Allow SteadyLogSpiralPotential to work with zero pattern speed (#588

)
jobovy · Jun 28, 2023 · d3607dd · d3607dd
1 parent 51e8732
commit d3607dd
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Showing 2 changed files with 22 additions and 2 deletions.
diff --git a/galpy/potential/SteadyLogSpiralPotential.py b/galpy/potential/SteadyLogSpiralPotential.py
@@ -17,7 +17,7 @@ class SteadyLogSpiralPotential(planarPotential):
         \\Phi(R,\\phi) = \\frac{\\mathrm{amp}\\times A}{\\alpha}\\,\\cos\\left(\\alpha\\,\\ln R - m\\,(\\phi-\\Omega_s\\,t-\\gamma)\\right)
 
 
-    Can be grown in a similar way as the DehnenBarPotential, but using :math:`T_s = 2\\pi/\\Omega_s` to normalize :math:`t_{\\mathrm{form}}` and :math:`T_{\\mathrm{steady}}`.
+    Can be grown in a similar way as the DehnenBarPotential, but using :math:`T_s = 2\\pi/\\Omega_s` to normalize :math:`t_{\\mathrm{form}}` and :math:`t_{\\mathrm{steady}}`. If the pattern speed is zero, :math:`t_\\mathrm{form}` and :math:`t_\\mathrm{steady}` are straight times, not times divided by the spiral period.
 
     """
 
@@ -89,7 +89,7 @@ def __init__(
             self._alpha = self._m / numpy.tan(p)
         else:
             self._alpha = alpha
-        self._ts = 2.0 * numpy.pi / self._omegas
+        self._ts = 2.0 * numpy.pi / self._omegas if self._omegas != 0.0 else 1.0
         if not tform is None:
             self._tform = tform * self._ts
         else:

diff --git a/tests/test_potential.py b/tests/test_potential.py
@@ -162,6 +162,7 @@ def test_forceAsDeriv_potential():
     pots.append("mockEllipticalDiskPotentialTm5")
     pots.append("mockSteadyLogSpiralPotentialT1")
     pots.append("mockSteadyLogSpiralPotentialTm1")
+    pots.append("mockSteadyLogSpiralPotentialTm1Omega0")
     pots.append("mockSteadyLogSpiralPotentialTm5")
     pots.append("mockTransientLogSpiralPotential")
     pots.append("mockFlatEllipticalDiskPotential")  # for evaluate w/ nonaxi lists
@@ -410,6 +411,7 @@ def test_2ndDeriv_potential():
     pots.append("mockEllipticalDiskPotentialTm5")
     pots.append("mockSteadyLogSpiralPotentialT1")
     pots.append("mockSteadyLogSpiralPotentialTm1")
+    pots.append("mockSteadyLogSpiralPotentialTm1Omega0")
     pots.append("mockSteadyLogSpiralPotentialTm5")
     pots.append("mockTransientLogSpiralPotential")
     pots.append("mockFlatEllipticalDiskPotential")  # for evaluate w/ nonaxi lists
@@ -1083,6 +1085,7 @@ def test_evaluateAndDerivs_potential():
     pots.append("mockDehnenBarPotentialTm5")
     pots.append("mockEllipticalDiskPotentialT1")
     pots.append("mockEllipticalDiskPotentialTm1")
+    pots.append("mockSteadyLogSpiralPotentialTm1Omega0")
     pots.append("mockEllipticalDiskPotentialTm5")
     pots.append("mockSteadyLogSpiralPotentialT1")
     pots.append("mockSteadyLogSpiralPotentialTm1")
@@ -1350,6 +1353,7 @@ def test_amp_mult_divide():
     pots.append("mockDehnenBarPotentialTm5")
     pots.append("mockEllipticalDiskPotentialT1")
     pots.append("mockEllipticalDiskPotentialTm1")
+    pots.append("mockSteadyLogSpiralPotentialTm1Omega0")
     pots.append("mockEllipticalDiskPotentialTm5")
     pots.append("mockSteadyLogSpiralPotentialT1")
     pots.append("mockSteadyLogSpiralPotentialTm1")
@@ -8507,6 +8511,22 @@ def __init__(self):
         )
 
 
+# Also one with omegab=0. to test that that works
+class mockSteadyLogSpiralPotentialTm1Omega0(SteadyLogSpiralPotential):
+    def __init__(self):
+        SteadyLogSpiralPotential.__init__(
+            self,
+            amp=1.0,
+            omegas=0.0,
+            A=-0.035,
+            m=2,
+            gamma=numpy.pi / 4.0,
+            p=-0.3,
+            tform=-1.0,
+            tsteady=None,
+        )
+
+
 class mockSteadyLogSpiralPotentialTm5(SteadyLogSpiralPotential):
     def __init__(self):
         SteadyLogSpiralPotential.__init__(