From 919d809467739c9c4df832a363f35fd87af575bb Mon Sep 17 00:00:00 2001
From: Cat Flynn <me@ktyl.dev>
Date: Sat, 28 Sep 2024 20:15:29 +0100
Subject: [PATCH] fix: avoid singularities

---
 lib/skein/include/skein/orbit.h | 1 +
 lib/skein/src/orbit.cpp         | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/lib/skein/include/skein/orbit.h b/lib/skein/include/skein/orbit.h
index 1aa1c8c..377dd3c 100644
--- a/lib/skein/include/skein/orbit.h
+++ b/lib/skein/include/skein/orbit.h
@@ -53,4 +53,5 @@ private:
     double _meanAnomalyAtEpoch = 0;
 
     const double getEccentricAnomaly() const;
+    static void makeSafe(double& value);
 };
diff --git a/lib/skein/src/orbit.cpp b/lib/skein/src/orbit.cpp
index 97224b5..594ffa2 100644
--- a/lib/skein/src/orbit.cpp
+++ b/lib/skein/src/orbit.cpp
@@ -11,6 +11,12 @@ Orbit::Orbit()
     _keplerianElements.resize(6);
 }
 
+// some values cause singularities when they are zero. so, make them not zero
+void Orbit::makeSafe(double& value)
+{
+    value = value == 0.0 ? 0.0000001 : value;
+}
+
 double Orbit::getSemiMajorAxis() const
 {
     return _keplerianElements[astro::semiMajorAxisIndex];
@@ -35,6 +41,7 @@ double Orbit::getInclination() const
 }
 void Orbit::setInclination(double inclination)
 {
+    makeSafe(inclination);
     _keplerianElements[astro::inclinationIndex] = inclination;
 }
 
@@ -44,6 +51,7 @@ double Orbit::getArgumentOfPeriapsis() const
 }
 void Orbit::setArgumentOfPeriapsis(double argumentOfPeriapsis)
 {
+    makeSafe(argumentOfPeriapsis);
     _keplerianElements[astro::argumentOfPeriapsisIndex] = argumentOfPeriapsis;
 }
 
@@ -53,6 +61,7 @@ double Orbit::getLongitudeOfAscendingNode() const
 }
 void Orbit::setLongitudeOfAscendingNode(double longitudeOfAscendingNode)
 {
+    makeSafe(longitudeOfAscendingNode);
     _keplerianElements[astro::longitudeOfAscendingNodeIndex] = longitudeOfAscendingNode;
 }