Temporal Coordinates

• Code library performing calendar translations: Standard Java 8 and above. It supports Hijrah, Japanese, Minguo and Thai Buddhist calendars [1], with extension possibilities. Conversions between those calendar work well (I just tested). They also have an interesting discussion about how they handle the leap second problem, under the "Time scale" section of [2]: "On days that do have a leap second, the leap second is spread equally over the last 1000 seconds of the day, maintaining the appearance of exactly 86400 seconds per day."
  • [1] https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/time/chrono/package-summary.html
  • [2] https://docs.oracle.com/en/java/javase/16/docs/api/java.base/java/time/Instant.html
  • Contributed by Martin Desruisseaux
• Calendrical Calculations: The Ultimate Edition by Edward M. Reingold and Nachum Dershowitz, 3rd edition, keeps getting enhanced and expanded. Accompanying algorithms are carefully developed and then documented in easy-to-read (really) LISP.
  • The current blurb on Amazon: An invaluable resource for working programmers, as well as a fount of useful algorithmic tools for computer scientists, astronomers, and other calendar enthusiasts, The Ultimate Edition updates and expands the previous edition to achieve more accurate results and present new calendar variants. The book now includes coverage of Unix dates, Italian time, the Akan, Icelandic, Saudi Arabian Umm al-Qura, and Babylonian calendars. There are also expanded treatments of the observational Islamic and Hebrew calendars and brief discussions of the Samaritan and Nepalese calendars. Several of the astronomical functions have been rewritten to produce more accurate results and to include calculations of moonrise and moonset. The authors frame the calendars of the world in a completely algorithmic form, allowing easy conversion among these calendars and the determination of secular and religious holidays. LISP code for all the algorithms is available in machine-readable form.
  • Contributed by Martin Birkel