function gregorian_to_jalali(gy, gm, gd) {
    
    var g_d_m, jy, jm, jd, gy2, days;
    g_d_m = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
    gy2 = gm > 2 ? gy + 1 : gy;
    days =
      355666 +
      365 * gy +
      ~~((gy2 + 3) / 4) -
      ~~((gy2 + 99) / 100) +
      ~~((gy2 + 399) / 400) +
      gd +
      g_d_m[gm - 1];
    jy = -1595 + 33 * ~~(days / 12053);
    days %= 12053;
    jy += 4 * ~~(days / 1461);
    days %= 1461;
    if (days > 365) {
      jy += ~~((days - 1) / 365);
      days = (days - 1) % 365;
    }
    if (days < 186) {
      jm = 1 + ~~(days / 31);
      jd = 1 + (days % 31);
    } else {
      jm = 7 + ~~((days - 186) / 30);
      jd = 1 + ((days - 186) % 30);
    }
    return [jy, jm, jd];
  }

  export {gregorian_to_jalali}