Merge remote-tracking branch 'forkLouis/Issue-786' into pre-release

src/main/java/org/orekit/orbits/Orbit.java

@@ -163,23 +163,26 @@ public abstract class Orbit
      */
     protected static boolean hasNonKeplerianAcceleration(final PVCoordinates pva, final double mu) {
 
-        final Vector3D a = pva.getAcceleration();
-        if (a == null) {
-            return false;
-        }
-
         final Vector3D p = pva.getPosition();
         final double r2 = p.getNormSq();
         final double r  = FastMath.sqrt(r2);
         final Vector3D keplerianAcceleration = new Vector3D(-mu / (r * r2), p);
-        if (a.getNorm() > 1.0e-9 * keplerianAcceleration.getNorm()) {
+
+        // Check if acceleration is null or relatively close to 0 compared to the keplerain acceleration
+        final Vector3D a = pva.getAcceleration();
+        if (a == null || a.getNorm() < 1e-9 * keplerianAcceleration.getNorm()) {
+            return false;
+        }
+
+        final Vector3D nonKeplerianAcceleration = a.subtract(keplerianAcceleration);
+
+        if ( nonKeplerianAcceleration.getNorm() > 1e-9 * keplerianAcceleration.getNorm()) {
             // we have a relevant acceleration, we can compute derivatives
             return true;
         } else {
             // the provided acceleration is either too small to be reliable (probably even 0), or NaN
             return false;
         }
-
     }
 
     /** Get the orbit type.

src/test/java/org/orekit/orbits/FieldCartesianOrbitTest.java

@@ -599,9 +599,8 @@ public class FieldCartesianOrbitTest {
         FieldVector3D<T> velocity = new FieldVector3D<>(zero.add(-500.0), zero.add(8000.0), zero.add(1000.0));
         T r2 = position.getNormSq();
         T r = r2.sqrt();
-        FieldPVCoordinates<T> pvCoordinates = new FieldPVCoordinates<>(position, velocity,
-                                                                       new FieldVector3D<>(r.multiply(r2).reciprocal().multiply(-mu),
-                                                                                           position));
+        FieldVector3D<T> acceleration = new FieldVector3D<>(r.multiply(r2).reciprocal().multiply(-mu).add(0.1), position);
+        FieldPVCoordinates<T> pvCoordinates = new FieldPVCoordinates<>(position, velocity,acceleration);
         FieldCartesianOrbit<T>  fieldOrbit = new FieldCartesianOrbit<>(pvCoordinates, FramesFactory.getEME2000(), date, zero.add(mu));
         CartesianOrbit orbit = fieldOrbit.toOrbit();
         Assert.assertTrue(orbit.hasDerivatives());

src/test/java/org/orekit/orbits/KeplerianOrbitTest.java

@@ -27,6 +27,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Function;
 
+import org.hamcrest.CoreMatchers;
 import org.hamcrest.MatcherAssert;
 import org.hipparchus.analysis.UnivariateFunction;
 import org.hipparchus.analysis.differentiation.DSFactory;
@@ -1661,6 +1662,29 @@ public class KeplerianOrbitTest {
         Assert.assertEquals(0.0, normalized2.getTrueAnomalyDot()                   - withDerivatives.getTrueAnomalyDot(),                   1.0e-10);
 
     }
+    
+    @Test
+    public void testKeplerianToPvToKeplerian() {
+        // setup
+        Frame eci = FramesFactory.getGCRF();
+        AbsoluteDate date = AbsoluteDate.ARBITRARY_EPOCH;
+        double mu = Constants.EGM96_EARTH_MU;
+        KeplerianOrbit orbit = new KeplerianOrbit(6878e3, 0, 0, 0, 0, 0,
+                PositionAngle.TRUE, eci, date, mu);
+
+        // action
+        KeplerianOrbit pvOrbit = new KeplerianOrbit(orbit.getPVCoordinates(), eci, mu);
+
+        // verify
+        Assert.assertEquals(orbit.shiftedBy(1).getA(), pvOrbit.shiftedBy(1).getA(), 1e-6);
+        Assert.assertEquals(orbit.shiftedBy(1).getE(), pvOrbit.shiftedBy(1).getE(), 1e-14);
+        Assert.assertEquals(orbit.shiftedBy(1).getI(), pvOrbit.shiftedBy(1).getI(), 1e-10);
+        Assert.assertEquals(orbit.shiftedBy(1).getPerigeeArgument(), pvOrbit.shiftedBy(1).getPerigeeArgument(), 1e-10);
+        Assert.assertEquals(orbit.shiftedBy(1).getRightAscensionOfAscendingNode(), pvOrbit.shiftedBy(1).getRightAscensionOfAscendingNode(), 1e-10);
+        Assert.assertEquals(orbit.shiftedBy(1).getTrueAnomaly(), pvOrbit.shiftedBy(1).getTrueAnomaly(), 1e-10);
+
+    }
+
 
     @Before
     public void setUp() {