def dvcircdR(Pot,R):
"""
NAME:
dvcircdR
PURPOSE:
calculate the derivative of the circular velocity wrt R at R in potential Pot
INPUT:
Pot - Potential instance or list of such instances
R - Galactocentric radius
OUTPUT:
derivative of the circular rotation velocity wrt R
HISTORY:
2013-01-08 - Written - Bovy (IAS)
"""
from planarPotential import evaluateplanarRforces
from planarPotential import evaluateplanarR2derivs
tvc= vcirc(Pot,R)
try:
return 0.5*(-evaluateplanarRforces(R,Pot)+R*evaluateplanarR2derivs(R,Pot))/tvc
except TypeError:
from planarPotential import RZToplanarPotential
Pot= RZToplanarPotential(Pot)
return 0.5*(-evaluateplanarRforces(R,Pot)+R*evaluateplanarR2derivs(R,Pot))/tvc
def epifreq(Pot,R):
"""
NAME:
epifreq
PURPOSE:
calculate the epicycle frequency at R in potential Pot
INPUT:
Pot - Potential instance or list of such instances
R - Galactocentric radius
OUTPUT:
epicycle frequency
HISTORY:
2011-10-09 - Written - Bovy (IAS)
"""
from planarPotential import evaluateplanarRforces, evaluateplanarR2derivs
try:
return nu.sqrt(evaluateplanarR2derivs(R,Pot)-3./R*evaluateplanarRforces(R,Pot))
except TypeError:
from planarPotential import RZToplanarPotential
Pot= RZToplanarPotential(Pot)
return nu.sqrt(evaluateplanarR2derivs(R,Pot)-3./R*evaluateplanarRforces(R,Pot))
def epifreq(Pot,R):
"""
NAME:
epifreq
PURPOSE:
calculate the epicycle frequency at R in the potential Pot
INPUT:
Pot - Potential instance or list thereof
R - Galactocentric radius
OUTPUT:
epicycle frequency
HISTORY:
2012-07-25 - Written - Bovy (IAS)
"""
from galpy.potential_src.planarPotential import planarPotential
if isinstance(Pot,(Potential,planarPotential)):
return Pot.epifreq(R)
from planarPotential import evaluateplanarRforces, evaluateplanarR2derivs
from Potential import PotentialError
try:
return nu.sqrt(evaluateplanarR2derivs(R,Pot)-3./R*evaluateplanarRforces(R,Pot))
except PotentialError:
from planarPotential import RZToplanarPotential
Pot= RZToplanarPotential(Pot)
return nu.sqrt(evaluateplanarR2derivs(R,Pot)-3./R*evaluateplanarRforces(R,Pot))
def epifreq(Pot, R):
"""
NAME:
epifreq
PURPOSE:
calculate the epicycle frequency at R in potential Pot
INPUT:
Pot - Potential instance or list of such instances
R - Galactocentric radius
OUTPUT:
epicycle frequency
HISTORY:
2011-10-09 - Written - Bovy (IAS)
"""
from planarPotential import evaluateplanarRforces, evaluateplanarR2derivs
try:
return nu.sqrt(
evaluateplanarR2derivs(R, Pot) -
3. / R * evaluateplanarRforces(R, Pot))
except TypeError:
from planarPotential import RZToplanarPotential
Pot = RZToplanarPotential(Pot)
return nu.sqrt(
evaluateplanarR2derivs(R, Pot) -
3. / R * evaluateplanarRforces(R, Pot))
