jd_to_commercial

# File lib/date.rb, line 458
    def jd_to_commercial(jd, sg=GREGORIAN) # :nodoc:
      a = jd_to_civil(jd - 3, sg)[0]
      y = if jd >= commercial_to_jd(a + 1, 1, 1, sg) then a + 1 else a end
      w = 1 + ((jd - commercial_to_jd(y, 1, 1, sg)) / 7).floor
      d = (jd + 1) % 7
      d = 7 if d == 0
      return y, w, d
    end