💿🐜 Antkeeper source code https://antkeeper.com
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  1. /*
  2. * Copyright (C) 2021 Christopher J. Howard
  3. *
  4. * This file is part of Antkeeper source code.
  5. *
  6. * Antkeeper source code is free software: you can redistribute it and/or modify
  7. * it under the terms of the GNU General Public License as published by
  8. * the Free Software Foundation, either version 3 of the License, or
  9. * (at your option) any later version.
  10. *
  11. * Antkeeper source code is distributed in the hope that it will be useful,
  12. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14. * GNU General Public License for more details.
  15. *
  16. * You should have received a copy of the GNU General Public License
  17. * along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
  18. */
  19. #ifndef ANTKEEPER_PHYSICS_TIME_UT1_HPP
  20. #define ANTKEEPER_PHYSICS_TIME_UT1_HPP
  21. #include "math/constants.hpp"
  22. namespace physics {
  23. namespace time {
  24. /// Functions which operate on UT1 universal time.
  25. namespace ut1 {
  26. /**
  27. * Calculates the Earth Rotation Angle (ERA) at a given UT1 date.
  28. *
  29. * @param t J2000 UT1 date.
  30. * @return ERA at the given date, in radians.
  31. */
  32. template <class T>
  33. T era(T t);
  34. template <class T>
  35. T era(T t)
  36. {
  37. return math::two_pi<T> * (T(0.7790572732640) + T(1.00273781191135448) * t);
  38. }
  39. } // namespace ut1
  40. } // namespace time
  41. } // namespace physics
  42. #endif // ANTKEEPER_PHYSICS_TIME_UT1_HPP