Computus (Golden Number & Epact) (教會曆算)

THE COMPUTUS — the working numbers on the almanac page of every Book of Common Prayer and every medieval calendar: the GOLDEN NUMBER (the year's place in the 19-year lunar cycle, written in gold), the EPACT (the ecclesiastical moon's age at the year's opening — the Gregorian reform's central device, Julian epact alongside, the Lilian asterisk for zero), the DOMINICAL LETTER(S) marking the Sundays (two in a leap year, the second taking over after the bissextile day), the 28-year SOLAR CYCLE, the ROMAN INDICTION, and Scaliger's JULIAN PERIOD (28×19×15 = 7980, asserted as arithmetic). THE CROWN LAW: these numbers are not decorative — this engine computes Easter FROM ITS OWN epact-and-letter table through the classical Paschal rules, Clavius's epact-24 and epact-25 exceptions included, and is proven EQUAL to the catalogue's independently verified Gregorian Easter for all 918 years 1583–2500 at load: the almanac page and the feast it exists to find, locked together. The epact register was calibrated against the published almanac values (2025's asterisk, 2026's 11, 2000's 24). Christian becomes 2. Pure compute, no LLM.

Cost: 1 TIAN Points per call. tRPC procedure computus.year.