二十四节气——正解反解

<?php
$xingxiu =new jieqi;
// var_dump($xingxiu->getJieQi(2021,6,5));
$term_name = array(
    "小寒","大寒","立春","雨水","惊蛰","春分","清明","谷雨",
    "立夏","小满","芒种", "夏至","小暑","大暑","立秋","处暑",
    "白露","秋分","寒露","霜降","立冬","小雪","大雪","冬至");
  foreach ($term_name as $key => $value) {
     echo $value.":".$xingxiu->getJieQi2(2021,$key )."<br>";
  }  


 
    
die;

 class jieqi{
     
     /*
   * 节气通用算法
   */
  function getJieQi($_year,$month,$day)
  {
    $year = substr($_year,-2)+0;
    $coefficient = array(
      array(5.4055,2019,-1),//小寒
      array(20.12,2082,1),//大寒
      array(3.87),//立春
      array(18.74,2026,-1),//雨水
      array(5.63),//惊蛰
      array(20.646,2084,1),//春分
      array(4.81),//清明
      array(20.1),//谷雨
      array(5.52,1911,1),//立夏
      array(21.04,2008,1),//小满
      array(5.678,1902,1),//芒种
      array(21.37,1928,1),//夏至
      array(7.108,2016,1),//小暑
      array(22.83,1922,1),//大暑
      array(7.5,2002,1),//立秋
      array(23.13),//处暑
      array(7.646,1927,1),//白露
      array(23.042,1942,1),//秋分
      array(8.318),//寒露
      array(23.438,2089,1),//霜降
      array(7.438,2089,1),//立冬
      array(22.36,1978,1),//小雪
      array(7.18,1954,1),//大雪
      array(21.94,2021,-1)//冬至
    );
    
//     计算公式：[Y*D+C]-L
// 公式解读：年数的后2位乘0.2422加3.87取整数减闰年数。21世纪C值=3.87，22世纪C值=4.15。
//https://weibo.com/ttarticle/p/show?id=2309404346851301159219
    $term_name = array(
    "小寒","大寒","立春","雨水","惊蛰","春分","清明","谷雨",
    "立夏","小满","芒种","夏至","小暑","大暑","立秋","处暑",
    "白露","秋分","寒露","霜降","立冬","小雪","大雪","冬至");
    
    $idx1 = ($month-1)*2;
    
    $_leap_value = floor(($year-1)/4);//计算闰年
    
    $day1 = floor($year*0.2422+$coefficient[$idx1][0])-$_leap_value;
    
    
    if(isset($coefficient[$idx1][1])&&$coefficient[$idx1][1]==$_year) $day1 += $coefficient[$idx1][2];
    
    
    $day2 = floor($year*0.2422+$coefficient[$idx1+1][0])-$_leap_value;
    if(isset($coefficient[$idx1+1][1])&&$coefficient[$idx1+1][1]==$_year) $day1 += $coefficient[$idx1+1][2];
    //echo __FILE__.'->'.__LINE__.' $day1='.$day1,',$day2='.$day2.'<br/>'.chr(10);
    $data=array();
    if($day==$day1){
      $data['name1']=$term_name[$idx1];
      $data['name2']=$term_name[$idx1];
    } 
    return $data;
  } 
    /*
   * 节气通用算法
   */
  function getJieQi2($_year,$idx1)
  {
    $year = substr($_year,-2)+0;
    $coefficient = array(
      array(5.4055,2019,-1),//小寒
      array(20.12,2082,1),//大寒
      array(3.87),//立春
      array(18.74,2026,-1),//雨水
      array(5.63),//惊蛰
      array(20.646,2084,1),//春分
      array(4.81),//清明
      array(20.1),//谷雨
      array(5.52,1911,1),//立夏
      array(21.04,2008,1),//小满
      array(5.678,1902,1),//芒种
      array(21.37,1928,1),//夏至
      array(7.108,2016,1),//小暑
      array(22.83,1922,1),//大暑
      array(7.5,2002,1),//立秋
      array(23.13),//处暑
      array(7.646,1927,1),//白露
      array(23.042,1942,1),//秋分
      array(8.318),//寒露
      array(23.438,2089,1),//霜降
      array(7.438,2089,1),//立冬
      array(22.36,1978,1),//小雪
      array(7.18,1954,1),//大雪
      array(21.94,2021,-1)//冬至
    );
   
    $term_name = array(
    "小寒","大寒","立春","雨水","惊蛰","春分","清明","谷雨",
    "立夏","小满","芒种","夏至","小暑","大暑","立秋","处暑",
    "白露","秋分","寒露","霜降","立冬","小雪","大雪","冬至");
 
    $month =floor(($idx1/2)+1);
 
    
    $_leap_value = floor(($year-1)/4);//计算闰年数量
    
    $day1 = floor($year*0.2422+$coefficient[$idx1][0])-$_leap_value;
    
     return $month."月".$day1;
  
  } 
  
 }