# File lib/date.rb, line 432
  def self.commercial_to_jd(y, w, d, ns=GREGORIAN)
    jd = civil_to_jd(y, 1, 4, ns)
    (jd - (((jd - 1) + 1) % 7)) +
      7 * (w - 1) +
      (d - 1)
  end