def gcal2jd(year, month, day):
    year = int(year)
    month = int(month)
    day = int(day)
    a = ipart((month - 14) / 12.0)
    jd = ipart((1461 * (year + 4800 + a)) / 4.0)
    jd += ipart((367 * (month - 2 - 12 * a)) / 12.0)
    x = ipart((year + 4900 + a) / 100.0)
    jd -= ipart((3 * x) / 4.0)
    jd += day - 2432075.5
    jd -= 0.5
    return MJD_0, jd