Source code for galpy.actionAngle.actionAngleHarmonic

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#   actionAngle: a Python module to calculate  actions, angles, and frequencies
#
#      class: actionAngleHarmonic
#
#             Calculate actions-angle coordinates for the harmonic-oscillator
#
#      methods:
#             __call__: returns (j)
#             actionsFreqs: returns (j,omega)
#             actionsFreqsAngles: returns (j,omega,a)
#
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import numpy
from .actionAngle import actionAngle
from ..util import conversion
[docs]class actionAngleHarmonic(actionAngle): """Action-angle formalism for the one-dimensional harmonic oscillator"""
[docs] def __init__(self,*args,**kwargs): """ NAME: __init__ PURPOSE: initialize an actionAngleHarmonic object INPUT: omega= frequencies (can be Quantity) ro= distance from vantage point to GC (kpc; can be Quantity) vo= circular velocity at ro (km/s; can be Quantity) OUTPUT: instance HISTORY: 2018-04-08 - Written - Bovy (Uoft) """ actionAngle.__init__(self, ro=kwargs.get('ro',None),vo=kwargs.get('vo',None)) if not 'omega' in kwargs: #pragma: no cover raise IOError("Must specify omega= for actionAngleHarmonic") self._omega= conversion.parse_frequency(kwargs.get('omega'), ro=self._ro,vo=self._vo) return None
def _evaluate(self,*args,**kwargs): """ NAME: __call__ (_evaluate) PURPOSE: evaluate the action INPUT: Either: a) x,vx: 1) floats: phase-space value for single object (each can be a Quantity) 2) numpy.ndarray: [N] phase-space values for N objects (each can be a Quantity) OUTPUT: action HISTORY: 2018-04-08 - Written - Bovy (UofT) """ if len(args) == 2: # x,vx x,vx= args return (vx**2./self._omega+self._omega*x**2.)/2. else: # pragma: no cover raise ValueError('actionAngleHarmonic __call__ input not understood') def _actionsFreqs(self,*args,**kwargs): """ NAME: actionsFreqs (_actionsFreqs) PURPOSE: evaluate the action and frequency INPUT: Either: a) x,vx: 1) floats: phase-space value for single object (each can be a Quantity) 2) numpy.ndarray: [N] phase-space values for N objects (each can be a Quantity) OUTPUT: action,frequency HISTORY: 2018-04-08 - Written - Bovy (UofT) """ if len(args) == 2: # x,vx x,vx= args return ((vx**2./self._omega+self._omega*x**2.)/2., self._omega*numpy.ones_like(x)) else: # pragma: no cover raise ValueError('actionAngleHarmonic __call__ input not understood') def _actionsFreqsAngles(self,*args,**kwargs): """ NAME: actionsFreqsAngles (_actionsFreqsAngles) PURPOSE: evaluate the action, frequency, and angle INPUT: Either: a) x,vx: 1) floats: phase-space value for single object (each can be a Quantity) 2) numpy.ndarray: [N] phase-space values for N objects (each can be a Quantity) OUTPUT: action,frequency,angle HISTORY: 2018-04-08 - Written - Bovy (UofT) """ if len(args) == 2: # x,vx x,vx= args return ((vx**2./self._omega+self._omega*x**2.)/2., self._omega*numpy.ones_like(x), numpy.arctan2(self._omega*x,vx)) else: # pragma: no cover raise ValueError('actionAngleHarmonic __call__ input not understood')