From b0f210db18e12d4173a492552a83f8bcf10bfaad Mon Sep 17 00:00:00 2001
From: Bigeon Emmanuel <bigeon@irif.fr>
Date: Wed, 14 Feb 2024 14:17:43 +0100
Subject: [PATCH] [tool] GPS computer

---
 .../fr/u_paris/gla/project/utils/GPS.java     | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 src/main/java/fr/u_paris/gla/project/utils/GPS.java

diff --git a/src/main/java/fr/u_paris/gla/project/utils/GPS.java b/src/main/java/fr/u_paris/gla/project/utils/GPS.java
new file mode 100644
index 0000000..1aaca79
--- /dev/null
+++ b/src/main/java/fr/u_paris/gla/project/utils/GPS.java
@@ -0,0 +1,43 @@
+/**
+ * 
+ */
+package fr.u_paris.gla.project.utils;
+
+/** A utility class for computations related to GPS.
+ * 
+ * @author Emmanuel Bigeon */
+public final class GPS {
+
+    /** The (approximated) earth radius in km. */
+    private static final double EARTH_RADIUS = 6_370.0;
+
+    /** Hidden constructor for tool class */
+    private GPS() {
+        // Tool class
+    }
+
+    /** Convert a degree angle value in a radian angle one.
+     * 
+     * @param degree the degree value
+     * @return the radian value */
+    private static final double degreeToRadian(double degree) {
+        return degree / 180 * Math.PI;
+    }
+
+    /** Compute the flying distance between two GPS positions.
+     * 
+     * @param latitude1 the latitude of the first position
+     * @param longitude1 the longitude of the first position
+     * @param latitude2 the latitude of the second position
+     * @param longitude2 the longitude of the second position
+     * @return the flying distance */
+    public static double distance(double latitude1, double longitude1, double latitude2,
+            double longitude2) {
+        double deltaLatitude = degreeToRadian(latitude2 - latitude1);
+        double deltaLongitude = degreeToRadian(longitude2 - longitude1);
+        double a = Math.pow(Math.sin(deltaLatitude / 2), 2)
+                + Math.pow(Math.sin(deltaLongitude), 2) * Math.cos(latitude1)
+                        * Math.cos(latitude2);
+        return EARTH_RADIUS * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
+    }
+}