << red.avg() << "\t" << red.sdv() << "\t" << red.norm0() << "\t"
             << red.norm1() << "\t" << red.norm2() << "\t" << red.norm_inf()
             << "\n";

  if (is_root)
    file.close();