Adds the 3MN potential of Smith et al. (2015)

HISTORY.txt

@@ -15,6 +15,10 @@ Current development version, last updated 12/26/2014:
   subclass of interpRZPotential and can be used in the same way). This
   code was mainly written by Rok Roskar.
 
+- Added MN3ExponentialDiskPotential that gives the approximation to a
+  radially-exponential disk potential as three Miyamoto-Nagai disks
+  from Smith et al. (2015; arXiv:1502.00627v1)
+
 - Add support for converting potential parameters to NEMO format and
   units: nemo_accname and nemo_accpars (both instance and general
   Potential method).

doc/source/potential.rst

@@ -501,10 +501,10 @@ LogarithmicHaloPotential, the radial force scales as :math:`R^{-1}`,
 so the amplitude scales as :math:`V_0^2`.
 
 Currently, only the ``MiyamotoNagaiPotential``, ``NFWPotential``,
-``PowerSphericalPotentialwCutoff``, and the
-``LogarithmicHaloPotential`` have this NEMO support. Combinations of
-the first three are also supported (e.g., ``MWPotential2014``); they
-can also be combined with spherical
+``PowerSphericalPotentialwCutoff``, ``MN3ExponentialDiskPotential``,
+and the ``LogarithmicHaloPotential`` have this NEMO
+support. Combinations of the first three are also supported (e.g.,
+``MWPotential2014``); they can also be combined with spherical
 ``LogarithmicHaloPotentials``. Because of the definition of the
 logarithmic potential in NEMO, it cannot be flattened in ``z``, so to
 use a flattened logarithmic potential, one has to flip ``y`` and ``z``

doc/source/reference/potential.rst

@@ -102,6 +102,7 @@ Specific potentials
    potentialkepler.rst
    potentialloghalo.rst
    potentialmiyamoto.rst
+   potential3mn.rst
    potentialmovingobj.rst
    potentialnfw.rst
    potentialpowerspher.rst

doc/source/reference/potential3mn.rst

@@ -0,0 +1,5 @@
+Three Miyamoto-Nagai disk approximation to an exponential disk
+================================================================
+
+.. autoclass:: galpy.potential.MN3ExponentialDiskPotential
+   :members: __init__

galpy/orbit_src/integrateFullOrbit.py

@@ -99,6 +99,16 @@ def _parse_pot(pot,potforactions=False):
         elif isinstance(p,potential.PowerSphericalPotentialwCutoff):
             pot_type.append(15)
             pot_args.extend([p._amp,p.alpha,p.rc])
+        elif isinstance(p,potential.MN3ExponentialDiskPotential):
+            # Three Miyamoto-Nagai disks
+            npot+= 2
+            pot_type.extend([5,5,5])
+            pot_args.extend([p._amp*p._mn3[0]._amp,
+                             p._mn3[0]._a,p._mn3[0]._b,
+                             p._amp*p._mn3[1]._amp,
+                             p._mn3[1]._a,p._mn3[1]._b,
+                             p._amp*p._mn3[2]._amp,
+                             p._mn3[2]._a,p._mn3[2]._b])
     pot_type= nu.array(pot_type,dtype=nu.int32,order='C')
     pot_args= nu.array(pot_args,dtype=nu.float64,order='C')
     return (npot,pot_type,pot_args)

galpy/orbit_src/integratePlanarOrbit.py

@@ -128,6 +128,17 @@ def _parse_pot(pot):
                  and isinstance(p._RZPot,potential.PowerSphericalPotentialwCutoff):
             pot_type.append(15)
             pot_args.extend([p._RZPot._amp,p._RZPot.alpha,p._RZPot.rc])
+        elif isinstance(p,potential_src.planarPotential.planarPotentialFromRZPotential) \
+                 and isinstance(p._RZPot,potential.MN3ExponentialDiskPotential):
+            # Three Miyamoto-Nagai disks
+            npot+= 2
+            pot_type.extend([5,5,5])
+            pot_args.extend([p._RZPot._amp*p._RZPot._mn3[0]._amp,
+                             p._RZPot._mn3[0]._a,p._RZPot._mn3[0]._b,
+                             p._RZPot._amp*p._RZPot._mn3[1]._amp,
+                             p._RZPot._mn3[1]._a,p._RZPot._mn3[1]._b,
+                             p._RZPot._amp*p._RZPot._mn3[2]._amp,
+                             p._RZPot._mn3[2]._a,p._RZPot._mn3[2]._b])
     pot_type= nu.array(pot_type,dtype=nu.int32,order='C')
     pot_args= nu.array(pot_args,dtype=nu.float64,order='C')
     return (npot,pot_type,pot_args)

galpy/potential.py

@@ -24,6 +24,7 @@
 from galpy.potential_src import FlattenedPowerPotential
 from galpy.potential_src import SnapshotRZPotential
 from galpy.potential_src import BurkertPotential
+from galpy.potential_src import MN3ExponentialDiskPotential
 #
 # Functions
 #
@@ -97,6 +98,7 @@
 InterpSnapshotRZPotential = SnapshotRZPotential.InterpSnapshotRZPotential
 SnapshotRZPotential = SnapshotRZPotential.SnapshotRZPotential
 BurkertPotential= BurkertPotential.BurkertPotential
+MN3ExponentialDiskPotential= MN3ExponentialDiskPotential.MN3ExponentialDiskPotential
 #Softenings
 PlummerSoftening= ForceSoftening.PlummerSoftening