Up coverage

sbpy/activity/dust/dynamics.py

@@ -63,7 +63,8 @@ class State:
     t : `~astropy.time.Time`
         Time, a scalar or shape = (N,).
 
-    frame : `~astropy.coordinates.BaseCoordinateFrame` class or string, optional
+    frame : `~astropy.coordinates.BaseCoordinateFrame` class or string,
+            optional
         Coordinate frame for ``r`` and ``v``. Defaults to
         `~astropy.coordinates.HeliocentricEclipticIAU76` if given as ``None``.
 
@@ -104,7 +105,12 @@ def __init__(
             raise ValueError("Mismatch between lengths of vectors.")
 
     def __repr__(self) -> str:
-        return f"<{type(self).__name__} ({self.frame}):\n r\n    {self.r}\n v\n    {self.v}\n t\n    {self.t}>"
+        return (
+            f"<{type(self).__name__} ({self.frame}):\n"
+            + f" r\n    {self.r}\n"
+            + f" v\n    {self.v}\n"
+            + f" t\n    {self.t}>"
+        )
 
     def __len__(self):
         """Number of state vectors in this object."""
@@ -271,7 +277,11 @@ def transform_to(self, frame: FrameType) -> StateType:
 
         return State.from_skycoord(self.to_skycoord().transform_to(frame))
 
-    def observe(self, target: StateType, frame: Optional[FrameType] = None) -> SkyCoord:
+    def observe(
+        self,
+        target: StateType,
+        frame: Optional[FrameType] = None,
+    ) -> SkyCoord:
         """Project a target's position on to the sky.
 
 
@@ -319,7 +329,11 @@ def from_states(cls, states: Iterable[StateType]) -> StateType:
 
         r: np.ndarray = np.array([state.r for state in states])
         v: np.ndarray = np.array([state.v for state in states])
-        t: Time = Time([state.t.tdb.et for state in states], scale="tdb", format="et")
+        t: Time = Time(
+            [state.t.tdb.et for state in states],
+            scale="tdb",
+            format="et",
+        )
 
         return State(r, v, t, frame=list(frames)[0])
 
@@ -331,8 +345,8 @@ def from_skycoord(cls, coords: SkyCoord) -> StateType:
         Parameters
         ----------
         coords: ~astropy.coordinates.SkyCoord
-            The object state.  Must have position and velocity, ``obstime``, and
-            be convertible to cartesian (3D) coordinates.
+            The object state.  Must have position and velocity, ``obstime``,
+            and be convertible to cartesian (3D) coordinates.
 
         """
 
@@ -346,7 +360,11 @@ def from_skycoord(cls, coords: SkyCoord) -> StateType:
 
     @classmethod
     @sbd.dataclass_input
-    def from_ephem(cls, eph: Ephem, frame: Optional[FrameType] = None) -> StateType:
+    def from_ephem(
+        cls,
+        eph: Ephem,
+        frame: Optional[FrameType] = None,
+    ) -> StateType:
         """Initialize from an `~sbpy.data.Ephem` object.
 
 
@@ -355,8 +373,8 @@ def from_ephem(cls, eph: Ephem, frame: Optional[FrameType] = None) -> StateType:
         eph : ~sbpy.data.ephem.Ephem
             Ephemeris object, must have time, position, and velocity.  Position
             and velocity may be specified using ("x", "y", "z", "vx", "vy", and
-            "vz"), or ("ra", "dec", "Delta", "RA*cos(Dec)_rate", "Dec_rate", and
-            "deltadot").
+            "vz"), or ("ra", "dec", "Delta", "RA*cos(Dec)_rate", "Dec_rate",
+            and "deltadot").
 
         frame : string or `~astropy.coordinates.BaseCoordinateFrame`, optional
             Transform the coordinates into this reference frame.
@@ -486,8 +504,7 @@ def df_drv(cls, t: float, rv: np.ndarray, *args) -> np.ndarray:
             :math:`df/dv`.
 
         """
-
-
+
     def solve(
         self,
         initial: State,
@@ -599,8 +616,7 @@ def df_drv(cls, t: float, rv: np.ndarray, *args) -> np.ndarray:
         r = rv[:3]
         r2 = (r**2).sum()
         r1 = np.sqrt(r2)
-        GM_r3 = cls._GM
-        GM_r5 = GM_r3 / r2
+        GM_r5 = GM_r3 = cls._GM / (r2 * r2 * r1)
 
         # df_drv[i, j] = df_i/drv_j
         df_drv = np.zeros((6, 6))
@@ -682,8 +698,7 @@ def df_drv(cls, t: float, rv: np.ndarray, beta: float, *args) -> np.ndarray:
         r2 = (r**2).sum()
         r1 = np.sqrt(r2)
         r3 = r1 * r2
-        GM_r3 = cls._GM / r3 * (1 - beta)
-        GM_r5 = GM_r3 / r2
+        GM_r5 = cls._GM * (1 - beta) / (r2 * r3)
 
         # df_drv[i, j] = df_i/drv_j
         df_drv = np.zeros((6, 6))

sbpy/activity/dust/tests/test_dynamics.py

@@ -9,6 +9,7 @@
     SkyCoord,
     HeliocentricEclipticIAU76,
 )
+import astropy.constants as const
 
 from .... import time  # for ephemeris time
 from ....data import Ephem
@@ -539,6 +540,7 @@ def test_from_ephem(self):
             with pytest.raises(ValueError):
                 State.from_ephem(incomplete)
 
+
 def test_spice_prop2b():
     """Test case from SPICE NAIF toolkit prop2b, v2.2.0
 
@@ -582,6 +584,29 @@ class EarthGravity(SolarGravity):
     assert np.allclose(final.v.value, [0, 0.04464, -0.04464], atol=0.00001)
 
 
+class TestFreeExpansion:
+    def test(self):
+        r = [0, 1e6, 0]
+        v = [0, -1, 1]
+
+        solver = FreeExpansion()
+
+        initial = State(r, v, Time("2023-01-01"))
+        t_f = initial.t + 1e6 * u.s
+        final = solver.solve(initial, t_f)
+
+        assert np.allclose(final.r.value, [0, 0, 1e6], atol=2e-7)
+        assert np.allclose(final.v.value, [0, -1, 1])
+
+        solver = FreeExpansion(method="Radau")
+
+        initial = State(r, v, Time("2023-01-01"))
+        final = solver.solve(initial, t_f)
+
+        assert np.allclose(final.r.value, [0, 0, 1e6], atol=2e-7)
+        assert np.allclose(final.v.value, [0, -1, 1])
+
+
 class TestSolarGravity:
     @pytest.mark.parametrize("r1_au", ([0.3, 1, 3, 10, 30]))
     def test_circular_orbit(self, r1_au):
@@ -607,20 +632,28 @@ def test_circular_orbit(self, r1_au):
         assert np.allclose(final.r.value, initial.r.value)
         assert np.allclose(final.v.value, initial.v.value)
 
+        t_f = initial.t + half_period * u.s
+        solver = SolarGravity(method="Radau")
+        final = solver.solve(initial, t_f)
 
-class TestFreeExpansion:
-    def test(self):
-        r = [0, 1e6, 0]
-        v = [0, -1, 1]
+        assert np.allclose(final.r.value, -initial.r.value)
+        assert np.allclose(final.v.value, -initial.v.value)
 
-        solver = FreeExpansion()
+    def test_GM(self):
+        solver = SolarGravity()
+        assert u.isclose(solver.GM, const.G * const.M_sun)
+
+    def test_solverfailed(self):
+        r = [0, 1, 0] * u.au
+        v = [0, -1, 1] * u.km / u.s
+
+        # force a solution failure
+        solver = SolarGravity(rtol=np.nan)
 
         initial = State(r, v, Time("2023-01-01"))
         t_f = initial.t + 1e6 * u.s
-        final = solver.solve(initial, t_f)
-
-        assert np.allclose(final.r.value, [0, 0, 1e6], atol=2e-7)
-        assert np.allclose(final.v.value, [0, -1, 1])
+        with pytest.raises(SolverFailed):
+            solver.solve(initial, t_f)
 
 
 class TestSolarGravityAndRadiationPressure:
@@ -644,3 +677,9 @@ class ReducedGravity(SolarGravity):
 
         assert u.allclose(final1.r, final2.r)
         assert u.allclose(final1.v, final2.v)
+
+        solver = SolarGravityAndRadiationPressure(method="Radau")
+        final2 = solver.solve(initial, t_f, beta)
+
+        assert u.allclose(final1.r, final2.r)
+        assert u.allclose(final1.v, final2.v)