Sunclock.hpp

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#ifndef DAYLIGHT_SUNCLOCK_HPP
#define DAYLIGHT_SUNCLOCK_HPP

#include <ctime>

class Sunclock {
public:
  Sunclock(double const &latitude_, double const &longitude_, double const &tz_offset_ = 0);

  double irradiance();

  double irradiance(time_t when);

  time_t sunrise();

  time_t sunrise(time_t date);

  time_t solar_noon();

  time_t solar_noon(time_t date);

  time_t sunset();

  time_t sunset(time_t date);

private:
  // in decimal degrees, east is positive
  double const latitude;

  // in decimal degrees, north is positive
  double const longitude;

  // in hours, east is positive, i.e. IST (+05:30) is 5.5
  double const tz_offset;

  double time_of_day(time_t date);

  static int days_since_1900(struct tm *t);

  static time_t time_from_decimal_day(time_t date, double decimal_day);

  static double julian_day(struct tm *t, double const &time_of_day, double const &timezone);

  void prepare_time(time_t const &when, struct tm *ptm);

  double julian_century(double _julian_day);
  double mean_long_sun(double _julian_century);
  double mean_anom_sun(double _julian_century);
  double sun_eq_of_centre(double _mean_anom_sun, double _julian_century);
  double eccent_earth_orbit(double _julian_century);
  double var_y(double _obliq_corr);
  double mean_obliq_ecliptic(double _julian_century);
  double sun_true_long(double _mean_long_sun, double _sun_eq_of_centre);
  double obliq_corr(double _mean_obliq_ecliptic, double _julian_century);
  double sun_app_long(double _sun_true_long, double _julian_century);
  double declination(double _obliq_corr, double _sun_app_long);
  double eq_of_time(double _var_y, double _mean_long_sun, double _eccent_earth_orbit,
                    double _mean_anom_sun);
  double true_solar_time(double _time_of_day, double _eq_of_time);
  double hour_angle(double _true_solar_time);
  double hour_angle_sunrise(double _declination);
  double solar_zenith(double _declination, double _hour_angle);
  double solar_elevation(double _solar_zenith);
};

#endif