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solar.cpp
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solar.cpp
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#include <math.h>
#define RADEG (180.0/M_PI)
#define SEC_IN_DAY (60 * 60 * 24)
#define JULIAN_DAY_1970 (2451544.5 - 10957)
class SolarThings {
private:
double longitude;
double latitude;
void from_sun(double M_moon, double e_moon, double a_moon, double N_moon, double w_moon, double i_moon, double (&moon_xy)[2]) {
double E0 = M_moon + (180 / M_PI) * e_moon * sin(M_moon / RADEG) * (1 + e_moon * cos(M_moon / RADEG));
E0 = normalize(E0);
double E1 = E0 - (E0 - (180 / M_PI) * e_moon * sin(E0 / RADEG) - M_moon) / (1 - e_moon * cos(E0 / RADEG));
E1 = normalize(E1) / RADEG;
double x = a_moon * (cos(E1) - e_moon);
double y = a_moon * (sqrt(1 - e_moon * e_moon)) * sin(E1);
double r = sqrt(x * x + y * y);
double v = atan2(y, x);
v = normalize(v * RADEG);
moon_xy[0] = r * (cos(N_moon / RADEG) * cos((v + w_moon) / RADEG) - sin(N_moon / RADEG) * sin(
(v + w_moon) / RADEG) * cos((i_moon) / RADEG));
moon_xy[1] = r * (sin(N_moon / RADEG) * cos((v + w_moon) / RADEG) + cos(N_moon / RADEG) * sin(
(v + w_moon) / RADEG) * cos(i_moon / RADEG));
}
static double normalize(double degrees) {
return fmod(degrees, 360);
}
double refraction_correction(double zenith) {
double exoatm_elevation = 90 - zenith;
if (exoatm_elevation > 85) {
return 0;
}
double refractionCorrection;
double te = tan(exoatm_elevation / RADEG);
if (exoatm_elevation > 5.0) {
refractionCorrection =
58.1 / te - 0.07 / (te * te * te) + 0.000086 / (te * te * te * te * te);
} else {
if (exoatm_elevation > -0.575) {
refractionCorrection = get_refraction_corrected_elevation(exoatm_elevation);
} else {
refractionCorrection = -20.774 / te;
}
}
return refractionCorrection / 3600;
}
double get_refraction_corrected_elevation(double e) {
return 1735.0 + e * (-518.2 + e * (103.4 + e * (-12.79 + e * 0.711)));
}
double solar_noon_time(double lon, double eqTime) {
return 720.0 + (lon * 4.0) - eqTime;
}
double sunrise_time(double lon, double eqTime, double ha, short timezone) {
return 720.0 + ((lon - ha) * 4.0) - eqTime + 60 * timezone;
}
double sunset_time(double lon, double eqTime, double ha, short timezone) {
return 720.0 + ((lon + ha) * 4.0) - eqTime + 60 * timezone;
}
double julian(double time) {
return (time / SEC_IN_DAY) + JULIAN_DAY_1970;
}
double sun_declination(double t) {
double e = obliquity_corrected(t) / RADEG;
double b = sun_apparent_longitude(t) / RADEG;
double sint = sin(e) * sin(b);
double theta = asin(sint);
return theta * RADEG;
}
double eccentricity_earth_orbit(double t) {
return 0.016708634 - t * (0.000042037 + 0.0000001267 * t);
}
double equation_of_time(double t) {
double eps = obliquity_corrected(t) / RADEG;
double l0 = sun_geometric_mean_longitude(t) / RADEG;
double m = sun_geometric_mean_anomaly(t) / RADEG;
double e = eccentricity_earth_orbit(t);
double y = tan(eps / 2);
y *= y;
double sin2l0 = sin(2 * l0);
double cos2l0 = cos(2 * l0);
double sin4l0 = sin(4 * l0);
double sin1m = sin(m);
double sin2m = sin(2 * m);
double etime =
y * sin2l0
- 2 * e * sin1m
+ 4 * e * y * sin1m * cos2l0
- 0.5 * y * y * sin4l0
- 1.25 * e * e * sin2m;
return (etime * RADEG) * 4.0;
}
double sun_geometric_mean_anomaly(double t) {
return 357.52911 + t * (35999.05029 - 0.0001537 * t);
}
double sun_equation_of_center(double t) {
double m = sun_geometric_mean_anomaly(t) / RADEG;
return sin(1 * m) * (1.914602 - t * (0.004817 + 0.000014 * t))
+ sin(2 * m) * (0.019993 - t * (0.000101))
+ sin(3 * m) * (0.000289);
}
double sun_geometric_mean_longitude(double t) {
double l0 = 280.46646 + t * (36000.76983 + 0.0003032 * t);
l0 = l0 - 360 * floor(l0 / 360);
return l0;
}
double sun_true_longitude(double t) {
return sun_geometric_mean_longitude(t) + sun_equation_of_center(t);
}
double sun_apparent_longitude(double t) {
double omega = (125.04 - 1934.136 * t) / RADEG;
return sun_true_longitude(t) - 0.00569 - 0.00478 * sin(omega);
}
double mean_obliquity_of_ecliptic(double t) {
double seconds = 21.448 - t * (46.8150 + t * (0.00059 - t * (0.001813)));
return 23.0 + (26.0 + (seconds / 60.0)) / 60.0;
}
double obliquity_corrected(double t) {
double e0 = mean_obliquity_of_ecliptic(t);
double omega = (125.04 - 1934.136 * t) / RADEG;
return e0 + 0.00256 * cos(omega);
}
public:
SolarThings(double longitude, double latitude) {
this->longitude = -longitude;
this->latitude = (latitude > 89.8) ? 89.8 : latitude;
this->latitude = (latitude < -89.8) ? -89.8 : this->latitude;
}
double elevation(long time) {
double julian_day = julian(time);
double mtime = (julian_day - 2451545) / 36525;
double solar_declin = sun_declination(mtime);
double eqTime = equation_of_time(mtime);
double trueSolarTime = ((julian_day + 0.5) - floor(julian_day + 0.5)) * 1440;
trueSolarTime += (eqTime - 4.0 * longitude);
trueSolarTime -= 1440 * floor(trueSolarTime / 1440);
double latitude_rad = this->latitude / RADEG;
double csz =
sin(latitude_rad) * sin(solar_declin / RADEG)
+ cos(latitude_rad)
* cos(solar_declin / RADEG)
* cos((trueSolarTime / 4 - 180) / RADEG);
if (csz > +1) csz = +1;
if (csz < -1) csz = -1;
double zenith = acos(csz);
double refractionCorrection = this->refraction_correction(zenith * RADEG);
double solarZen = (zenith * RADEG) - refractionCorrection;
double elevation = 90 - solarZen;
return elevation;
}
long sunrise(long time, short timezone) {
double julian_day = julian(time);
double mtime = (julian_day - 2451545) / 36525;
double solar_declin = sun_declination(mtime);
double eq_time = equation_of_time(mtime);
double latitude_rad = this->latitude / RADEG;
double ha = acos((cos(90.883 / RADEG)/(cos(latitude_rad) * cos(solar_declin / RADEG)))
- tan(latitude_rad) * tan(solar_declin / RADEG)) * RADEG;
long sunrise_timev = round(sunrise_time(longitude, eq_time, ha, timezone) * (60))
+ (time / SEC_IN_DAY) * SEC_IN_DAY;
return sunrise_timev;
}
long sunset(long time, short timezone) {
double julian_day = julian(time);
double mtime = (julian_day - 2451545) / 36525;
double solar_declin = sun_declination(mtime);
double eq_time = equation_of_time(mtime);
double latitude_rad = this->latitude / RADEG;
double ha = acos((cos(90.883 / RADEG)/(cos(latitude_rad) * cos(solar_declin / RADEG)))
- tan(latitude_rad) * tan(solar_declin / RADEG)) * RADEG;
long sunrise_timev = round(sunset_time(longitude, eq_time, ha, timezone) * (60))
+ (time / SEC_IN_DAY) * SEC_IN_DAY;
return sunrise_timev;
}
void celestial_bodies(long time, double (&result)[4]) {
double julian_day = julian(time);
double d = (julian_day - 2451545);
double w = 282.9404 + 4.70935E-5 * d;
double e = (0.016709 - (1.151E-9 * d));
double M = normalize(356.047 + 0.9856002585 * d);
double E = M + (180 / M_PI) * e * sin(M / RADEG) * (1 + e * cos(M / RADEG));
double xv = cos(E) - e;
double yv = sin(E) * sqrt(1 - e * e);
double r = sqrt(xv * xv + yv * yv);
double v = atan2(yv, xv) * RADEG;
double lonsun = normalize(v + w) / RADEG;
double xs = r * cos(lonsun);
double ys = r * sin(lonsun);
double earthX = -1 * xs;
double earthY = -1 * ys;
double N_moon = normalize(125.1228 - 0.0529538083 * d);
double i_moon = 5.1454;
double w_moon = 318.0634 + 0.1643573223 * d;
double a_moon = 60.2666 * 4.26354E-5;
double e_moon = 0.054900;
double M_moon = normalize(115.3654 + 13.0649929509 * d);
double moon_xy[2];
from_sun(M_moon, e_moon, a_moon, N_moon, w_moon, i_moon, moon_xy);
result[0] = earthX;
result[1] = earthY;
result[2] = moon_xy[0];
result[3] = moon_xy[1];
}
};