Merge pull request #91 from WimDeMeester/master

Fixes for equation of time

changelog.md

@@ -2,6 +2,13 @@
 
 All notable changes to `laravel-astronomy-library` will be documented in this file.
 
+## Version 6.2
+
+Changed:
+
+- Fix equation of time for March 21 and 22. 
+- Return equation of time as float and not as CarbonInterval (which fails for negative values).
+
 ## Version 6.1.2
 
 Changed:

src/deepskylog/AstronomyLibrary/Targets/Sun.php

@@ -16,7 +16,6 @@
 namespace deepskylog\AstronomyLibrary\Targets;
 
 use Carbon\Carbon;
-use Carbon\CarbonInterval;
 use deepskylog\AstronomyLibrary\Coordinates\Coordinate;
 use deepskylog\AstronomyLibrary\Coordinates\EclipticalCoordinates;
 use deepskylog\AstronomyLibrary\Coordinates\EquatorialCoordinates;
@@ -715,11 +714,11 @@ public function calculateGeometricCoordinatesJ2000(Carbon $date): RectangularCoo
      * Calculates the equation of time of the sun for a given date.
      *
      * @param  Carbon  $date  The date
-     * @return CarbonInterval The equation of time
+     * @return float The equation of time in minutes
      *
      * See chapter 28 of Astronomical Algorithms
      */
-    public function calculateEquationOfTime(Carbon $date): CarbonInterval
+    public function calculateEquationOfTime(Carbon $date): float
     {
         $tau = (Time::getJd($date) - 2451545.0) / 365250.0;
 
@@ -734,7 +733,11 @@ public function calculateEquationOfTime(Carbon $date): CarbonInterval
 
         $E = $L0->getCoordinate() - 0.0057183 - $ra + $nutation[0] / 3600.0 * cos(deg2rad($nutation[3]));
 
-        return CarbonInterval::make($E * 4 .'m');
+        if ($E > 180) {
+            $E = $E - 360;
+        }
+
+        return $E * 4;
     }
 
     /**

tests/Unit/SunTest.php

@@ -16,7 +16,6 @@
 namespace Tests\Unit;
 
 use Carbon\Carbon;
-use Carbon\CarbonInterval;
 use deepskylog\AstronomyLibrary\Targets\Sun;
 use deepskylog\AstronomyLibrary\Testing\BaseTestCase;
 use deepskylog\AstronomyLibrary\Time;
@@ -120,7 +119,7 @@ public function testEquationOfTime()
 
         $equationOfTime = $sun->calculateEquationOfTime($date);
 
-        $this->assertEquals(CarbonInterval::create(0, 0, 0, 0, 0, 13, 42, 564279), $equationOfTime);
+        $this->assertEquals(13.7090, $equationOfTime);
     }
 
     public function testPhysicalEphemeris()