fix true anomaly for 0 inclination and 0 eccentricity

jordanstephens · Jul 20, 2015 · 9067878 · 9067878
1 parent c514e87
commit 9067878
Showing 1 changed file with 13 additions and 2 deletions.
diff --git a/lib/orbit.js b/lib/orbit.js
@@ -82,8 +82,19 @@ Orbit.prototype.argumentOfPeriapsis = function argumentOfPeriapsis() {
 };
 
 Orbit.prototype.trueAnomaly = function trueAnomaly() {
-  var e = this.eccentricity();
-  var u = toDeg(Math.acos(Math.min(1, e.dot(this.r) / (e.norm() * this.r.norm()))));
+  var e = this.eccentricity(),
+      eNorm = parseFloat(e.norm().toFixed(5)),
+      n = this.nodeLine(),
+      nNorm = parseFloat(e.norm().toFixed(5)),
+      l, u;
+
+  if (eNorm === 0 && nNorm === 0) {
+    u = toDeg(Math.acos(Math.min(1, this.r.elements[0] / this.r.norm())));
+  } else {
+    l = (eNorm === 0) ? n : e;
+    u = toDeg(Math.acos(Math.min(1, l.dot(this.r) / (l.norm() * this.r.norm()))));
+  }
+
   return this.r.dot(this.v) < 0 ? (360 - u) : u;
 };