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#include "calendar.h"
double Julian::d[23][5]={
{-4000, 108371.700000, -13036.800000, 392.000000, 0.000000},
{ -500, 17201.000000, -627.820000, 16.170000, -0.341300},
{ -150, 12200.600000, -346.410000, 5.403000, -0.159300},
{ 150, 9113.800000, -328.130000, -1.647000, 0.037700},
{ 500, 5707.500000, -391.410000, 0.915000, 0.314500},
{ 900, 2203.400000, -283.450000, 13.034000, -0.177800},
{ 1300, 490.100000, -57.350000, 2.085000, -0.007200},
{ 1600, 120.000000, -9.810000, -1.532000, 0.140300},
{ 1700, 10.200000, -0.910000, 0.510000, -0.037000},
{ 1800, 13.400000, -0.720000, 0.202000, -0.019300},
{ 1830, 7.800000, -1.810000, 0.416000, -0.024700},
{ 1860, 8.300000, -0.130000, -0.406000, 0.029200},
{ 1880, -5.400000, 0.320000, -0.183000, 0.017300},
{ 1900, -2.300000, 2.060000, 0.169000, -0.013500},
{ 1920, 21.200000, 1.690000, -0.304000, 0.016700},
{ 1940, 24.200000, 1.220000, -0.064000, 0.003100},
{ 1960, 33.200000, 0.510000, 0.231000, -0.010900},
{ 1980, 51.000000, 1.290000, -0.026000, 0.003200},
{ 2000, 63.870000, 0.100000, 0.000000, 0.000000},
{ 2005, 64.700000, 0.210000, 0.000000, 0.000000},
{ 2012, 66.800000, 0.220000, 0.000000, 0.000000},
{ 2018, 69.000000, 0.360000, 0.000000, 0.000000},
{ 2028, 72.600000, 0.000000, 0.000000, 0.000000}
};
double Julian::dt_ext(int y,double jsd)
{
double dy=(double)(y-1820)/100.0;
return -20+jsd*dy*dy;
}
//计算力学时与世界时之差,传入年份
double Julian::delta_t(int y)
{
int y0=d[22][0];//表中最后一行的年份
double t0=d[22][1];//表中最后一行的delta_t
double jsd;
if(y>y0)
{
jsd=31;
if(y-y0>100)
{
return dt_ext(y,jsd);
}
double v=dt_ext(y,jsd);
double dv=dt_ext(y0,jsd)-t0;
return v-dv*(y0+100-y)/100;
}
double res;
for(int i=0;i<22;i++)
{
if(y<d[i+1][0])
{
break;
}
double t1=(y-d[i][0])/(d[i+1][0]-d[i][0])*10;
double t2=t1*t1;
double t3=t2*t1;
res=d[i][1]+d[i][2]*t1+d[i][3]*t2+d[i][4]*t3;
}
return res;
}
// 计算儒略日
double Julian::getJulianDay(time_t time)
{
double t=(double)time;
return (double)t/86400.0+2440587.5;
}
// 计算儒略千年数
double Julian::getJulianKiloYear(time_t time)
{
double jd = getJulianDay(time);
return (double)(jd-2451545.0)/365250.0;
}
//儒略千年数转时间戳
time_t Julian::kiloYearToTime(double t,int year)
{
double jd=t*365250.0+2451545.0;
time_t time=(time_t)((jd-2440587.5)*86400.0-delta_t(year));
return time;
}
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