dyno

// ported date utility function from http://howardhinnant.github.io/date_algorithms.html

// @param z   Days since epoch
// @return    Civic date tuple [y, m, d]
local civil_from_days(z) = (
  local z1 = z + 719468;
  local era = std.floor((if z1 >= 0 then z1 else z1 - 146096) / 146097);
  local doe = (z1 - era * 146097);  // [0, 146096]
  local yoe = std.floor((doe - std.floor(doe / 1460) + std.floor(doe / 36524) - std.floor(doe / 146096)) / 365);  // [0, 399]
  local y = yoe + era * 400;