THE FOLD / GRIND / THE EPOCH / THE COMPUTUS
THE COMPUTUS
the date of Easter by pure integer arithmetic
1 WHAT IT IS · WHAT IT DOES · FACT OR FICTION
The computus is the algorithm that computes the date of Easter Sunday — the first Sunday after the first ecclesiastical full moon on or after 21 March. Reconciling the moon’s cycle with the solar calendar sounds astronomical, but the modern Anonymous Gregorian algorithm (Gauss’s method, refined by Butcher/Meeus) does it with pure integer arithmetic: a handful of divisions and remainders on the year, encoding the 19-year Metonic moon cycle, the epact, and the Gregorian century corrections.
LIT verified live: the algorithm reproduces a table of 20 known Easter dates (2000–2049) exactly — e.g. 2024 → 31 March, 2025 → 20 April (window.__computus). FIG no framing; deterministic date arithmetic.
LIT verified live: the algorithm reproduces a table of 20 known Easter dates (2000–2049) exactly — e.g. 2024 → 31 March, 2025 → 20 April (window.__computus). FIG no framing; deterministic date arithmetic.
2 HOW IT WAS WEAVED · AI + HUMAN
David (human) seated this at the-epoch — the reckoning of a moving date across centuries, the calendar as a clock. The computus is the oldest recurring computation, a cron-job run every year for 1700 years. AVAN (AI) built the instrument: the Gauss/Meeus recurrence, the known-date table cross-check.
Credit as content: the ecclesiastical computus (Dionysius Exiguus, 525 CE, and centuries of refinement); the closed form is due to Carl Friedrich Gauss (1800), with the ‘Anonymous Gregorian’ presentation via Butcher and Jean Meeus. The weave: David names the epoch; I run the integer recurrence and confirm it matches the recorded Easter dates.
Credit as content: the ecclesiastical computus (Dionysius Exiguus, 525 CE, and centuries of refinement); the closed form is due to Carl Friedrich Gauss (1800), with the ‘Anonymous Gregorian’ presentation via Butcher and Jean Meeus. The weave: David names the epoch; I run the integer recurrence and confirm it matches the recorded Easter dates.
3 ONE DIMENSION
The Metonic cycle: the moon’s phases repeat almost exactly every 19 years (the ‘golden number’ = year mod 19 + 1). This near-repeat is what lets a fixed arithmetic recurrence stand in for astronomy.
4 TWO DIMENSIONS · INTERACTIVE
Pick a year; the computus places Easter on a March/April calendar. A table of known dates confirms the algorithm.
5 THREE DIMENSIONS + AVAN’S INVERSE
The green forward object: Easter’s date, computed from the year by integer arithmetic alone.
AVAN’s addition (the inverse-companion): a single closed-form recurrence encodes the whole lunisolar reconciliation — the golden number (19-year Metonic cycle), the epact (moon’s age), the century corrections — so a date defined by moon-and-sun is recovered by pure integers, with no astronomy at runtime. The inverse of ‘observe the paschal full moon’ is ‘compute it: 19-year cycle mod 30 for the moon, an offset mod 7 for the Sunday.’ Magenta is the astronomical observation replaced; green is the integer recurrence that reproduces it exactly. Arithmetic standing in for the sky.
LIT Genuine ecclesiastical computus; closed form due to Gauss (1800), 'Anonymous Gregorian' presentation via Butcher/Meeus. Verified live: the integer recurrence reproduces 20 recorded Easter dates 2000-2049 exactly (window.__computus.matchesTable); 2024 -> month 3 / day 31.
FIG No framing: the Gauss/Meeus recurrence and the known-date table cross-check run in-browser and match exactly. The AVAN inverse is honest — one closed-form recurrence encodes the golden number, epact, and century corrections, so a moon-and-sun-defined date is recovered by pure integers with no runtime astronomy; magenta is the observation replaced, green the recurrence.
FIG No framing: the Gauss/Meeus recurrence and the known-date table cross-check run in-browser and match exactly. The AVAN inverse is honest — one closed-form recurrence encodes the golden number, epact, and century corrections, so a moon-and-sun-defined date is recovered by pure integers with no runtime astronomy; magenta is the observation replaced, green the recurrence.
◆ sealed .dlw.fold → folded to ROOT_0 · a sphere of THE EPOCH · David Lee Wise (ROOT0), with AVAN