replace low_accuracy math functions (sint_t, cos_t, atan_t, ...) with standard libm functions that have higher accuracy.
This commit is contained in:
Frank 2023-09-30 23:34:02 +02:00
parent 5eadbe7ecd
commit 166316e0c5

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@ -412,8 +412,8 @@ int getSunriseUTC(int year, int month, int day, float lat, float lon, bool sunse
//1. first calculate the day of the year
float N1 = 275 * month / 9;
float N2 = (month + 9) / 12;
float N3 = (1 + floor_t((year - 4 * floor_t(year / 4) + 2) / 3));
float N = N1 - (N2 * N3) + day - 30;
float N3 = (1.0f + floorf((year - 4 * floorf(year / 4) + 2.0f) / 3.0f));
float N = N1 - (N2 * N3) + day - 30.0f;
//2. convert the longitude to hour value and calculate an approximate time
float lngHour = lon / 15.0f;
@ -423,37 +423,37 @@ int getSunriseUTC(int year, int month, int day, float lat, float lon, bool sunse
float M = (0.9856f * t) - 3.289f;
//4. calculate the Sun's true longitude
float L = fmod_t(M + (1.916f * sin_t(DEG_TO_RAD*M)) + (0.02f * sin_t(2*DEG_TO_RAD*M)) + 282.634f, 360.0f);
float L = fmodf(M + (1.916f * sinf(DEG_TO_RAD*M)) + (0.02f * sinf(2*DEG_TO_RAD*M)) + 282.634f, 360.0f);
//5a. calculate the Sun's right ascension
float RA = fmod_t(RAD_TO_DEG*atan_t(0.91764f * tan_t(DEG_TO_RAD*L)), 360.0f);
float RA = fmodf(RAD_TO_DEG*atan(0.91764f * tan(DEG_TO_RAD*L)), 360.0f);
//5b. right ascension value needs to be in the same quadrant as L
float Lquadrant = floor_t( L/90) * 90;
float RAquadrant = floor_t(RA/90) * 90;
float Lquadrant = floorf( L/90) * 90;
float RAquadrant = floorf(RA/90) * 90;
RA = RA + (Lquadrant - RAquadrant);
//5c. right ascension value needs to be converted into hours
RA /= 15.0f;
//6. calculate the Sun's declination
float sinDec = 0.39782f * sin_t(DEG_TO_RAD*L);
float cosDec = cos_t(asin_t(sinDec));
float sinDec = 0.39782f * sinf(DEG_TO_RAD*L);
float cosDec = cosf(asinf(sinDec));
//7a. calculate the Sun's local hour angle
float cosH = (sin_t(DEG_TO_RAD*ZENITH) - (sinDec * sin_t(DEG_TO_RAD*lat))) / (cosDec * cos_t(DEG_TO_RAD*lat));
if (cosH > 1 && !sunset) return 0; // the sun never rises on this location (on the specified date)
if (cosH < -1 && sunset) return 0; // the sun never sets on this location (on the specified date)
float cosH = (sinf(DEG_TO_RAD*ZENITH) - (sinDec * sinf(DEG_TO_RAD*lat))) / (cosDec * cosf(DEG_TO_RAD*lat));
if ((cosH > 1.0f) && !sunset) return 0; // the sun never rises on this location (on the specified date)
if ((cosH < -1.0f) && sunset) return 0; // the sun never sets on this location (on the specified date)
//7b. finish calculating H and convert into hours
float H = sunset ? RAD_TO_DEG*acos_t(cosH) : 360 - RAD_TO_DEG*acos_t(cosH);
float H = sunset ? RAD_TO_DEG*acosf(cosH) : 360 - RAD_TO_DEG*acosf(cosH);
H /= 15.0f;
//8. calculate local mean time of rising/setting
float T = H + RA - (0.06571f * t) - 6.622f;
//9. adjust back to UTC
float UT = fmod_t(T - lngHour, 24.0f);
float UT = fmodf(T - lngHour, 24.0f);
// return in minutes from midnight
return UT*60;