我正在使用此代码计算日出和日落时间。
// Get the daylight status of the current time.
bool
SunLight::CalculateDaylightStatus()
{
// Calculate the current time of day.
time_t currentTime = time(NULL);
m_LocalTime = localtime(¤tTime);
// Initialize the sunrise and set times.
*m_Sunrise = *m_LocalTime;
*m_Sunset = *m_LocalTime;
// Flags to check whether sunrise or set available on the day or not.
m_IsSunrise = false;
m_IsSunset = false;
m_RiseAzimuth = 0.0;
m_SetAzimuth = 0.0;
for (unsigned int i = 0; i < 3; i++)
{
m_RightAscention[i] = 0.0;
m_Decension[i] = 0.0;
m_VHz[i] = 0.0;
}
for (unsigned int i = 0; i < 2; i++)
{
m_SunPositionInSky[i] = 0.0;
m_RiseTime[i] = 0;
m_SetTime[i] = 0;
}
// Calculate the sunrise and set times.
CalculateSunRiseSetTimes();
return (mktime(m_LocalTime) >= mktime(m_Sunrise) && mktime(m_LocalTime) < mktime(m_Sunset))
? true
: false;
}
//---------------------------------------------------------------------
bool
SunLight::CalculateSunRiseSetTimes()
{
double zone = timezone/3600 - m_LocalTime->tm_isdst;
// Julian day relative to Jan 1.5, 2000.
double jd = GetJulianDay() - 2451545;
if ((Sign(zone) == Sign(m_Config->Longitude())) && (zone != 0))
{
return false;
}
double tz = zone / 24;
// Centuries since 1900.0
double ct = jd / 36525 + 1;
// Local sidereal time.
double t0 = LocalSiderealTimeForTimeZone(jd, tz, m_Config->Longitude()/360);
// Get sun position at start of day.
jd += tz;
// Calculate the position of the sun.
CalculateSunPosition(jd, ct);
double ra0 = m_SunPositionInSky[0];
double dec0 = m_SunPositionInSky[1];
// Get sun position at end of day.
jd += 1;
// Calculate the position of the sun.
CalculateSunPosition(jd, ct);
double ra1 = m_SunPositionInSky[0];
double dec1 = m_SunPositionInSky[1];
// make continuous
if (ra1 < ra0)
ra1 += 2 * M_PI;
m_RightAscention[0] = ra0;
m_Decension[0] = dec0;
// check each hour of this day
for (int k = 0; k < 24; k++)
{
m_RightAscention[2] = ra0 + (k + 1) * (ra1 - ra0) / 24;
m_Decension[2] = dec0 + (k + 1) * (dec1 - dec0) / 24;
m_VHz[2] = TestHour(k, t0, m_Config->Latitude());
// advance to next hour
m_RightAscention[0] = m_RightAscention[2];
m_Decension[0] = m_Decension[2];
m_VHz[0] = m_VHz[2];
}
// Update the tm structure with time values.
m_Sunrise->tm_hour = m_RiseTime[0];
m_Sunrise->tm_min = m_RiseTime[1];
m_Sunset->tm_hour = m_SetTime[0];
m_Sunset->tm_min = m_SetTime[1];
// neither sunrise nor sunset
if ((!m_IsSunrise) && (!m_IsSunset))
{
// Sun down all day.
if (m_VHz[2] < 0)
m_IsSunset = true;
// Sun up all day.
else
m_IsSunrise = true;
}
return true;
}
//---------------------------------------------------------------------
int
SunLight::Sign(double value)
{
if (value > 0.0)
return 1;
else if (value < 0.0)
return -1;
else
return 0;
}
//---------------------------------------------------------------------
// Local Sidereal Time for zone.
double
SunLight::LocalSiderealTimeForTimeZone(double jd, double z, double lon)
{
double s = 24110.5 + 8640184.812999999 * jd / 36525 + 86636.6 * z + 86400 * lon;
s = s / 86400;
s = s - floor(s);
return s * 360 * cDegToRad;
}
//---------------------------------------------------------------------
// Determine Julian day from calendar date
// (Jean Meeus, "Astronomical Algorithms", Willmann-Bell, 1991).
double
SunLight::GetJulianDay()
{
int month = m_LocalTime->tm_mon + 1;
int day = m_LocalTime->tm_mday;
int year = 1900 + m_LocalTime->tm_year;
bool gregorian = (year < 1583) ? false : true;
if ((month == 1) || (month == 2))
{
year = year - 1;
month = month + 12;
}
double a = floor((double)year / 100);
double b = 0;
if (gregorian)
b = 2 - a + floor(a / 4);
else
b = 0.0;
double jd = floor(365.25 * (year + 4716))
+ floor(30.6001 * (month + 1))
+ day + b - 1524.5;
return jd;
}
//---------------------------------------------------------------------
// Sun's position using fundamental arguments
// (Van Flandern & Pulkkinen, 1979).
void
SunLight::CalculateSunPosition(double jd, double ct)
{
double g, lo, s, u, v, w;
lo = 0.779072 + 0.00273790931 * jd;
lo = lo - floor(lo);
lo = lo * 2 * M_PI;
g = 0.993126 + 0.0027377785 * jd;
g = g - floor(g);
g = g * 2 * M_PI;
v = 0.39785 * sin(lo);
v = v - 0.01 * sin(lo - g);
v = v + 0.00333 * sin(lo + g);
v = v - 0.00021 * ct * sin(lo);
u = 1 - 0.03349 * cos(g);
u = u - 0.00014 * cos(2 * lo);
u = u + 0.00008 * cos(lo);
w = -0.0001 - 0.04129 * sin(2 * lo);
w = w + 0.03211 * sin(g);
w = w + 0.00104 * sin(2 * lo - g);
w = w - 0.00035 * sin(2 * lo + g);
w = w - 0.00008 * ct * sin(g);
// compute sun's right ascension
s = w / sqrt(u - v * v);
m_SunPositionInSky[0] = lo + atan(s / sqrt(1 - s * s));
// ...and declination
s = v / sqrt(u);
m_SunPositionInSky[1] = atan(s / sqrt(1 - s * s));
}
//---------------------------------------------------------------------
// Test an hour for an event.
double
SunLight::TestHour(int k, double t0, double prmLatitude)
{
double ha[3];
double a, b, c, d, e, s, z;
double time;
double az, dz, hz, nz;
int hr, min;
ha[0] = t0 - m_RightAscention[0] + k * cK1;
ha[2] = t0 - m_RightAscention[2] + k * cK1 + cK1;
ha[1] = (ha[2] + ha[0]) / 2; // hour angle at half hour
m_Decension[1] = (m_Decension[2] + m_Decension[0]) / 2; // declination at half hour
s = sin(prmLatitude * cDegToRad);
c = cos(prmLatitude * cDegToRad);
z = cos(90.833 * cDegToRad); // refraction + sun semi-diameter at horizon
if (k <= 0)
m_VHz[0] = s * sin(m_Decension[0]) + c * cos(m_Decension[0]) * cos(ha[0]) - z;
m_VHz[2] = s * sin(m_Decension[2]) + c * cos(m_Decension[2]) * cos(ha[2]) - z;
if (Sign(m_VHz[0]) == Sign(m_VHz[2]))
return m_VHz[2]; // no event this hour
m_VHz[1] = s * sin(m_Decension[1]) + c * cos(m_Decension[1]) * cos(ha[1]) - z;
a = 2 * m_VHz[0] - 4 * m_VHz[1] + 2 * m_VHz[2];
b = -3 * m_VHz[0] + 4 * m_VHz[1] - m_VHz[2];
d = b * b - 4 * a * m_VHz[0];
if (d < 0)
return m_VHz[2]; // no event this hour
d = sqrt(d);
e = (-b + d) / (2 * a);
if ((e > 1) || (e < 0))
e = (-b - d) / (2 * a);
time = (double)k + e + (double)1 / (double)120; // time of an event
hr = (int)floor(time);
min = (int)floor((time - hr) * 60);
hz = ha[0] + e * (ha[2] - ha[0]); // azimuth of the sun at the event
nz = -cos(m_Decension[1]) * sin(hz);
dz = c * sin(m_Decension[1]) - s * cos(m_Decension[1]) * cos(hz);
az = atan2(nz, dz) / cDegToRad;
if (az < 0) az = az + 360;
if ((m_VHz[0] < 0) && (m_VHz[2] > 0))
{
m_RiseTime[0] = hr;
m_RiseTime[1] = min;
m_RiseAzimuth = az;
m_IsSunrise = true;
}
if ((m_VHz[0] > 0) && (m_VHz[2] < 0))
{
m_SetTime[0] = hr;
m_SetTime[1] = min;
m_SetAzimuth = az;
m_IsSunset = true;
}
return m_VHz[2];
}
//---------------------------------------------------------------------
我需要在公式中引入高度，以获得更准确的结果。有人可以给我一个快速的解决方案，我必须修改以在公式中添加高度吗？
答案 0 :(得分：2)
该算法无法计算日出和日落的时间。你需要的是Jean Meeus' book "Astronomical Algorithms"。你需要考虑观察者的经度和纬度，动态时间和世界时间之间的差异，以及地球轨道的偏心率，以获得低精度的结果。
答案 1 :(得分：0)
这似乎被称为sunrise equation。这篇Wiki文章中的公式简单得令人难以置信，它们确实考虑了地理位置。