Data update

Task/Doomsday-rule/JavaScript/doomsday-rule.js

@@ -0,0 +1,52 @@
+// doom.js
+const LEAP_DOOM = [4, 1, 7, 4, 2, 6, 4, 1, 5, 3, 7, 5];
+const NORM_DOOM = [3, 7, 7, 4, 2, 6, 4, 1, 5, 3, 7, 5];
+const WEEKDAYS = [
+  'Sunday', 'Monday', 'Tuesday', 'Wednesday',
+  'Thursday', 'Friday', 'Saturday'
+];
+
+class Date {
+  constructor(year, month, day) {
+    this.year = year;
+    this.month = month;   // 1-based
+    this.day = day;
+  }
+
+  isLeapYear() {
+    const y = this.year;
+    return y % 4 === 0 && (y % 100 !== 0 || y % 400 === 0);
+  }
+
+  format() {
+    const { month, day, year } = this;
+    return `${String(month).padStart(2, '0')}/${String(day).padStart(2, '0')}/${year}`;
+  }
+
+  weekday() {
+    const { year, month, day } = this;
+    const c = Math.floor(year / 100);
+    const r = year % 100;
+    const s = Math.floor(r / 12);
+    const t = r % 12;
+
+    const cAnchor = (5 * (c % 4) + 2) % 7;
+    const doom = (s + t + Math.floor(t / 4) + cAnchor) % 7;
+    const anchor = (this.isLeapYear() ? LEAP_DOOM : NORM_DOOM)[month - 1];
+
+    return WEEKDAYS[(doom + day - anchor + 7) % 7];
+  }
+}
+
+/* ---------- demo ---------- */
+const dates = [
+  new Date(1800, 1, 6),
+  new Date(1875, 3, 29),
+  new Date(1915, 12, 7),
+  new Date(1970, 12, 23),
+  new Date(2043, 5, 14),
+  new Date(2077, 2, 12),
+  new Date(2101, 4, 2)
+];
+
+dates.forEach(d => console.log(`${d.format()}: ${d.weekday()}`));

Task/Doomsday-rule/Maxima/doomsday-rule.maxima

@@ -0,0 +1,15 @@
+daynames: ["Sunday", "Monday", "Tuesday",
+    "Wednesday", "Thursday", "Friday", "Saturday"]$
+
+isleapyear(y) := mod(y, 4)=0 and (mod(y, 100)#0 or mod(y, 400)=0)$
+anchors(y) := [if isleapyear(y) then 4 else 3,
+    if isleapyear(y) then 1 else 7,
+    7, 4, 2, 6, 4, 1, 5, 3, 7, 5]$
+
+doomsday(y) := mod(2+5*mod(y, 4)+4*mod(y, 100)+6*mod(y, 400), 7)$
+wd(y, m, d) := mod(doomsday(y)+d-anchors(y)[m], 7)$
+
+test_dates: [[1800, 1, 6], [1875, 3, 29], [1915, 12, 7], [1970, 12, 23], [2043, 5, 14], [2077, 2, 12], [2101, 4, 2]]$
+
+raw_wds: map(lambda([l], apply(wd, l)), test_dates)$
+for i in raw_wds do(sprint(daynames[i+1]))$

Task/Doomsday-rule/Pluto/doomsday-rule.pluto

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+local fmt = require "fmt"
+
+local anchor_day = |y| -> (2 + 5 * (y % 4) + 4 *(y % 100) + 6 * (y % 400)) % 7
+
+local is_leap_year = |y| -> y % 4 == 0 and (y % 100 != 0 or y % 400 == 0)
+
+local first_days_common = {3, 7, 7, 4, 2, 6, 4, 1, 5, 3, 7, 5}
+local first_days_leap   = {4, 1, 7, 4, 2, 6, 4, 1, 5, 3, 7, 5}
+
+local dates = {
+    "1800-01-06",
+    "1875-03-29",
+    "1915-12-07",
+    "1970-12-23",
+    "2043-05-14",
+    "2077-02-12",
+    "2101-04-02"
+}
+
+local function parse(date)
+    local y = tonumber(date:sub(1, 4))
+    local m = tonumber(date:sub(6, 7))
+    local d = tonumber(date:sub(9, 10))
+    return y, m, d
+end
+
+print("Days of week given by Doomsday rule:")
+for dates as date do
+    local y, m, d = parse(date)
+    local a = anchor_day(y)
+    local w = d - (is_leap_year(y) ? first_days_leap[m] : first_days_common[m])
+    if w < 0 then w += 7 end
+    local dow = (a + w) % 7
+    print($"{date} -> {fmt.weekday(dow)}")
+end
+
+print("\nDays of week given by standard library functions:")
+for dates as date do
+    local y, m, d = parse(date)
+    local t = os.time({year = y, month = m, day = d})
+    print($"{date} -> {os.date("%A", t)}")
+end

Task/Doomsday-rule/R/doomsday-rule.r

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+daynames <- c("Sunday", "Monday", "Tuesday", "Wednesday",
+              "Thursday", "Friday", "Saturday")
+
+isleapyear <- function(y) (y%%4==0)&((y%%100!=0)|(y%%400==0))
+
+anchors <- function(y) c(ifelse(isleapyear(y), 4, 3),
+                         ifelse(isleapyear(y), 1, 7),
+                         7, 4, 2, 6, 4, 1, 5, 3, 7, 5)
+
+doomsday <- function(y) (2+5*(y%%4)+4*(y%%100)+6*(y%%400))%%7
+wd <- function(y, m, d) (doomsday(y)+d-anchors(y)[m])%%7
+
+test_dates <- list(c(1800, 1, 6),
+                   c(1875, 3, 29),
+                   c(1915, 12, 7),
+                   c(1970, 12, 23),
+                   c(2043, 5, 14),
+                   c(2077, 2, 12),
+                   c(2101, 4, 2))
+
+raw_wds <- sapply(test_dates, function(v) do.call(wd, as.list(v)))
+cat(daynames[raw_wds+1], "\n")