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author | Mattias Andrée <maandree@kth.se> | 2019-10-06 09:36:23 +0200 |
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committer | Mattias Andrée <maandree@kth.se> | 2019-10-06 09:36:23 +0200 |
commit | 1be48c64b4e5df9e9b1ad69b3bb30b867b0abf9e (patch) | |
tree | 697f6c2fb5f3f91ab64e6ed32c45e483bf31e442 /src/solar.c | |
parent | Add golden hour and blue hour (diff) | |
download | libred-1be48c64b4e5df9e9b1ad69b3bb30b867b0abf9e.tar.gz libred-1be48c64b4e5df9e9b1ad69b3bb30b867b0abf9e.tar.bz2 libred-1be48c64b4e5df9e9b1ad69b3bb30b867b0abf9e.tar.xz |
Clean up
Signed-off-by: Mattias Andrée <maandree@kth.se>
Diffstat (limited to 'src/solar.c')
-rw-r--r-- | src/solar.c | 314 |
1 files changed, 0 insertions, 314 deletions
diff --git a/src/solar.c b/src/solar.c deleted file mode 100644 index de229d9..0000000 --- a/src/solar.c +++ /dev/null @@ -1,314 +0,0 @@ -/** - * Copyright © 2016 Mattias Andrée <maandree@member.fsf.org> - * - * This program is free software: you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation, either version 3 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program. If not, see <http://www.gnu.org/licenses/>. - * - * This file is a stripped down port of <https://github.com/maandree/solar-python>. - */ -#include "libred.h" -#include <math.h> -#include <time.h> -#include <errno.h> -#include <stdio.h> -#include <stdlib.h> - -#if __GNUC__ -# pragma GCC diagnostic push -# pragma GCC diagnostic ignored "-Wunsuffixed-float-constants" -#endif - - - -/* Select clock. */ -#if defined(DO_NOT_USE_COARSEC_CLOCK) || !defined(CLOCK_REALTIME_COARSE) -# ifdef CLOCK_REALTIME_COARSE -# undef CLOCK_REALTIME_COARSE -# endif -# define CLOCK_REALTIME_COARSE CLOCK_REALTIME -#endif - - - -/** - * Get current Julian Centuries time (100 Julian days since J2000.) - * - * @return The current Julian Centuries time. - * - * @throws 0 On success. - * @throws Any error specified for clock_gettime(3) on error. - */ -static double julian_centuries() -{ - struct timespec now; - double tm; - if (clock_gettime(CLOCK_REALTIME_COARSE, &now)) return 0.0; - tm = (double)(now.tv_nsec) / 1000000000.0 + (double)(now.tv_sec); - tm = (tm / 86400.0 + 2440587.5 - 2451545.0) / 36525.0; - return errno = 0, tm; -} - -/** - * Convert a Julian Centuries timestamp to a Julian Day timestamp. - * - * @param tm The time in Julian Centuries - * @return The time in Julian Days - */ -static inline double julian_centuries_to_julian_day(double tm) -{ - return tm * 36525.0 + 2451545.0; -} - - -/** - * Convert an angle (or otherwise) from degrees to radians. - * - * @param deg The angle in degrees. - * @param The angle in radians. - */ -static inline double radians(double deg) -{ - return deg * (double)M_PI / 180.0; -} - -/** - * Convert an angle (or otherwise) from radians to degrees. - * - * @param rad The angle in radians. - * @param The angle in degrees. - */ -static inline double degrees(double rad) -{ - return rad * 180.0 / (double)M_PI; -} - - -/** - * Calculates the Sun's elevation from the solar hour angle - * - * @param longitude The longitude in degrees eastwards. - * from Greenwich, negative for westwards. - * @param declination The declination, in radians. - * @param hour_angle The solar hour angle, in radians. - * @return The Sun's elevation, in radians. - */ -static inline double elevation_from_hour_angle(double latitude, double declination, double hour_angle) -{ - double rc = cos(radians(latitude)); - rc *= cos(hour_angle) * cos(declination); - rc += sin(radians(latitude)) * sin(declination); - return asin(rc); -} - -/** - * Calculates the Sun's geometric mean longitude. - * - * @param tm The time in Julian Centuries. - * @return The Sun's geometric mean longitude in radians. - */ -static inline double sun_geometric_mean_longitude(double tm) -{ - double rc = fmod(pow(0.0003032 * tm, 2.0) + 36000.76983 * tm + 280.46646, 360.0); -#if defined(TIMETRAVELLER) - rc = rc < 0.0 ? (rc + 360.0) : rc; -#endif - return radians(rc); -} - -/** - * Calculates the Sun's geometric mean anomaly. - * - * @param tm The time in Julian Centuries. - * @return The Sun's geometric mean anomaly in radians. - */ -static inline double sun_geometric_mean_anomaly(double tm) -{ - return radians(pow(-0.0001537 * tm, 2.0) + 35999.05029 * tm + 357.52911); -} - -/** - * Calculates the Earth's orbit eccentricity. - * - * @param tm The time in Julian Centuries. - * @return The Earth's orbit eccentricity. - */ -static inline double earth_orbit_eccentricity(double tm) -{ - return pow(-0.0000001267 * tm, 2.0) - 0.000042037 * tm + 0.016708634; -} - -/** - * Calculates the Sun's equation of the centre, the difference - * between the true anomaly and the mean anomaly. - * - * @param tm The time in Julian Centuries. - * @return The Sun's equation of the centre, in radians. - */ -static inline double sun_equation_of_centre(double tm) -{ - double a = sun_geometric_mean_anomaly(tm), rc; - rc = sin(1.0 * a) * (pow(-0.000014 * tm, 2.0) - 0.004817 * tm + 1.914602); - rc += sin(2.0 * a) * (-0.000101 * tm + 0.019993); - rc += sin(3.0 * a) * 0.000289; - return radians(rc); -} - -/** - * Calculates the Sun's real longitudinal position. - * - * @param tm The time in Julian Centuries. - * @return The longitude, in radians. - */ -static inline double sun_real_longitude(double tm) -{ - return sun_geometric_mean_longitude(tm) + sun_equation_of_centre(tm); -} - -/** - * Calculates the Sun's apparent longitudinal position. - * - * @param tm The time in Julian Centuries. - * @return The longitude, in radians. - */ -static inline double sun_apparent_longitude(double tm) -{ - double rc = degrees(sun_real_longitude(tm)) - 0.00569; - return radians(rc - 0.00478 * sin(radians(-1934.136 * tm + 125.04))); -} - -/** - * Calculates the mean ecliptic obliquity of the Sun's - * apparent motion without variation correction. - * - * @param tm The time in Julian Centuries. - * @return The uncorrected mean obliquity, in radians. - */ -static double mean_ecliptic_obliquity(double tm) -{ - double rc = pow(0.001813 * tm, 3.0) - pow(0.00059 * tm, 2.0) - 46.815 * tm + 21.448; - return radians(23.0 + (26.0 + rc / 60.0) / 60.0); -} - -/** - * Calculates the mean ecliptic obliquity of the Sun's - * parent motion with variation correction. - * - * @param tm The time in Julian Centuries. - * @return The mean obliquity, in radians. - */ -static double corrected_mean_ecliptic_obliquity(double tm) -{ - double rc = 0.00256 * cos(radians(-1934.136 * tm + 125.04)); - return radians(rc + degrees(mean_ecliptic_obliquity(tm))); -} - -/** - * Calculates the Sun's declination. - * - * @param tm The time in Julian Centuries. - * @return The Sun's declination, in radian. - */ -static inline double solar_declination(double tm) -{ - double rc = sin(corrected_mean_ecliptic_obliquity(tm)); - return asin(rc * sin(sun_apparent_longitude(tm))); -} - -/** - * Calculates the equation of time, the discrepancy - * between apparent and mean solar time. - * - * @param tm The time in Julian Centuries. - * @return The equation of time, in degrees. - */ -static inline double equation_of_time(double tm) -{ - double l = sun_geometric_mean_longitude(tm); - double e = earth_orbit_eccentricity(tm); - double m = sun_geometric_mean_anomaly(tm); - double y = pow(tan(corrected_mean_ecliptic_obliquity(tm) / 2.0), 2.0); - double rc = y * sin(2.0 * l); - rc += (4.0 * y * cos(2.0 * l) - 2.0) * e * sin(m); - rc -= pow(0.5 * y, 2.0) * sin(4.0 * l); - rc -= pow(1.25 * e, 2.0) * sin(2.0 * m); - return 4.0 * degrees(rc); -} - -/** - * Calculates the Sun's elevation as apparent - * from a geographical position. - * - * @param tm The time in Julian Centuries. - * @param latitude The latitude in degrees northwards from - * the equator, negative for southwards. - * @param longitude The longitude in degrees eastwards from - * Greenwich, negative for westwards. - * @return The Sun's apparent elevation at the specified time as seen - * from the specified position, measured in radians. - */ -static inline double solar_elevation_from_time(double tm, double latitude, double longitude) -{ - double rc = julian_centuries_to_julian_day(tm); - rc = (rc - round(rc) - 0.5) * 1440; - rc = 720.0 - rc - equation_of_time(tm); - rc = radians(rc / 4.0 - longitude); - return elevation_from_hour_angle(latitude, solar_declination(tm), rc); -} - - -/** - * Calculates the Sun's elevation as apparent - * from a geographical position. - * - * @param latitude The latitude in degrees northwards from - * the equator, negative for southwards. - * @param longitude The longitude in degrees eastwards from - * Greenwich, negative for westwards. - * @return The Sun's apparent elevation as seen, right now, - * from the specified position, measured in degrees. - * - * @throws 0 On success. - * @throws Any error specified for clock_gettime(3) on error. - */ -double libred_solar_elevation(double latitude, double longitude) -{ - double tm = julian_centuries(); - return errno ? -1 : degrees(solar_elevation_from_time(tm, latitude, longitude)); -} - - -/** - * Exit if time the is before year 0 in J2000. - * - * @return 0 on success, -1 on error. - */ -int libred_check_timetravel(void) -{ -#if !defined(TIMETRAVELLER) - struct timespec now; - if (clock_gettime(CLOCK_REALTIME, &now)) return -1; - if (now.tv_nsec < (time_t)946728000L) - fprintf(stderr, - "We have detected that you are a time-traveller" - "(or your clock is not configured correctly.)" - "Please recompile libred with -DTIMETRAVELLER" - "(or correct your clock.)"), exit(1); -#endif - return 0; -} - - -#if __GNUC__ -# pragma GCC diagnostic pop -#endif - |