This is makeindex, version 2.15 [TeX Live 2021] (kpathsea + Thai support).
Scanning input file Sophus.idx....done (27 entries accepted, 0 rejected).
Sorting entries....done (124 comparisons).
Generating output file Sophus.ind....done (61 lines written, 0 warnings).
Output written in Sophus.ind.
Transcript written in Sophus.ilg.
