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Fix calculations for negative sun declination (#839)

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Fixes https://github.com/esphome/issues/issues/793

Also adds a clampd function that operates with doubles, not floats
This commit is contained in:
Otto Winter
2019-11-06 22:49:38 +01:00
parent 68a3b31628
commit 7f6672bb37
1 changed files with 11 additions and 3 deletions
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14
esphome/components/sun/sun.cpp
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@@ -52,6 +52,14 @@ double Sun::azimuth() {
return NAN;
return this->azimuth_(time);
}
// like clamp, but with doubles
double clampd(double val, double min, double max) {
if (val < min)
return min;
if (val > max)
return max;
return val;
}
double Sun::sun_declination_(double sun_time) {
double n = sun_time - 1.0;
// maximum declination
@@ -67,7 +75,7 @@ double Sun::sun_declination_(double sun_time) {
const double c = TAU / 365.24;
double v = cos(c * days_since_december_solstice + 2 * eccentricity * sin(c * days_since_perihelion));
// Make sure value is in range (double error may lead to results slightly larger than 1)
double x = clamp(tot * v, 0, 1);
double x = clampd(tot * v, -1.0, 1.0);
return asin(x);
}
double Sun::elevation_ratio_(double sun_time) {
@@ -75,7 +83,7 @@ double Sun::elevation_ratio_(double sun_time) {
double hangle = this->hour_angle_(sun_time);
double a = sin(this->latitude_rad_()) * sin(decl);
double b = cos(this->latitude_rad_()) * cos(decl) * cos(hangle);
double val = clamp(a + b, -1.0, 1.0);
double val = clampd(a + b, -1.0, 1.0);
return val;
}
double Sun::latitude_rad_() { return this->latitude_ * TO_RADIANS; }
@@ -92,7 +100,7 @@ double Sun::azimuth_rad_(double sun_time) {
double zen = this->zenith_rad_(sun_time);
double nom = cos(zen) * sin(this->latitude_rad_()) - sin(decl);
double denom = sin(zen) * cos(this->latitude_rad_());
double v = clamp(nom / denom, -1.0, 1.0);
double v = clampd(nom / denom, -1.0, 1.0);
double az = PI - acos(v);
if (hangle > 0)
az = -az;