code: function j2d (jy, jm, jd) {
    const r = jalCal(jy, true)
    return g2d(r.gy, 3, r.march) + (jm - 1) * 31 - div(jm, 7) * (jm - 7) + jd - 1
  }
docs: /*
  Converts a date of the Jalaali calendar to the Julian Day number.
  
  @param jy Jalaali year (1 to 3100)
  @param jm Jalaali month (1 to 12)
  @param jd Jalaali day (1 to 29/31)
  @return Julian Day number