AmLich.php

AmLich.php

/**
 * Thư viện AmLich.
 * Example 
 * $am_lich = new AmLich();
 * $al = $am_lich->convertSolar2Lunar(30, 10, 2023, 7.0);
 * Ngày: $al[0], Tháng: $al[1], Năm: $al[2]
 */
class AmLich {

  public function INT($d) {
    return floor($d);
  }

  public function jdFromDate($dd, $mm, $yy) {
    $a = $this->INT((14 - $mm) / 12);
    $y = $yy + 4800 - $a;
    $m = $mm + 12 * $a - 3;
    $jd = $dd + $this->INT((153 * $m + 2) / 5) + 365 * $y + $this->INT($y / 4) - $this->INT($y / 100) + $this->INT($y / 400) - 32045;
    if ($jd < 2299161) {
      $jd = $dd + $this->INT((153 * $m + 2) / 5) + 365 * $y + $this->INT($y / 4) - 32083;
    }
    return $jd;
  }

  public function jdToDate($jd) {
    if ($jd > 2299160) { // After 5/10/1582, Gregorian calendar
      $a = $jd + 32044;
      $b = $this->INT((4 * $a + 3) / 146097);
      $c = $a - $this->INT(($b * 146097) / 4);
    }
    else {
      $b = 0;
      $c = $jd + 32082;
    }
    $d = $this->INT((4 * $c + 3) / 1461);
    $e = $c - $this->INT((1461 * $d) / 4);
    $m = $this->INT((5 * $e + 2) / 153);
    $day = $e - $this->INT((153 * $m + 2) / 5) + 1;
    $month = $m + 3 - 12 * $this->INT($m / 10);
    $year = $b * 100 + $d - 4800 + $this->INT($m / 10);
    //echo "day = $day, month = $month, year = $year\n";
    return [$day, $month, $year];
  }

  public function getNewMoonDay($k, $timeZone) {
    $T = $k / 1236.85; // Time in Julian centuries from 1900 January 0.5
    $T2 = $T * $T;
    $T3 = $T2 * $T;
    $dr = M_PI / 180;
    $Jd1 = 2415020.75933 + 29.53058868 * $k + 0.0001178 * $T2 - 0.000000155 * $T3;
    $Jd1 = $Jd1 + 0.00033 * sin((166.56 + 132.87 * $T - 0.009173 * $T2) * $dr); // Mean new moon
    $M = 359.2242 + 29.10535608 * $k - 0.0000333 * $T2 - 0.00000347 * $T3; // Sun's mean anomaly
    $Mpr = 306.0253 + 385.81691806 * $k + 0.0107306 * $T2 + 0.00001236 * $T3; // Moon's mean anomaly
    $F = 21.2964 + 390.67050646 * $k - 0.0016528 * $T2 - 0.00000239 * $T3; // Moon's argument of latitude
    $C1 = (0.1734 - 0.000393 * $T) * sin($M * $dr) + 0.0021 * sin(2 * $dr * $M);
    $C1 = $C1 - 0.4068 * sin($Mpr * $dr) + 0.0161 * sin($dr * 2 * $Mpr);
    $C1 = $C1 - 0.0004 * sin($dr * 3 * $Mpr);
    $C1 = $C1 + 0.0104 * sin($dr * 2 * $F) - 0.0051 * sin($dr * ($M + $Mpr));
    $C1 = $C1 - 0.0074 * sin($dr * ($M - $Mpr)) + 0.0004 * sin($dr * (2 * $F + $M));
    $C1 = $C1 - 0.0004 * sin($dr * (2 * $F - $M)) - 0.0006 * sin($dr * (2 * $F + $Mpr));
    $C1 = $C1 + 0.0010 * sin($dr * (2 * $F - $Mpr)) + 0.0005 * sin($dr * (2 * $Mpr + $M));
    if ($T < -11) {
      $deltat = 0.001 + 0.000839 * $T + 0.0002261 * $T2 - 0.00000845 * $T3 - 0.000000081 * $T * $T3;
    }
    else {
      $deltat = -0.000278 + 0.000265 * $T + 0.000262 * $T2;
    };
    $JdNew = $Jd1 + $C1 - $deltat;
    //echo "JdNew = $JdNew\n";
    return $this->INT($JdNew + 0.5 + $timeZone / 24);
  }

  public function getSunLongitude($jdn, $timeZone) {
    $T = ($jdn - 2451545.5 - $timeZone / 24) / 36525; // Time in Julian centuries from 2000-01-01 12:00:00 GMT
    $T2 = $T * $T;
    $dr = M_PI / 180; // degree to radian
    $M = 357.52910 + 35999.05030 * $T - 0.0001559 * $T2 - 0.00000048 * $T * $T2; // mean anomaly, degree
    $L0 = 280.46645 + 36000.76983 * $T + 0.0003032 * $T2; // mean longitude, degree
    $DL = (1.914600 - 0.004817 * $T - 0.000014 * $T2) * sin($dr * $M);
    $DL = $DL + (0.019993 - 0.000101 * $T) * sin($dr * 2 * $M) + 0.000290 * sin($dr * 3 * $M);
    $L = $L0 + $DL; // true longitude, degree
    //echo "\ndr = $dr, M = $M, T = $T, DL = $DL, L = $L, L0 = $L0\n";
    // obtain apparent longitude by correcting for nutation and aberration
    $omega = 125.04 - 1934.136 * $T;
    $L = $L - 0.00569 - 0.00478 * sin($omega * $dr);
    $L = $L * $dr;
    $L = $L - M_PI * 2 * ($this->INT($L / (M_PI * 2))); // Normalize to (0, 2*PI)
    return $this->INT($L / M_PI * 6);
  }

  public function getLunarMonth11($yy, $timeZone) {
    $off = $this->jdFromDate(31, 12, $yy) - 2415021;
    $k = $this->INT($off / 29.530588853);
    $nm = $this->getNewMoonDay($k, $timeZone);
    $sunLong = $this->getSunLongitude($nm, $timeZone); // sun longitude at local midnight
    if ($sunLong >= 9) {
      $nm = $this->getNewMoonDay($k - 1, $timeZone);
    }
    return $nm;
  }

  public function getLeapMonthOffsetnth11($a11, $timeZone) {
    $k = $this->INT(($a11 - 2415021.076998695) / 29.530588853 + 0.5);
    $last = 0;
    $i = 1; // We start with the month following lunar month 11
    $arc = $this->getSunLongitude($this->getNewMoonDay($k + $i, $timeZone), $timeZone);
    do {
      $last = $arc;
      $i = $i + 1;
      $arc = $this->getSunLongitude($this->getNewMoonDay($k + $i, $timeZone), $timeZone);
    } while ($arc != $last && $i < 14);
    return $i - 1;
  }

  /* Comvert solar date dd/mm/yyyy to the corresponding lunar date */
  public function convertSolar2Lunar($dd, $mm, $yy, $timeZone) {
    $dayNumber = $this->jdFromDate($dd, $mm, $yy);
    $k = $this->INT(($dayNumber - 2415021.076998695) / 29.530588853);
    $monthStart = $this->getNewMoonDay($k + 1, $timeZone);
    if ($monthStart > $dayNumber) {
      $monthStart = $this->getNewMoonDay($k, $timeZone);
    }
    $a11 = $this->getLunarMonth11($yy, $timeZone);
    $b11 = $a11;
    if ($a11 >= $monthStart) {
      $lunarYear = $yy;
      $a11 = $this->getLunarMonth11($yy - 1, $timeZone);
    }
    else {
      $lunarYear = $yy + 1;
      $b11 = $this->getLunarMonth11($yy + 1, $timeZone);
    }
    $lunarDay = $dayNumber - $monthStart + 1;
    $diff = $this->INT(($monthStart - $a11) / 29);
    $lunarLeap = 0;
    $lunarMonth = $diff + 11;
    if ($b11 - $a11 > 365) {
      $leapMonthDiff = $this->getLeapMonthOffsetnth11($a11, $timeZone);
      if ($diff >= $leapMonthDiff) {
        $lunarMonth = $diff + 10;
        if ($diff == $leapMonthDiff) {
          $lunarLeap = 1;
        }
      }
    }
    if ($lunarMonth > 12) {
      $lunarMonth = $lunarMonth - 12;
    }
    if ($lunarMonth >= 11 && $diff < 4) {
      $lunarYear -= 1;
    }
    return [$lunarDay, $lunarMonth, $lunarYear, $lunarLeap];
  }

  /* Convert a lunar date to the corresponding solar date */
  public function convertLunar2Solar($lunarDay, $lunarMonth, $lunarYear, $lunarLeap, $timeZone) {
    if ($lunarMonth < 11) {
      $a11 = $this->getLunarMonth11($lunarYear - 1, $timeZone);
      $b11 = $this->getLunarMonth11($lunarYear, $timeZone);
    }
    else {
      $a11 = $this->getLunarMonth11($lunarYear, $timeZone);
      $b11 = $this->getLunarMonth11($lunarYear + 1, $timeZone);
    }
    $k = $this->INT(0.5 + ($a11 - 2415021.076998695) / 29.530588853);
    $off = $lunarMonth - 11;
    if ($off < 0) {
      $off += 12;
    }
    if ($b11 - $a11 > 365) {
      $leapOff = $this->getLeapMonthOffsetnth11($a11, $timeZone);
      $leapMonth = $leapOff - 2;
      if ($leapMonth < 0) {
        $leapMonth += 12;
      }
      if ($lunarLeap != 0 && $lunarMonth != $leapMonth) {
        return [0, 0, 0];
      }
      else {
        if ($lunarLeap != 0 || $off >= $leapOff) {
          $off += 1;
        }
      }
    }
    $monthStart = $this->getNewMoonDay($k + $off, $timeZone);
    return $this->jdToDate($monthStart + $lunarDay - 1);
  }

}