Merge branch 'master' of github.com:manuelbieh/geolib

manuelbieh · Jun 23, 2019 · 6c72bd0 · 6c72bd0
2 parents 0a55d4b + 46590b0
commit 6c72bd0
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Showing 2 changed files with 18 additions and 20 deletions.
diff --git a/src/getDistance.test.js b/src/getDistance.test.js
@@ -1,14 +1,5 @@
 import getDistance from './getDistance';
 
-// Icecream for the first person who can tell me why this is NaN:
-// console.log(
-//     'distance:',
-//     getDistance(
-//         { latitude: 51.516241842, longitude: 7.456494328 },
-//         { latitude: 51.516241842, longitude: 7.456494328 }
-//     )
-// );
-
 describe('getDistance', () => {
     it('should calculate the distance between any two points', () => {
         expect(
@@ -46,12 +37,11 @@ describe('getDistance', () => {
             )
         ).toBe(0);
 
-        // TODO: WTF! Why is this NaN?!
-        // expect(
-        //     getDistance(
-        //         { latitude: 51.516241842, longitude: 7.456494328 },
-        //         { latitude: 51.516241842, longitude: 7.456494328 }
-        //     )
-        // ).toBe(0);
+        expect(
+            getDistance(
+                { latitude: 51.516241842, longitude: 7.456494328 },
+                { latitude: 51.516241842, longitude: 7.456494328 }
+            )
+        ).toBe(0);
     });
 });
diff --git a/src/getDistance.ts b/src/getDistance.ts
@@ -4,6 +4,12 @@ import toRad from './toRad';
 import { earthRadius } from './constants';
 import { GeolibInputCoordinates } from './types';
 
+const normalizeACosArg = (val: number): number => {
+    if (val > 1) return 1;
+    if (val < -1) return -1;
+    return val;
+};
+
 // Calculates the distance between two points.
 // This method is simple but also more inaccurate
 const getDistance = (
@@ -21,10 +27,12 @@ const getDistance = (
 
     const distance =
         Math.acos(
-            Math.sin(toRad(toLat)) * Math.sin(toRad(fromLat)) +
-                Math.cos(toRad(toLat)) *
-                    Math.cos(toRad(fromLat)) *
-                    Math.cos(toRad(fromLon) - toRad(toLon))
+            normalizeACosArg(
+                Math.sin(toRad(toLat)) * Math.sin(toRad(fromLat)) +
+                    Math.cos(toRad(toLat)) *
+                        Math.cos(toRad(fromLat)) *
+                        Math.cos(toRad(fromLon) - toRad(toLon))
+            )
         ) * earthRadius;
 
     return Math.round(distance / accuracy) * accuracy;