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#include <math.h>
#include <glib.h>
#define PI 3.1415926
#define ZENITH -.83
float calculateSunrise(int year,int month,int day,float lat, float lng,int localOffset) {
/*
localOffset will be <0 for western hemisphere and >0 for eastern hemisphere
daylightSavings should be 1 if it is in effect during the summer otherwise it should be 0
*/
//1. first calculate the day of the year
float N1 = floor(275 * month / 9);
float N2 = floor((month + 9) / 12);
float N3 = (1 + floor((year - 4 * floor(year / 4) + 2) / 3));
float N = N1 - (N2 * N3) + day - 30;
//2. convert the longitude to hour value and calculate an approximate time
float lngHour = lng / 15.0;
float t = N + ((6 - lngHour) / 24);
//3. calculate the Sun's mean anomaly
float M = (0.9856 * t) - 3.289;
//4. calculate the Sun's true longitude
float L = fmod(M + (1.916 * sin((PI/180)*M)) + (0.020 * sin(2 *(PI/180) * M)) + 282.634,360.0);
if ( L < 0 )
L = L+360;
else if ( L > 360)
L = L-360;
//5a. calculate the Sun's right ascension
float RA = fmod(180/PI*atan(0.91764 * tan((PI/180)*L)),360.0);
if ( RA < 0 )
RA = RA+360;
else if ( RA > 360)
RA = RA-360;
//5b. right ascension value needs to be in the same quadrant as L
float Lquadrant = floor( L/90) * 90;
float RAquadrant = floor(RA/90) * 90;
RA = RA + (Lquadrant - RAquadrant);
//5c. right ascension value needs to be converted into hours
RA = RA / 15;
//6. calculate the Sun's declination
float sinDec = 0.39782 * sin((PI/180)*L);
float cosDec = cos(asin(sinDec));
//7a. calculate the Sun's local hour angle
float cosH = (sin((PI/180)*ZENITH) - (sinDec * sin((PI/180)*lat))) / (cosDec * cos((PI/180)*lat));
if (cosH > 1)
g_print("Never rising\n");
else if (cosH < -1)
g_print("Never setting\n");
//7b. finish calculating H and convert into hours
float H = 360 - (180/PI)*acos(cosH); // if if rising time is desired:
H = H / 15;
//8. calculate local mean time of rising/setting
float T = H + RA - (0.06571 * t) - 6.622;
//9. adjust back to UTC
float UT = fmod(T - lngHour,24.0);
if ( UT < 0 )
UT = UT+24;
else if (UT > 24)
UT = UT-24;
//10. convert UT value to local time zone of latitude/longitude
return UT + localOffset;
}
float calculateSunset(int year,int month,int day,float lat, float lng,int localOffset) {
/*
localOffset will be <0 for western hemisphere and >0 for eastern hemisphere
daylightSavings should be 1 if it is in effect during the summer otherwise it should be 0
*/
//1. first calculate the day of the year
float N1 = floor(275 * month / 9);
float N2 = floor((month + 9) / 12);
float N3 = (1 + floor((year - 4 * floor(year / 4) + 2) / 3));
float N = N1 - (N2 * N3) + day - 30;
//2. convert the longitude to hour value and calculate an approximate time
float lngHour = lng / 15.0;
float t = N + ((18 - lngHour) / 24); //if setting time is desired:
//3. calculate the Sun's mean anomaly
float M = (0.9856 * t) - 3.289;
//4. calculate the Sun's true longitude
float L = fmod(M + (1.916 * sin((PI/180)*M)) + (0.020 * sin(2 *(PI/180) * M)) + 282.634,360.0);
if ( L < 0 )
L = L+360;
else if ( L > 360)
L = L-360;
//5a. calculate the Sun's right ascension
float RA = fmod(180/PI*atan(0.91764 * tan((PI/180)*L)),360.0);
if ( RA < 0 )
RA = RA+360;
else if ( RA > 360)
RA = RA-360;
//5b. right ascension value needs to be in the same quadrant as L
float Lquadrant = floor( L/90) * 90;
float RAquadrant = floor(RA/90) * 90;
RA = RA + (Lquadrant - RAquadrant);
//5c. right ascension value needs to be converted into hours
RA = RA / 15;
//6. calculate the Sun's declination
float sinDec = 0.39782 * sin((PI/180)*L);
float cosDec = cos(asin(sinDec));
//7a. calculate the Sun's local hour angle
float cosH = (sin((PI/180)*ZENITH) - (sinDec * sin((PI/180)*lat))) / (cosDec * cos((PI/180)*lat));
if (cosH > 1)
g_print("Never rising\n");
else if (cosH < -1)
g_print("Never setting\n");
//7b. finish calculating H and convert into hours
float H = (180/PI)*acos(cosH); // if setting time is desired:
H = H / 15;
//8. calculate local mean time of rising/setting
float T = H + RA - (0.06571 * t) - 6.622;
//9. adjust back to UTC
float UT = fmod(T - lngHour,24.0);
if ( UT < 0 )
UT = UT+24;
else if (UT > 24)
UT = UT-24;
//10. convert UT value to local time zone of latitude/longitude
return UT + localOffset;
}
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