Added 2 points distance on sphere function.

Math/Shape/D3/Sphere.php

@@ -0,0 +1,54 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.0
+ *
+ * @category   TBD
+ * @package    TBD
+ * @author     OMS Development Team <dev@oms.com>
+ * @author     Dennis Eichhorn <d.eichhorn@oms.com>
+ * @copyright  2013 Dennis Eichhorn
+ * @license    OMS License 1.0
+ * @version    1.0.0
+ * @link       http://orange-management.com
+ */
+namespace phpOMS\Math\Algebra;
+
+class Sphere
+{
+
+    /**
+     * Calculating the distance between two points on a sphere
+     *
+     * @param float $latStart  Latitude of start point in deg
+     * @param float $longStart Longitude of start point in deg
+     * @param float $latEnd    Latitude of target point in deg
+     * @param float $longEnd   Longitude of target point in deg
+     * @param float $radius    Sphere radius
+     *
+     * @return float Distance between points in meter
+     *
+     * @since  1.0.0
+     * @author Dennis Eichhorn <d.eichhorn@oms.com>
+     */
+    public static function distance2PointsOnSphere(\float $latStart, \float $longStart, \float $latEnd, \float $longEnd, \float $radius = 6371000.0) : \float
+    {
+        $latFrom = deg2rad($latStart);
+        $lonFrom = deg2rad($longStart);
+        $latTo   = deg2rad($latEnd);
+        $lonTo   = deg2rad($longEnd);
+
+        $latDelta = $latTo - $latFrom;
+        $lonDelta = $lonTo - $lonFrom;
+
+        $a        = pow(cos($latTo) * sin($lonDelta), 2) + pow(cos($latFrom) * sin($latTo) - sin($latFrom) * cos($latTo) * cos($lonDelta), 2);
+        $b        = sin($latFrom) * sin($latTo) + cos($latFrom) * cos($latTo) * cos($lonDelta);
+
+        $angle = atan2(sqrt($a), $b);
+        // Approximation (very good for short distances)
+        // $angle = 2 * asin(sqrt(pow(sin($latDelta / 2), 2) + cos($latFrom) * cos($latTo) * pow(sin($lonDelta / 2), 2)));
+
+        return $angle * $radius;
+    }
+}