Calculate the date of Easter

easter.rb

def computus(year)
  a = year % 19                 # year in the 19-year metonic cycle
  k = year / 100                # century index
  p = (13 + 8*k) / 25           # shift of metonic cycle, add a day offset every 300 years
  q = k / 4                     # correction for non-observed leap days
  m = (15 - p + k - q) % 30     # correction to starting point each century
  d = (19*a + m) % 30           # num of days from 3/21 until full moon
  n = (4 + k - q) % 7           # find next sunday; century-based offset in weekly calc.
  b = year % 4                  # correct for leap days
  c = year % 7                  # correct for leap days
  e = (2*b + 4*c + 6*d + n) % 7 # days from `d` to next Sunday

  # historical corrections for April 26 and 25
  if (d == 29 && e == 6) || (d == 28 && e == 6 && a > 10)
    e = -1
  end

  # determinaton of the correct month for Easter
  if (22 + d + e) > 31
    return "April #{d + e - 9}"
  else
    return "March #{22 + d + e}"
  end
end

puts computus(2023)