/**
* Copyright © 2016 Mattias Andrée <maandree@member.fsf.org>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
/**
* Approximate apparent size of the Sun in degrees.
*/
#define SOLAR_APPARENT_RADIUS (32.0 / 60.0)
/**
* The Sun's elevation at sunset and sunrise, measured in degrees.
*/
#define SOLAR_ELEVATION_SUNSET_SUNRISE (0.0)
/**
* The Sun's elevation at civil dusk and civil dawn, measured in degrees.
*/
#define SOLAR_ELEVATION_CIVIL_DUSK_DAWN (-6.0)
/**
* The Sun's elevation at nautical dusk and nautical dawn, measured in degrees.
*/
#define SOLAR_ELEVATION_NAUTICAL_DUSK_DAWN (-12.0)
/**
* The Sun's elevation at astronomical dusk and astronomical dawn, measured in degrees.
*/
#define SOLAR_ELEVATION_ASTRONOMICAL_DUSK_DAWN (-18.0)
/**
* Test whether it is twilight.
*
* @param ELEV:double The current elevation.
* @return 1 if is twilight, 0 otherwise.
*/
#define SOLAR_IS_TWILIGHT(ELEV) ((-18.0 <= (ELEV)) && ((ELEV) <= 0.0))
/**
* Test whether it is civil twilight.
*
* @param ELEV:double The current elevation.
* @return 1 if is civil twilight, 0 otherwise.
*/
#define SOLAR_IS_CIVIL_TWILIGHT(ELEV) ((-6.0 <= (ELEV)) && ((ELEV) <= 0.0))
/**
* Test whether it is nautical twilight.
*
* @param ELEV:double The current elevation.
* @return 1 if is nautical twilight, 0 otherwise.
*/
#define SOLAR_IS_NAUTICAL_TWILIGHT(ELEV) ((-12.0 <= (ELEV)) && ((ELEV) <= -6.0))
/**
* Test whether it is astronomical twilight.
*
* @param ELEV:double The current elevation.
* @return 1 if is astronomical twilight, 0 otherwise.
*/
#define SOLAR_IS_ASTRONOMICAL_TWILIGHT(ELEV) ((-18.0 <= (ELEV)) && ((ELEV) <= -12.0))
/**
* 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 solar_elevation(double latitude, double longitude);
