Source code for galpy.potential.Potential

###############################################################################
#   Potential.py: top-level class for a full potential
#
#   Evaluate by calling the instance: Pot(R,z,phi)
#
#   API for Potentials:
#      function _evaluate(self,R,z,phi) returns Phi(R,z,phi)
#    for orbit integration you need
#      function _Rforce(self,R,z,phi) return -d Phi d R
#      function _zforce(self,R,z,phi) return - d Phi d Z
#    density
#      function _dens(self,R,z,phi) return BOVY??
#    for epicycle frequency
#      function _R2deriv(self,R,z,phi) return d2 Phi dR2
###############################################################################
from __future__  import division, print_function

import os, os.path
import pickle
from functools import wraps
import warnings
import numpy
from scipy import optimize, integrate
from ..util import plot, coords, conversion
from ..util.conversion import velocity_in_kpcGyr, \
    physical_conversion, potential_physical_input, freq_in_Gyr, \
    get_physical
from ..util import galpyWarning
from .plotRotcurve import plotRotcurve, vcirc
from .plotEscapecurve import _INF, plotEscapecurve
from .DissipativeForce import DissipativeForce, _isDissipative
from .Force import Force, _APY_LOADED
if _APY_LOADED:
    from astropy import units
def check_potential_inputs_not_arrays(func):
    """
    NAME:
       check_potential_inputs_not_arrays
    PURPOSE:
       Decorator to check inputs and throw TypeError if any of the inputs are arrays for Potentials that do not support array evaluation
    HISTORY:
       2017-summer - Written for SpiralArmsPotential - Jack Hong (UBC)
       2019-05-23 - Moved to Potential for more general use - Bovy (UofT)
       
    """
    @wraps(func)
    def func_wrapper(self,R,z,phi,t):
        if (hasattr(R,'shape') and R.shape != () and len(R) > 1) \
                or (hasattr(z,'shape') and z.shape != () and len(z) > 1) \
                or (hasattr(phi,'shape') and phi.shape != () and len(phi) > 1) \
                or (hasattr(t,'shape') and t.shape != () and len(t) > 1):
            raise TypeError('Methods in {} do not accept array inputs. Please input scalars'.format(self.__class__.__name__))
        return func(self,R,z,phi,t)
    return func_wrapper


class Potential(Force):
    """Top-level class for a potential"""
    def __init__(self,amp=1.,ro=None,vo=None,amp_units=None):
        """
        NAME:
           __init__
        PURPOSE:
        INPUT:
           amp - amplitude to be applied when evaluating the potential and its forces
           amp_units - ('mass', 'velocity2', 'density') type of units that amp should have if it has units
        OUTPUT:
        HISTORY:
        """
        Force.__init__(self,amp=amp,ro=ro,vo=vo,amp_units=amp_units)
        self.dim= 3
        self.isRZ= True
        self.isNonAxi= False
        self.hasC= False
        self.hasC_dxdv= False
        self.hasC_dens= False
        return None

[docs] @potential_physical_input @physical_conversion('energy',pop=True) def __call__(self,R,z,phi=0.,t=0.,dR=0,dphi=0): """ NAME: __call__ PURPOSE: evaluate the potential at (R,z,phi,t) INPUT: R - Cylindrical Galactocentric radius (can be Quantity) z - vertical height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: Phi(R,z,t) HISTORY: 2010-04-16 - Written - Bovy (NYU) """ return self._call_nodecorator(R,z,phi=phi,t=t,dR=dR,dphi=dphi)
def _call_nodecorator(self,R,z,phi=0.,t=0.,dR=0.,dphi=0): if dR == 0 and dphi == 0: try: rawOut= self._evaluate(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover raise PotentialError("'_evaluate' function not implemented for this potential") if rawOut is None: return rawOut else: return self._amp*rawOut elif dR == 1 and dphi == 0: return -self.Rforce(R,z,phi=phi,t=t,use_physical=False) elif dR == 0 and dphi == 1: return -self.phiforce(R,z,phi=phi,t=t,use_physical=False) elif dR == 2 and dphi == 0: return self.R2deriv(R,z,phi=phi,t=t,use_physical=False) elif dR == 0 and dphi == 2: return self.phi2deriv(R,z,phi=phi,t=t,use_physical=False) elif dR == 1 and dphi == 1: return self.Rphideriv(R,z,phi=phi,t=t,use_physical=False) elif dR != 0 or dphi != 0: raise NotImplementedError('Higher-order derivatives not implemented for this potential')
[docs] @potential_physical_input @physical_conversion('force',pop=True) def Rforce(self,R,z,phi=0.,t=0.): """ NAME: Rforce PURPOSE: evaluate cylindrical radial force F_R (R,z) INPUT: R - Cylindrical Galactocentric radius (can be Quantity) z - vertical height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: F_R (R,z,phi,t) HISTORY: 2010-04-16 - Written - Bovy (NYU) """ return self._Rforce_nodecorator(R,z,phi=phi,t=t)
def _Rforce_nodecorator(self,R,z,phi=0.,t=0.): # Separate, so it can be used during orbit integration try: return self._amp*self._Rforce(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover raise PotentialError("'_Rforce' function not implemented for this potential")
[docs] @potential_physical_input @physical_conversion('force',pop=True) def zforce(self,R,z,phi=0.,t=0.): """ NAME: zforce PURPOSE: evaluate the vertical force F_z (R,z,t) INPUT: R - Cylindrical Galactocentric radius (can be Quantity) z - vertical height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: F_z (R,z,phi,t) HISTORY: 2010-04-16 - Written - Bovy (NYU) """ return self._zforce_nodecorator(R,z,phi=phi,t=t)
def _zforce_nodecorator(self,R,z,phi=0.,t=0.): # Separate, so it can be used during orbit integration try: return self._amp*self._zforce(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover raise PotentialError("'_zforce' function not implemented for this potential")
[docs] @potential_physical_input @physical_conversion('forcederivative',pop=True) def r2deriv(self,R,z,phi=0.,t=0.): """ NAME: r2deriv PURPOSE: evaluate the second spherical radial derivative INPUT: R - Cylindrical Galactocentric radius (can be Quantity) z - vertical height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: d2phi/dr2 HISTORY: 2018-03-21 - Written - Webb (UofT) """ r= numpy.sqrt(R**2.+z**2.) return (self.R2deriv(R,z,phi=phi,t=t,use_physical=False)*R/r\ +self.Rzderiv(R,z,phi=phi,t=t,use_physical=False)*z/r)*R/r\ +(self.Rzderiv(R,z,phi=phi,t=t,use_physical=False)*R/r\ +self.z2deriv(R,z,phi=phi,t=t,use_physical=False)*z/r)*z/r
[docs] @potential_physical_input @physical_conversion('density',pop=True) def dens(self,R,z,phi=0.,t=0.,forcepoisson=False): """ NAME: dens PURPOSE: evaluate the density rho(R,z,t) INPUT: R - Cylindrical Galactocentric radius (can be Quantity) z - vertical height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) KEYWORDS: forcepoisson= if True, calculate the density through the Poisson equation, even if an explicit expression for the density exists OUTPUT: rho (R,z,phi,t) HISTORY: 2010-08-08 - Written - Bovy (NYU) """ try: if forcepoisson: raise AttributeError #Hack! return self._amp*self._dens(R,z,phi=phi,t=t) except AttributeError: #Use the Poisson equation to get the density return (-self.Rforce(R,z,phi=phi,t=t,use_physical=False)/R +self.R2deriv(R,z,phi=phi,t=t,use_physical=False) +self.phi2deriv(R,z,phi=phi,t=t,use_physical=False)/R**2. +self.z2deriv(R,z,phi=phi,t=t,use_physical=False))/4./numpy.pi
[docs] @potential_physical_input @physical_conversion('surfacedensity',pop=True) def surfdens(self,R,z,phi=0.,t=0.,forcepoisson=False): """ NAME: surfdens PURPOSE: evaluate the surface density :math:`\\Sigma(R,z,\\phi,t) = \\int_{-z}^{+z} dz' \\rho(R,z',\\phi,t)` INPUT: R - Cylindrical Galactocentric radius (can be Quantity) z - vertical height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) KEYWORDS: forcepoisson= if True, calculate the surface density through the Poisson equation, even if an explicit expression for the surface density exists OUTPUT: Sigma (R,z,phi,t) HISTORY: 2018-08-19 - Written - Bovy (UofT) 2021-04-19 - Adjusted for non-z-symmetric densities - Bovy (UofT) """ try: if forcepoisson: raise AttributeError #Hack! return self._amp*self._surfdens(R,z,phi=phi,t=t) except AttributeError: #Use the Poisson equation to get the surface density return (-self.zforce(R,numpy.fabs(z),phi=phi,t=t,use_physical=False) +self.zforce(R,-numpy.fabs(z),phi=phi,t=t,use_physical=False) +integrate.quad(\ lambda x: -self.Rforce(R,x,phi=phi,t=t,use_physical=False)/R +self.R2deriv(R,x,phi=phi,t=t,use_physical=False) +self.phi2deriv(R,x,phi=phi,t=t,use_physical=False)/R**2., -numpy.fabs(z),numpy.fabs(z))[0])/4./numpy.pi
def _surfdens(self,R,z,phi=0.,t=0.): """ NAME: _surfdens PURPOSE: evaluate the surface density for this potential INPUT: R - Galactocentric cylindrical radius z - vertical height phi - azimuth t - time OUTPUT: the surface density HISTORY: 2018-08-19 - Written - Bovy (UofT) 2021-04-19 - Adjusted for non-z-symmetric densities - Bovy (UofT) """ return integrate.quad(lambda x: self._dens(R,x,phi=phi,t=t), -numpy.fabs(z),numpy.fabs(z))[0]
[docs] @potential_physical_input @physical_conversion('mass',pop=True) def mass(self,R,z=None,t=0.,forceint=False): """ NAME: mass PURPOSE: evaluate the mass enclosed INPUT: R - Cylindrical Galactocentric radius (can be Quantity) z= (None) vertical height up to which to integrate (can be Quantity) t - time (optional; can be Quantity) forceint= if True, calculate the mass through integration of the density, even if an explicit expression for the mass exists OUTPUT: Mass enclosed within the spherical shell with radius R if z is None else mass in the slab <R and between -z and z; except: potentials inheriting from EllipsoidalPotential, which if z is None return the mass within the ellipsoidal shell with semi-major axis R HISTORY: 2014-01-29 - Written - Bovy (IAS) 2019-08-15 - Added spherical warning - Bovy (UofT) 2021-03-15 - Changed to integrate to spherical shell for z is None slab otherwise - Bovy (UofT) 2021-03-18 - Switched to using Gauss' theorem - Bovy (UofT) """ from .EllipsoidalPotential import EllipsoidalPotential if self.isNonAxi and not isinstance(self,EllipsoidalPotential): raise NotImplementedError('mass for non-axisymmetric potentials that are not EllipsoidalPotentials is not currently supported') try: if forceint: raise AttributeError #Hack! return self._amp*self._mass(R,z=z,t=t) except AttributeError: #Use numerical integration to get the mass, using Gauss' theorem if z is None: # Within spherical shell def _integrand(theta): tz= R*numpy.cos(theta) tR= R*numpy.sin(theta) return self.rforce(tR,tz,t=t,use_physical=False)\ *numpy.sin(theta) return -R**2.*integrate.quad(_integrand,0.,numpy.pi)[0]/2. else: # Within disk at <R, -z --> z return -R*integrate.quad(lambda x: self.Rforce(R,x,t=t, use_physical=False), -z,z)[0]/2.\ -integrate.quad(lambda x: x*self.zforce(x,z,t=t, use_physical=False), 0.,R)[0]
[docs] @physical_conversion('position',pop=True) def rhalf(self,t=0.,INF=numpy.inf): """ NAME: rhalf PURPOSE: calculate the half-mass radius, the radius of the spherical shell that contains half the total mass INPUT: t= (0.) time (optional; can be Quantity) INF= (numpy.inf) radius at which the total mass is calculated (internal units, just set this to something very large) OUTPUT: half-mass radius HISTORY: 2021-03-18 - Written - Bovy (UofT) """ return rhalf(self,t=t,INF=INF,use_physical=False)
[docs] @potential_physical_input @physical_conversion('time',pop=True) def tdyn(self,R,t=0.): """ NAME: tdyn PURPOSE: calculate the dynamical time from tdyn^2 = 3pi/[G<rho>] INPUT: R - Galactocentric radius (can be Quantity) t= (0.) time (optional; can be Quantity) OUTPUT: Dynamical time HISTORY: 2021-03-18 - Written - Bovy (UofT) """ return 2.*numpy.pi*R*numpy.sqrt(R/self.mass(R,use_physical=False))
[docs] @physical_conversion('mass',pop=False) def mvir(self,H=70.,Om=0.3,t=0.,overdens=200.,wrtcrit=False, forceint=False,ro=None,vo=None, use_physical=False): # use_physical necessary bc of pop=False, does nothing inside """ NAME: mvir PURPOSE: calculate the virial mass INPUT: H= (default: 70) Hubble constant in km/s/Mpc Om= (default: 0.3) Omega matter overdens= (200) overdensity which defines the virial radius wrtcrit= (False) if True, the overdensity is wrt the critical density rather than the mean matter density ro= distance scale in kpc or as Quantity (default: object-wide, which if not set is 8 kpc)) vo= velocity scale in km/s or as Quantity (default: object-wide, which if not set is 220 km/s)) KEYWORDS: forceint= if True, calculate the mass through integration of the density, even if an explicit expression for the mass exists OUTPUT: M(<rvir) HISTORY: 2014-09-12 - Written - Bovy (IAS) """ if ro is None: ro= self._ro if vo is None: vo= self._vo #Evaluate the virial radius try: rvir= self.rvir(H=H,Om=Om,t=t,overdens=overdens,wrtcrit=wrtcrit, use_physical=False,ro=ro,vo=vo) except AttributeError: raise AttributeError("This potential does not have a '_scale' defined to base the concentration on or does not support calculating the virial radius") return self.mass(rvir,t=t,forceint=forceint,use_physical=False,ro=ro,vo=vo)
[docs] @potential_physical_input @physical_conversion('forcederivative',pop=True) def R2deriv(self,R,z,phi=0.,t=0.): """ NAME: R2deriv PURPOSE: evaluate the second radial derivative INPUT: R - Galactocentric radius (can be Quantity) z - vertical height (can be Quantity) phi - Galactocentric azimuth (can be Quantity) t - time (can be Quantity) OUTPUT: d2phi/dR2 HISTORY: 2011-10-09 - Written - Bovy (IAS) """ try: return self._amp*self._R2deriv(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover raise PotentialError("'_R2deriv' function not implemented for this potential")
[docs] @potential_physical_input @physical_conversion('forcederivative',pop=True) def z2deriv(self,R,z,phi=0.,t=0.): """ NAME: z2deriv PURPOSE: evaluate the second vertical derivative INPUT: R - Galactocentric radius (can be Quantity) z - vertical height (can be Quantity) phi - Galactocentric azimuth (can be Quantity) t - time (can be Quantity) OUTPUT: d2phi/dz2 HISTORY: 2012-07-25 - Written - Bovy (IAS@MPIA) """ try: return self._amp*self._z2deriv(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover raise PotentialError("'_z2deriv' function not implemented for this potential")
[docs] @potential_physical_input @physical_conversion('forcederivative',pop=True) def Rzderiv(self,R,z,phi=0.,t=0.): """ NAME: Rzderiv PURPOSE: evaluate the mixed R,z derivative INPUT: R - Galactocentric radius (can be Quantity) Z - vertical height (can be Quantity) phi - Galactocentric azimuth (can be Quantity) t - time (can be Quantity) OUTPUT: d2phi/dz/dR HISTORY: 2013-08-26 - Written - Bovy (IAS) """ try: return self._amp*self._Rzderiv(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover raise PotentialError("'_Rzderiv' function not implemented for this potential")
def normalize(self,norm): """ NAME: normalize PURPOSE: normalize a potential in such a way that vc(R=1,z=0)=1., or a fraction of this INPUT: norm - normalize such that Rforce(R=1,z=0) is such that it is 'norm' of the force necessary to make vc(R=1,z=0)=1 (if True, norm=1) OUTPUT: (none) HISTORY: 2010-07-10 - Written - Bovy (NYU) """ self._amp*= norm/numpy.fabs(self.Rforce(1.,0.,use_physical=False))
[docs] @potential_physical_input @physical_conversion('energy',pop=True) def phiforce(self,R,z,phi=0.,t=0.): """ NAME: phiforce PURPOSE: evaluate the azimuthal force F_phi = -d Phi / d phi (R,z,phi,t) [note that this is a torque, not a force!) INPUT: R - Cylindrical Galactocentric radius (can be Quantity) z - vertical height (can be Quantity) phi - azimuth (rad; can be Quantity) t - time (optional; can be Quantity) OUTPUT: F_phi (R,z,phi,t) HISTORY: 2010-07-10 - Written - Bovy (NYU) """ return self._phiforce_nodecorator(R,z,phi=phi,t=t)
def _phiforce_nodecorator(self,R,z,phi=0.,t=0.): # Separate, so it can be used during orbit integration try: return self._amp*self._phiforce(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover if self.isNonAxi: raise PotentialError("'_phiforce' function not implemented for this non-axisymmetric potential") return 0.
[docs] @potential_physical_input @physical_conversion('energy',pop=True) def phi2deriv(self,R,z,phi=0.,t=0.): """ NAME: phi2deriv PURPOSE: evaluate the second azimuthal derivative INPUT: R - Galactocentric radius (can be Quantity) Z - vertical height (can be Quantity) phi - Galactocentric azimuth (can be Quantity) t - time (can be Quantity) OUTPUT: d2Phi/dphi2 HISTORY: 2013-09-24 - Written - Bovy (IAS) """ try: return self._amp*self._phi2deriv(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover if self.isNonAxi: raise PotentialError("'_phi2deriv' function not implemented for this non-axisymmetric potential") return 0.
[docs] @potential_physical_input @physical_conversion('force',pop=True) def Rphideriv(self,R,z,phi=0.,t=0.): """ NAME: Rphideriv PURPOSE: evaluate the mixed radial, azimuthal derivative INPUT: R - Galactocentric radius (can be Quantity) Z - vertical height (can be Quantity) phi - Galactocentric azimuth (can be Quantity) t - time (can be Quantity) OUTPUT: d2Phi/dphidR HISTORY: 2014-06-30 - Written - Bovy (IAS) """ try: return self._amp*self._Rphideriv(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover if self.isNonAxi: raise PotentialError("'_Rphideriv' function not implemented for this non-axisymmetric potential") return 0.
[docs] @potential_physical_input @physical_conversion('force',pop=True) def phizderiv(self,R,z,phi=0.,t=0.): """ NAME: phizderiv PURPOSE: evaluate the mixed azimuthal,vertical derivative INPUT: R - Galactocentric radius (can be Quantity) Z - vertical height (can be Quantity) phi - Galactocentric azimuth (can be Quantity) t - time (can be Quantity) OUTPUT: d2Phi/dphidz HISTORY: 2021-04-30 - Written - Bovy (UofT) """ try: return self._amp*self._phizderiv(R,z,phi=phi,t=t) except AttributeError: #pragma: no cover if self.isNonAxi: raise PotentialError("'_phizderiv' function not implemented for this non-axisymmetric potential") return 0.
[docs] def toPlanar(self): """ NAME: toPlanar PURPOSE: convert a 3D potential into a planar potential in the mid-plane INPUT: (none) OUTPUT: planarPotential HISTORY: unknown """ from ..potential import toPlanarPotential return toPlanarPotential(self)
[docs] def toVertical(self,R,phi=None,t0=0.): """ NAME: toVertical PURPOSE: convert a 3D potential into a linear (vertical) potential at R INPUT: R - Galactocentric radius at which to create the vertical potential (can be Quantity) phi= (None) Galactocentric azimuth at which to create the vertical potential (can be Quantity); required for non-axisymmetric potential t0= (0.) time at which to create the vertical potential (can be Quantity) OUTPUT: linear (vertical) potential: Phi(z,phi,t) = Phi(R,z,phi,t)-Phi(R,0.,phi0,t0) where phi0 and t0 are the phi and t inputs HISTORY unknown """ from ..potential import toVerticalPotential return toVerticalPotential(self,R,phi=phi,t0=t0)
[docs] def plot(self,t=0.,rmin=0.,rmax=1.5,nrs=21,zmin=-0.5,zmax=0.5,nzs=21, effective=False,Lz=None,phi=None,xy=False, xrange=None,yrange=None, justcontours=False,levels=None,cntrcolors=None, ncontours=21,savefilename=None): """ NAME: plot PURPOSE: plot the potential INPUT: t= time to plot potential at rmin= minimum R (can be Quantity) [xmin if xy] rmax= maximum R (can be Quantity) [ymax if xy] nrs= grid in R zmin= minimum z (can be Quantity) [ymin if xy] zmax= maximum z (can be Quantity) [ymax if xy] nzs= grid in z phi= (None) azimuth to use for non-axisymmetric potentials xy= (False) if True, plot the potential in X-Y effective= (False) if True, plot the effective potential Phi + Lz^2/2/R^2 Lz= (None) angular momentum to use for the effective potential when effective=True justcontours= (False) if True, just plot contours savefilename - save to or restore from this savefile (pickle) xrange, yrange= can be specified independently from rmin,zmin, etc. levels= (None) contours to plot ncontours - number of contours when levels is None cntrcolors= (None) colors of the contours (single color or array with length ncontours) OUTPUT: plot to output device HISTORY: 2010-07-09 - Written - Bovy (NYU) 2014-04-08 - Added effective= - Bovy (IAS) """ rmin= conversion.parse_length(rmin,ro=self._ro) rmax= conversion.parse_length(rmax,ro=self._ro) zmin= conversion.parse_length(zmin,ro=self._ro) zmax= conversion.parse_length(zmax,ro=self._ro) if xrange is None: xrange= [rmin,rmax] if yrange is None: yrange= [zmin,zmax] if not savefilename is None and os.path.exists(savefilename): print("Restoring savefile "+savefilename+" ...") savefile= open(savefilename,'rb') potRz= pickle.load(savefile) Rs= pickle.load(savefile) zs= pickle.load(savefile) savefile.close() else: if effective and Lz is None: raise RuntimeError("When effective=True, you need to specify Lz=") Rs= numpy.linspace(xrange[0],xrange[1],nrs) zs= numpy.linspace(yrange[0],yrange[1],nzs) potRz= numpy.zeros((nrs,nzs)) for ii in range(nrs): for jj in range(nzs): if xy: R,phi,z= coords.rect_to_cyl(Rs[ii],zs[jj],0.) else: R,z= Rs[ii], zs[jj] potRz[ii,jj]= evaluatePotentials(self, R,z,t=t,phi=phi, use_physical=False) if effective: potRz[ii,:]+= 0.5*Lz**2/Rs[ii]**2. #Don't plot outside of the desired range potRz[Rs < rmin,:]= numpy.nan potRz[Rs > rmax,:]= numpy.nan potRz[:,zs < zmin]= numpy.nan potRz[:,zs > zmax]= numpy.nan if not savefilename == None: print("Writing savefile "+savefilename+" ...") savefile= open(savefilename,'wb') pickle.dump(potRz,savefile) pickle.dump(Rs,savefile) pickle.dump(zs,savefile) savefile.close() if xy: xlabel= r'$x/R_0$' ylabel= r'$y/R_0$' else: xlabel=r"$R/R_0$" ylabel=r"$z/R_0$" if levels is None: levels= numpy.linspace(numpy.nanmin(potRz),numpy.nanmax(potRz),ncontours) if cntrcolors is None: cntrcolors= 'k' return plot.dens2d(potRz.T,origin='lower',cmap='gist_gray',contours=True, xlabel=xlabel,ylabel=ylabel, xrange=xrange, yrange=yrange, aspect=.75*(rmax-rmin)/(zmax-zmin), cntrls='-', justcontours=justcontours, levels=levels,cntrcolors=cntrcolors)
[docs] def plotDensity(self,t=0., rmin=0.,rmax=1.5,nrs=21,zmin=-0.5,zmax=0.5,nzs=21, phi=None,xy=False, ncontours=21,savefilename=None,aspect=None,log=False, justcontours=False,**kwargs): """ NAME: plotDensity PURPOSE: plot the density of this potential INPUT: t= time to plot potential at rmin= minimum R (can be Quantity) [xmin if xy] rmax= maximum R (can be Quantity) [ymax if xy] nrs= grid in R zmin= minimum z (can be Quantity) [ymin if xy] zmax= maximum z (can be Quantity) [ymax if xy] nzs= grid in z phi= (None) azimuth to use for non-axisymmetric potentials xy= (False) if True, plot the density in X-Y ncontours= number of contours justcontours= (False) if True, just plot contours savefilename= save to or restore from this savefile (pickle) log= if True, plot the log density OUTPUT: plot to output device HISTORY: 2014-01-05 - Written - Bovy (IAS) """ return plotDensities(self,rmin=rmin,rmax=rmax,nrs=nrs, zmin=zmin,zmax=zmax,nzs=nzs,phi=phi,xy=xy,t=t, ncontours=ncontours,savefilename=savefilename, justcontours=justcontours, aspect=aspect,log=log,**kwargs)
[docs] def plotSurfaceDensity(self,t=0.,z=numpy.inf, xmin=0.,xmax=1.5,nxs=21,ymin=-0.5,ymax=0.5,nys=21, ncontours=21,savefilename=None,aspect=None, log=False,justcontours=False,**kwargs): """ NAME: plotSurfaceDensity PURPOSE: plot the surface density of this potential INPUT: t= time to plot potential at z= (inf) height between which to integrate the density (from -z to z; can be a Quantity) xmin= minimum x (can be Quantity) xmax= maximum x (can be Quantity) nxs= grid in x ymin= minimum y (can be Quantity) ymax= maximum y (can be Quantity) nys= grid in y ncontours= number of contours justcontours= (False) if True, just plot contours savefilename= save to or restore from this savefile (pickle) log= if True, plot the log density OUTPUT: plot to output device HISTORY: 2020-08-19 - Written - Bovy (UofT) """ return plotSurfaceDensities(self,xmin=xmin,xmax=xmax,nxs=nxs, ymin=ymin,ymax=ymax,nys=nys,t=t,z=z, ncontours=ncontours, savefilename=savefilename, justcontours=justcontours, aspect=aspect,log=log,**kwargs)
[docs] @potential_physical_input @physical_conversion('velocity',pop=True) def vcirc(self,R,phi=None,t=0.): """ NAME: vcirc PURPOSE: calculate the circular velocity at R in this potential INPUT: R - Galactocentric radius (can be Quantity) phi= (None) azimuth to use for non-axisymmetric potentials t - time (optional; can be Quantity) OUTPUT: circular rotation velocity HISTORY: 2011-10-09 - Written - Bovy (IAS) 2016-06-15 - Added phi= keyword for non-axisymmetric potential - Bovy (UofT) """ return numpy.sqrt(R*-self.Rforce(R,0.,phi=phi,t=t,use_physical=False))
[docs] @potential_physical_input @physical_conversion('frequency',pop=True) def dvcircdR(self,R,phi=None,t=0.): """ NAME: dvcircdR PURPOSE: calculate the derivative of the circular velocity at R wrt R in this potential INPUT: R - Galactocentric radius (can be Quantity) phi= (None) azimuth to use for non-axisymmetric potentials t - time (optional; can be Quantity) OUTPUT: derivative of the circular rotation velocity wrt R HISTORY: 2013-01-08 - Written - Bovy (IAS) 2016-06-28 - Added phi= keyword for non-axisymmetric potential - Bovy (UofT) """ return 0.5*(-self.Rforce(R,0.,phi=phi,t=t,use_physical=False)\ +R*self.R2deriv(R,0.,phi=phi,t=t,use_physical=False))\ /self.vcirc(R,phi=phi,t=t,use_physical=False)
[docs] @potential_physical_input @physical_conversion('frequency',pop=True) def omegac(self,R,t=0.): """ NAME: omegac PURPOSE: calculate the circular angular speed at R in this potential INPUT: R - Galactocentric radius (can be Quantity) t - time (optional; can be Quantity) OUTPUT: circular angular speed HISTORY: 2011-10-09 - Written - Bovy (IAS) """ return numpy.sqrt(-self.Rforce(R,0.,t=t,use_physical=False)/R)
[docs] @potential_physical_input @physical_conversion('frequency',pop=True) def epifreq(self,R,t=0.): """ NAME: epifreq PURPOSE: calculate the epicycle frequency at R in this potential INPUT: R - Galactocentric radius (can be Quantity) t - time (optional; can be Quantity) OUTPUT: epicycle frequency HISTORY: 2011-10-09 - Written - Bovy (IAS) """ return numpy.sqrt(self.R2deriv(R,0.,t=t,use_physical=False)\ -3./R*self.Rforce(R,0.,t=t,use_physical=False))
[docs] @potential_physical_input @physical_conversion('frequency',pop=True) def verticalfreq(self,R,t=0.): """ NAME: verticalfreq PURPOSE: calculate the vertical frequency at R in this potential INPUT: R - Galactocentric radius (can be Quantity) t - time (optional; can be Quantity) OUTPUT: vertical frequency HISTORY: 2012-07-25 - Written - Bovy (IAS@MPIA) """ return numpy.sqrt(self.z2deriv(R,0.,t=t,use_physical=False))
[docs] @physical_conversion('position',pop=True) def lindbladR(self,OmegaP,m=2,t=0.,**kwargs): """ NAME: lindbladR PURPOSE: calculate the radius of a Lindblad resonance INPUT: OmegaP - pattern speed (can be Quantity) m= order of the resonance (as in m(O-Op)=kappa (negative m for outer) use m='corotation' for corotation +scipy.optimize.brentq xtol,rtol,maxiter kwargs t - time (optional; can be Quantity) OUTPUT: radius of Linblad resonance, None if there is no resonance HISTORY: 2011-10-09 - Written - Bovy (IAS) """ OmegaP= conversion.parse_frequency(OmegaP,ro=self._ro,vo=self._vo) return lindbladR(self,OmegaP,m=m,t=t,use_physical=False,**kwargs)
[docs] @potential_physical_input @physical_conversion('velocity',pop=True) def vesc(self,R,t=0.): """ NAME: vesc PURPOSE: calculate the escape velocity at R for this potential INPUT: R - Galactocentric radius (can be Quantity) t - time (optional; can be Quantity) OUTPUT: escape velocity HISTORY: 2011-10-09 - Written - Bovy (IAS) """ return numpy.sqrt(2.*(self(_INF,0.,t=t,use_physical=False)\ -self(R,0.,t=t,use_physical=False)))
[docs] @physical_conversion('position',pop=True) def rl(self,lz,t=0.): """ NAME: rl PURPOSE: calculate the radius of a circular orbit of Lz INPUT: lz - Angular momentum (can be Quantity) t - time (optional; can be Quantity) OUTPUT: radius HISTORY: 2012-07-30 - Written - Bovy (IAS@MPIA) NOTE: An efficient way to call this function on many objects is provided as the Orbit method rguiding """ lz= conversion.parse_angmom(lz,ro=self._ro,vo=self._vo) return rl(self,lz,t=t,use_physical=False)
[docs] @physical_conversion('position',pop=True) def rE(self,E,t=0.): """ NAME: rE PURPOSE: calculate the radius of a circular orbit with energy E INPUT: E - Energy (can be Quantity) t - time (optional; can be Quantity) OUTPUT: radius HISTORY: 2022-04-06 - Written - Bovy (UofT) NOTE: An efficient way to call this function on many objects is provided as the Orbit method rE """ E= conversion.parse_energy(E,ro=self._ro,vo=self._vo) return rE(self,E,t=t,use_physical=False)
[docs] @physical_conversion('action',pop=True) def LcE(self,E,t=0.): """ NAME: LcE PURPOSE: calculate the angular momentum of a circular orbit with energy E INPUT: E - Energy (can be Quantity) t - time (optional; can be Quantity) OUTPUT: Lc(E) HISTORY: 2022-04-06 - Written - Bovy (UofT) """ E= conversion.parse_energy(E,ro=self._ro,vo=self._vo) return LcE(self,E,t=t,use_physical=False)
[docs] @potential_physical_input @physical_conversion('dimensionless',pop=True) def flattening(self,R,z,t=0.): """ NAME: flattening PURPOSE: calculate the potential flattening, defined as sqrt(fabs(z/R F_R/F_z)) INPUT: R - Galactocentric radius (can be Quantity) z - height (can be Quantity) t - time (optional; can be Quantity) OUTPUT: flattening HISTORY: 2012-09-13 - Written - Bovy (IAS) """ return numpy.sqrt(numpy.fabs(z/R*self.Rforce(R,z,t=t,use_physical=False)\ /self.zforce(R,z,t=t,use_physical=False)))
[docs] @physical_conversion('velocity',pop=True) def vterm(self,l,t=0.,deg=True): """ NAME: vterm PURPOSE: calculate the terminal velocity at l in this potential INPUT: l - Galactic longitude [deg/rad; can be Quantity) t - time (optional; can be Quantity) deg= if True (default), l in deg OUTPUT: terminal velocity HISTORY: 2013-05-31 - Written - Bovy (IAS) """ if _APY_LOADED and isinstance(l,units.Quantity): l= conversion.parse_angle(l) deg= False if deg: sinl= numpy.sin(l/180.*numpy.pi) else: sinl= numpy.sin(l) return sinl*(self.omegac(numpy.fabs(sinl),t=t,use_physical=False)\ -self.omegac(1.,t=t,use_physical=False))
[docs] def plotRotcurve(self,*args,**kwargs): """ NAME: plotRotcurve PURPOSE: plot the rotation curve for this potential (in the z=0 plane for non-spherical potentials) INPUT: Rrange - range (can be Quantity) grid= number of points to plot savefilename=- save to or restore from this savefile (pickle) +galpy.util.plot.plot(*args,**kwargs) OUTPUT: plot to output device HISTORY: 2010-07-10 - Written - Bovy (NYU) """ return plotRotcurve(self,*args,**kwargs)
[docs] def plotEscapecurve(self,*args,**kwargs): """ NAME: plotEscapecurve PURPOSE: plot the escape velocity curve for this potential (in the z=0 plane for non-spherical potentials) INPUT: Rrange - range (can be Quantity) grid= number of points to plot savefilename= save to or restore from this savefile (pickle) +galpy.util.plot.plot(*args,**kwargs) OUTPUT: plot to output device HISTORY: 2010-08-08 - Written - Bovy (NYU) """ return plotEscapecurve(self.toPlanar(),*args,**kwargs)
[docs] def conc(self,H=70.,Om=0.3,t=0.,overdens=200.,wrtcrit=False, ro=None,vo=None): """ NAME: conc PURPOSE: return the concentration INPUT: H= (default: 70) Hubble constant in km/s/Mpc Om= (default: 0.3) Omega matter t - time (optional; can be Quantity) overdens= (200) overdensity which defines the virial radius wrtcrit= (False) if True, the overdensity is wrt the critical density rather than the mean matter density ro= distance scale in kpc or as Quantity (default: object-wide, which if not set is 8 kpc)) vo= velocity scale in km/s or as Quantity (default: object-wide, which if not set is 220 km/s)) OUTPUT: concentration (scale/rvir) HISTORY: 2014-04-03 - Written - Bovy (IAS) """ if ro is None: ro= self._ro if vo is None: vo= self._vo try: return self.rvir(H=H,Om=Om,t=t,overdens=overdens,wrtcrit=wrtcrit, ro=ro,vo=vo,use_physical=False)/self._scale except AttributeError: raise AttributeError("This potential does not have a '_scale' defined to base the concentration on or does not support calculating the virial radius")
[docs] def nemo_accname(self): """ NAME: nemo_accname PURPOSE: return the accname potential name for use of this potential with NEMO INPUT: (none) OUTPUT: Acceleration name HISTORY: 2014-12-18 - Written - Bovy (IAS) """ try: return self._nemo_accname except AttributeError: raise AttributeError('NEMO acceleration name not supported for %s' % self.__class__.__name__)
[docs] def nemo_accpars(self,vo,ro): """ NAME: nemo_accpars PURPOSE: return the accpars potential parameters for use of this potential with NEMO INPUT: vo - velocity unit in km/s ro - length unit in kpc OUTPUT: accpars string HISTORY: 2014-12-18 - Written - Bovy (IAS) """ try: return self._nemo_accpars(vo,ro) except AttributeError: raise AttributeError('NEMO acceleration parameters not supported for %s' % self.__class__.__name__)
[docs] @potential_physical_input @physical_conversion('position',pop=True) def rtide(self,R,z,phi=0.,t=0.,M=None): """ NAME: rtide PURPOSE: Calculate the tidal radius for object of mass M assuming a circular orbit as .. math:: r_t^3 = \\frac{GM_s}{\\Omega^2-\\mathrm{d}^2\\Phi/\\mathrm{d}r^2} where :math:`M_s` is the cluster mass, :math:`\\Omega` is the circular frequency, and :math:`\Phi` is the gravitational potential. For non-spherical potentials, we evaluate :math:`\\Omega^2 = (1/r)(\\mathrm{d}\\Phi/\\mathrm{d}r)` and evaluate the derivatives at the given position of the cluster. INPUT: R - Galactocentric radius (can be Quantity) z - height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) M - (default = None) Mass of object (can be Quantity) OUTPUT: Tidal Radius HISTORY: 2018-03-21 - Written - Webb (UofT) """ if M is None: #Make sure an object mass is given raise PotentialError("Mass parameter M= needs to be set to compute tidal radius") r= numpy.sqrt(R**2.+z**2.) omegac2= -self.rforce(R,z,phi=phi,t=t,use_physical=False)/r d2phidr2= self.r2deriv(R,z,phi=phi,t=t,use_physical=False) return (M/(omegac2-d2phidr2))**(1./3.)
[docs] @potential_physical_input @physical_conversion('forcederivative',pop=True) def ttensor(self,R,z,phi=0.,t=0.,eigenval=False): """ NAME: ttensor PURPOSE: Calculate the tidal tensor Tij=-d(Psi)(dxidxj) INPUT: R - Galactocentric radius (can be Quantity) z - height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) eigenval - return eigenvalues if true (optional; boolean) OUTPUT: Tidal Tensor HISTORY: 2018-03-21 - Written - Webb (UofT) """ if self.isNonAxi: raise PotentialError("Tidal tensor calculation is currently only implemented for axisymmetric potentials") #Evaluate forces, angles and derivatives Rderiv= -self.Rforce(R,z,phi=phi,t=t,use_physical=False) phideriv= -self.phiforce(R,z,phi=phi,t=t,use_physical=False) R2deriv= self.R2deriv(R,z,phi=phi,t=t,use_physical=False) z2deriv= self.z2deriv(R,z,phi=phi,t=t,use_physical=False) phi2deriv= self.phi2deriv(R,z,phi=phi,t=t,use_physical=False) Rzderiv= self.Rzderiv(R,z,phi=phi,t=t,use_physical=False) Rphideriv= self.Rphideriv(R,z,phi=phi,t=t,use_physical=False) #Temporarily set zphideriv to zero until zphideriv is added to Class zphideriv=0.0 cosphi=numpy.cos(phi) sinphi=numpy.sin(phi) cos2phi=cosphi**2.0 sin2phi=sinphi**2.0 R2=R**2.0 R3=R**3.0 # Tidal tensor txx= R2deriv*cos2phi-Rphideriv*2.*cosphi*sinphi/R+Rderiv*sin2phi/R\ +phi2deriv*sin2phi/R2+phideriv*2.*cosphi*sinphi/R2 tyx= R2deriv*sinphi*cosphi+Rphideriv*(cos2phi-sin2phi)/R\ -Rderiv*sinphi*cosphi/R-phi2deriv*sinphi*cosphi/R2\ +phideriv*(sin2phi-cos2phi)/R2 tzx=Rzderiv*cosphi-zphideriv*sinphi/R tyy=R2deriv*sin2phi+Rphideriv*2.*cosphi*sinphi/R+Rderiv*cos2phi/R\ +phi2deriv*cos2phi/R2-phideriv*2.*sinphi*cosphi/R2 txy=tyx tzy=Rzderiv*sinphi+zphideriv*cosphi/R txz=tzx tyz=tzy tzz=z2deriv tij=-numpy.array([[txx,txy,txz],[tyx,tyy,tyz],[tzx,tzy,tzz]]) if eigenval: return numpy.linalg.eigvals(tij) else: return tij
[docs] @physical_conversion('position',pop=True) def zvc(self,R,E,Lz,phi=0.,t=0.): """ NAME: zvc PURPOSE: Calculate the zero-velocity curve: z such that Phi(R,z) + Lz/[2R^2] = E (assumes that F_z(R,z) = negative at positive z such that there is a single solution) INPUT: R - Galactocentric radius (can be Quantity) E - Energy (can be Quantity) Lz - Angular momentum (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: z such that Phi(R,z) + Lz/[2R^2] = E HISTORY: 2020-08-20 - Written - Bovy (UofT) """ return zvc(self,R,E,Lz,phi=phi,t=t,use_physical=False)
[docs] @physical_conversion('position',pop=True) def zvc_range(self,E,Lz,phi=0.,t=0.): """ NAME: zvc_range PURPOSE: Calculate the minimum and maximum radius for which the zero-velocity curve exists for this energy and angular momentum (R such that Phi(R,0) + Lz/[2R^2] = E) INPUT: E - Energy (can be Quantity) Lz - Angular momentum (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: Solutions R such that Phi(R,0) + Lz/[2R^2] = E HISTORY: 2020-08-20 - Written - Bovy (UofT) """ return zvc_range(self,E,Lz,phi=phi,t=t,use_physical=False)
class PotentialError(Exception): #pragma: no cover def __init__(self, value): self.value = value def __str__(self): return repr(self.value)
[docs]@potential_physical_input @physical_conversion('energy',pop=True) def evaluatePotentials(Pot,R,z,phi=None,t=0.,dR=0,dphi=0): """ NAME: evaluatePotentials PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - potential or list of potentials (dissipative forces in such a list are ignored) R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (can be Quantity) t - time (can be Quantity) dR= dphi=, if set to non-zero integers, return the dR, dphi't derivative instead OUTPUT: Phi(R,z) HISTORY: 2010-04-16 - Written - Bovy (NYU) """ return _evaluatePotentials(Pot,R,z,phi=phi,t=t,dR=dR,dphi=dphi)
def _evaluatePotentials(Pot,R,z,phi=None,t=0.,dR=0,dphi=0): """Raw, undecorated function for internal use""" nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") isList= isinstance(Pot,list) if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot._call_nodecorator(R,z,phi=phi,t=t,dR=dR,dphi=dphi) return out elif isinstance(Pot,Potential): return Pot._call_nodecorator(R,z,phi=phi,t=t,dR=dR,dphi=dphi) else: #pragma: no cover raise PotentialError("Input to 'evaluatePotentials' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('density',pop=True) def evaluateDensities(Pot,R,z,phi=None,t=0.,forcepoisson=False): """ NAME: evaluateDensities PURPOSE: convenience function to evaluate a possible sum of densities INPUT: Pot - potential or list of potentials (dissipative forces in such a list are ignored) R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (can be Quantity) t - time (can be Quantity) forcepoisson= if True, calculate the density through the Poisson equation, even if an explicit expression for the density exists OUTPUT: rho(R,z) HISTORY: 2010-08-08 - Written - Bovy (NYU) 2013-12-28 - Added forcepoisson - Bovy (IAS) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.dens(R,z,phi=phi,t=t,forcepoisson=forcepoisson, use_physical=False) return out elif isinstance(Pot,Potential): return Pot.dens(R,z,phi=phi,t=t,forcepoisson=forcepoisson, use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluateDensities' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('surfacedensity',pop=True) def evaluateSurfaceDensities(Pot,R,z,phi=None,t=0.,forcepoisson=False): """ NAME: evaluateSurfaceDensities PURPOSE: convenience function to evaluate a possible sum of surface densities INPUT: Pot - potential or list of potentials (dissipative forces in such a list are ignored) R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (can be Quantity) t - time (can be Quantity) forcepoisson= if True, calculate the surface density through the Poisson equation, even if an explicit expression for the surface density exists OUTPUT: Sigma(R,z) HISTORY: 2018-08-20 - Written - Bovy (UofT) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.surfdens(R,z,phi=phi,t=t,forcepoisson=forcepoisson, use_physical=False) return out elif isinstance(Pot,Potential): return Pot.surfdens(R,z,phi=phi,t=t,forcepoisson=forcepoisson, use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluateSurfaceDensities' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('mass',pop=True) def mass(Pot,R,z=None,t=0.,forceint=False): """ NAME: mass PURPOSE: convenience function to evaluate a possible sum of masses INPUT: Pot - potential or list of potentials (dissipative forces in such a list are ignored) R - cylindrical Galactocentric distance (can be Quantity) z= (None) vertical height up to which to integrate (can be Quantity) t - time (can be Quantity) forceint= if True, calculate the mass through integration of the density, even if an explicit expression for the mass exists OUTPUT: Mass enclosed within the spherical shell with radius R if z is None else mass in the slab <R and between -z and z HISTORY: 2021-02-07 - Written - Bovy (UofT) 2021-03-15 - Changed to integrate to spherical shell for z is None slab otherwise - Bovy (UofT) """ Pot= flatten(Pot) isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi: raise NotImplementedError('mass for non-axisymmetric potentials is not currently supported') if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.mass(R,z=z,t=t,forceint=forceint,use_physical=False) return out elif isinstance(Pot,Potential): return Pot.mass(R,z=z,t=t,forceint=forceint,use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'mass' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('force',pop=True) def evaluateRforces(Pot,R,z,phi=None,t=0.,v=None): """ NAME: evaluateRforce PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity)) t - time (optional; can be Quantity) v - current velocity in cylindrical coordinates (optional, but required when including dissipative forces; can be a Quantity) OUTPUT: F_R(R,z,phi,t) HISTORY: 2010-04-16 - Written - Bovy (NYU) 2018-03-16 - Added velocity input for dissipative forces - Bovy (UofT) """ return _evaluateRforces(Pot,R,z,phi=phi,t=t,v=v)
def _evaluateRforces(Pot,R,z,phi=None,t=0.,v=None): """Raw, undecorated function for internal use""" isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") dissipative= _isDissipative(Pot) if dissipative and v is None: raise PotentialError("The (list of) Potential instances includes dissipative, but you did not provide the 3D velocity (required for dissipative forces") if isList: out= 0. for pot in Pot: if isinstance(pot,DissipativeForce): out+= pot._Rforce_nodecorator(R,z,phi=phi,t=t,v=v) else: out+= pot._Rforce_nodecorator(R,z,phi=phi,t=t) return out elif isinstance(Pot,Potential): return Pot._Rforce_nodecorator(R,z,phi=phi,t=t) elif isinstance(Pot,DissipativeForce): return Pot._Rforce_nodecorator(R,z,phi=phi,t=t,v=v) else: #pragma: no cover raise PotentialError("Input to 'evaluateRforces' is neither a Potential-instance, DissipativeForce-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('energy',pop=True) def evaluatephiforces(Pot,R,z,phi=None,t=0.,v=None): """ NAME: evaluatephiforces PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) v - current velocity in cylindrical coordinates (optional, but required when including dissipative forces; can be a Quantity) OUTPUT: F_phi(R,z,phi,t) HISTORY: 2010-04-16 - Written - Bovy (NYU) 2018-03-16 - Added velocity input for dissipative forces - Bovy (UofT) """ return _evaluatephiforces(Pot,R,z,phi=phi,t=t,v=v)
def _evaluatephiforces(Pot,R,z,phi=None,t=0.,v=None): """Raw, undecorated function for internal use""" isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") dissipative= _isDissipative(Pot) if dissipative and v is None: raise PotentialError("The (list of) Potential instances includes dissipative, but you did not provide the 3D velocity (required for dissipative forces") if isList: out= 0. for pot in Pot: if isinstance(pot,DissipativeForce): out+= pot._phiforce_nodecorator(R,z,phi=phi,t=t,v=v) else: out+= pot._phiforce_nodecorator(R,z,phi=phi,t=t) return out elif isinstance(Pot,Potential): return Pot._phiforce_nodecorator(R,z,phi=phi,t=t) elif isinstance(Pot,DissipativeForce): return Pot._phiforce_nodecorator(R,z,phi=phi,t=t,v=v) else: #pragma: no cover raise PotentialError("Input to 'evaluatephiforces' is neither a Potential-instance, DissipativeForce-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('force',pop=True) def evaluatezforces(Pot,R,z,phi=None,t=0.,v=None): """ NAME: evaluatezforces PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) v - current velocity in cylindrical coordinates (optional, but required when including dissipative forces; can be a Quantity) OUTPUT: F_z(R,z,phi,t) HISTORY: 2010-04-16 - Written - Bovy (NYU) 2018-03-16 - Added velocity input for dissipative forces - Bovy (UofT) """ return _evaluatezforces(Pot,R,z,phi=phi,t=t,v=v)
def _evaluatezforces(Pot,R,z,phi=None,t=0.,v=None): """Raw, undecorated function for internal use""" isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") dissipative= _isDissipative(Pot) if dissipative and v is None: raise PotentialError("The (list of) Potential instances includes dissipative, but you did not provide the 3D velocity (required for dissipative forces") if isList: out= 0. for pot in Pot: if isinstance(pot,DissipativeForce): out+= pot._zforce_nodecorator(R,z,phi=phi,t=t,v=v) else: out+= pot._zforce_nodecorator(R,z,phi=phi,t=t) return out elif isinstance(Pot,Potential): return Pot._zforce_nodecorator(R,z,phi=phi,t=t) elif isinstance(Pot,DissipativeForce): return Pot._zforce_nodecorator(R,z,phi=phi,t=t,v=v) else: #pragma: no cover raise PotentialError("Input to 'evaluatezforces' is neither a Potential-instance, DissipativeForce-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('force',pop=True) def evaluaterforces(Pot,R,z,phi=None,t=0.,v=None): """ NAME: evaluaterforces PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) v - current velocity in cylindrical coordinates (optional, but required when including dissipative forces; can be a Quantity) OUTPUT: F_r(R,z,phi,t) HISTORY: 2016-06-10 - Written - Bovy (UofT) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") dissipative= _isDissipative(Pot) if dissipative and v is None: raise PotentialError("The (list of) Potential instances includes dissipative, but you did not provide the 3D velocity (required for dissipative forces") if isList: out= 0. for pot in Pot: if isinstance(pot,DissipativeForce): out+= pot.rforce(R,z,phi=phi,t=t,v=v,use_physical=False) else: out+= pot.rforce(R,z,phi=phi,t=t,use_physical=False) return out elif isinstance(Pot,Potential): return Pot.rforce(R,z,phi=phi,t=t,use_physical=False) elif isinstance(Pot,DissipativeForce): return Pot.rforce(R,z,phi=phi,t=t,v=v,use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluaterforces' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('forcederivative',pop=True) def evaluateR2derivs(Pot,R,z,phi=None,t=0.): """ NAME: evaluateR2derivs PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials (dissipative forces in such a list are ignored) R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: d2Phi/d2R(R,z,phi,t) HISTORY: 2012-07-25 - Written - Bovy (IAS) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.R2deriv(R,z,phi=phi,t=t,use_physical=False) return out elif isinstance(Pot,Potential): return Pot.R2deriv(R,z,phi=phi,t=t,use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluateR2derivs' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('forcederivative',pop=True) def evaluatez2derivs(Pot,R,z,phi=None,t=0.): """ NAME: evaluatez2derivs PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials (dissipative forces in such a list are ignored) R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: d2Phi/d2z(R,z,phi,t) HISTORY: 2012-07-25 - Written - Bovy (IAS) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.z2deriv(R,z,phi=phi,t=t,use_physical=False) return out elif isinstance(Pot,Potential): return Pot.z2deriv(R,z,phi=phi,t=t,use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluatez2derivs' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('forcederivative',pop=True) def evaluateRzderivs(Pot,R,z,phi=None,t=0.): """ NAME: evaluateRzderivs PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials (dissipative forces in such a list are ignored) R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: d2Phi/dz/dR(R,z,phi,t) HISTORY: 2013-08-28 - Written - Bovy (IAS) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.Rzderiv(R,z,phi=phi,t=t,use_physical=False) return out elif isinstance(Pot,Potential): return Pot.Rzderiv(R,z,phi=phi,t=t,use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluateRzderivs' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('energy',pop=True) def evaluatephi2derivs(Pot,R,z,phi=None,t=0.): """ NAME: evaluatephi2derivs PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: d2Phi/d2phi(R,z,phi,t) HISTORY: 2018-03-28 - Written - Bovy (UofT) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.phi2deriv(R,z,phi=phi,t=t,use_physical=False) return out elif isinstance(Pot,Potential): return Pot.phi2deriv(R,z,phi=phi,t=t,use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluatephi2derivs' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('force',pop=True) def evaluateRphiderivs(Pot,R,z,phi=None,t=0.): """ NAME: evaluateRphiderivs PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: d2Phi/dRdphi(R,z,phi,t) HISTORY: 2014-06-30 - Written - Bovy (IAS) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.Rphideriv(R,z,phi=phi,t=t,use_physical=False) return out elif isinstance(Pot,Potential): return Pot.Rphideriv(R,z,phi=phi,t=t,use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluateRphiderivs' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('force',pop=True) def evaluatephizderivs(Pot,R,z,phi=None,t=0.): """ NAME: evaluatephizderivs PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: d2Phi/dphi/dz(R,z,phi,t) HISTORY: 2021-04-30 - Written - Bovy (UofT) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.phizderiv(R,z,phi=phi,t=t,use_physical=False) return out elif isinstance(Pot,Potential): return Pot.phizderiv(R,z,phi=phi,t=t,use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluatephizderivs' is neither a Potential-instance or a list of such instances")
[docs]@potential_physical_input @physical_conversion('forcederivative',pop=True) def evaluater2derivs(Pot,R,z,phi=None,t=0.): """ NAME: evaluater2derivs PURPOSE: convenience function to evaluate a possible sum of potentials INPUT: Pot - a potential or list of potentials R - cylindrical Galactocentric distance (can be Quantity) z - distance above the plane (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: d2phi/dr2(R,z,phi,t) HISTORY: 2018-03-28 - Written - Bovy (UofT) """ isList= isinstance(Pot,list) nonAxi= _isNonAxi(Pot) if nonAxi and phi is None: raise PotentialError("The (list of) Potential instances is non-axisymmetric, but you did not provide phi") if isList: out= 0. for pot in Pot: if not isinstance(pot,DissipativeForce): out+= pot.r2deriv(R,z,phi=phi,t=t,use_physical=False) return out elif isinstance(Pot,Potential): return Pot.r2deriv(R,z,phi=phi,t=t,use_physical=False) else: #pragma: no cover raise PotentialError("Input to 'evaluater2derivs' is neither a Potential-instance or a list of such instances")
[docs]def plotPotentials(Pot,rmin=0.,rmax=1.5,nrs=21,zmin=-0.5,zmax=0.5,nzs=21, phi=None,xy=False,t=0.,effective=False,Lz=None, ncontours=21,savefilename=None,aspect=None, justcontours=False,levels=None,cntrcolors=None): """ NAME: plotPotentials PURPOSE: plot a set of potentials INPUT: Pot - Potential or list of Potential instances rmin= minimum R (can be Quantity) [xmin if xy] rmax= maximum R (can be Quantity) [ymax if xy] nrs= grid in R zmin= minimum z (can be Quantity) [ymin if xy] zmax= maximum z (can be Quantity) [ymax if xy] nzs= grid in z phi= (None) azimuth to use for non-axisymmetric potentials t= (0.) time to use to evaluate potential xy= (False) if True, plot the potential in X-Y effective= (False) if True, plot the effective potential Phi + Lz^2/2/R^2 Lz= (None) angular momentum to use for the effective potential when effective=True justcontours= (False) if True, just plot contours levels= (None) contours to plot ncontours - number of contours when levels is None cntrcolors= (None) colors of the contours (single color or array with length ncontours) savefilename= save to or restore from this savefile (pickle) OUTPUT: plot to output device HISTORY: 2010-07-09 - Written - Bovy (NYU) """ Pot= flatten(Pot) rmin= conversion.parse_length(rmin,**get_physical(Pot)) rmax= conversion.parse_length(rmax,**get_physical(Pot)) zmin= conversion.parse_length(zmin,**get_physical(Pot)) zmax= conversion.parse_length(zmax,**get_physical(Pot)) if not savefilename == None and os.path.exists(savefilename): print("Restoring savefile "+savefilename+" ...") savefile= open(savefilename,'rb') potRz= pickle.load(savefile) Rs= pickle.load(savefile) zs= pickle.load(savefile) savefile.close() else: if effective and Lz is None: raise RuntimeError("When effective=True, you need to specify Lz=") Rs= numpy.linspace(rmin,rmax,nrs) zs= numpy.linspace(zmin,zmax,nzs) potRz= numpy.zeros((nrs,nzs)) for ii in range(nrs): for jj in range(nzs): if xy: R,phi,z= coords.rect_to_cyl(Rs[ii],zs[jj],0.) else: R,z= Rs[ii], zs[jj] potRz[ii,jj]= evaluatePotentials(Pot,numpy.fabs(R), z,phi=phi,t=t, use_physical=False) if effective: potRz[ii,:]+= 0.5*Lz**2/Rs[ii]**2. if not savefilename == None: print("Writing savefile "+savefilename+" ...") savefile= open(savefilename,'wb') pickle.dump(potRz,savefile) pickle.dump(Rs,savefile) pickle.dump(zs,savefile) savefile.close() if aspect is None: aspect=.75*(rmax-rmin)/(zmax-zmin) if xy: xlabel= r'$x/R_0$' ylabel= r'$y/R_0$' else: xlabel=r"$R/R_0$" ylabel=r"$z/R_0$" if levels is None: levels= numpy.linspace(numpy.nanmin(potRz),numpy.nanmax(potRz),ncontours) if cntrcolors is None: cntrcolors= 'k' return plot.dens2d(potRz.T,origin='lower',cmap='gist_gray',contours=True, xlabel=xlabel,ylabel=ylabel, aspect=aspect, xrange=[rmin,rmax], yrange=[zmin,zmax], cntrls='-', justcontours=justcontours, levels=levels,cntrcolors=cntrcolors)
[docs]def plotDensities(Pot,rmin=0.,rmax=1.5,nrs=21,zmin=-0.5,zmax=0.5,nzs=21, phi=None,xy=False,t=0., ncontours=21,savefilename=None,aspect=None,log=False, justcontours=False,**kwargs): """ NAME: plotDensities PURPOSE: plot the density a set of potentials INPUT: Pot - Potential or list of Potential instances rmin= minimum R (can be Quantity) [xmin if xy] rmax= maximum R (can be Quantity) [ymax if xy] nrs= grid in R zmin= minimum z (can be Quantity) [ymin if xy] zmax= maximum z (can be Quantity) [ymax if xy] nzs= grid in z phi= (None) azimuth to use for non-axisymmetric potentials t= (0.) time to use to evaluate potential xy= (False) if True, plot the density in X-Y ncontours= number of contours justcontours= (False) if True, just plot contours savefilename= save to or restore from this savefile (pickle) log= if True, plot the log density OUTPUT: plot to output device HISTORY: 2013-07-05 - Written - Bovy (IAS) """ Pot= flatten(Pot) rmin= conversion.parse_length(rmin,**get_physical(Pot)) rmax= conversion.parse_length(rmax,**get_physical(Pot)) zmin= conversion.parse_length(zmin,**get_physical(Pot)) zmax= conversion.parse_length(zmax,**get_physical(Pot)) if not savefilename == None and os.path.exists(savefilename): print("Restoring savefile "+savefilename+" ...") savefile= open(savefilename,'rb') potRz= pickle.load(savefile) Rs= pickle.load(savefile) zs= pickle.load(savefile) savefile.close() else: Rs= numpy.linspace(rmin,rmax,nrs) zs= numpy.linspace(zmin,zmax,nzs) potRz= numpy.zeros((nrs,nzs)) for ii in range(nrs): for jj in range(nzs): if xy: R,phi,z= coords.rect_to_cyl(Rs[ii],zs[jj],0.) else: R,z= Rs[ii], zs[jj] potRz[ii,jj]= evaluateDensities(Pot,numpy.fabs(R),z,phi=phi, t=t, use_physical=False) if not savefilename == None: print("Writing savefile "+savefilename+" ...") savefile= open(savefilename,'wb') pickle.dump(potRz,savefile) pickle.dump(Rs,savefile) pickle.dump(zs,savefile) savefile.close() if aspect is None: aspect=.75*(rmax-rmin)/(zmax-zmin) if log: potRz= numpy.log(potRz) if xy: xlabel= r'$x/R_0$' ylabel= r'$y/R_0$' else: xlabel=r"$R/R_0$" ylabel=r"$z/R_0$" return plot.dens2d(potRz.T,origin='lower', cmap='gist_yarg',contours=True, xlabel=xlabel,ylabel=ylabel, aspect=aspect, xrange=[rmin,rmax], yrange=[zmin,zmax], cntrls=kwargs.pop('cntrls','-'), justcontours=justcontours, levels=numpy.linspace(numpy.nanmin(potRz),numpy.nanmax(potRz), ncontours), **kwargs)
[docs]def plotSurfaceDensities(Pot, xmin=-1.5,xmax=1.5,nxs=21,ymin=-1.5,ymax=1.5,nys=21, z=numpy.inf,t=0., ncontours=21,savefilename=None,aspect=None, log=False,justcontours=False,**kwargs): """ NAME: plotSurfaceDensities PURPOSE: plot the surface density a set of potentials INPUT: Pot - Potential or list of Potential instances xmin= minimum x (can be Quantity) xmax= maximum x (can be Quantity) nxs= grid in x ymin= minimum y (can be Quantity) ymax= maximum y (can be Quantity) nys= grid in y z= (inf) height between which to integrate the density (from -z to z; can be a Quantity) t= (0.) time to use to evaluate potential ncontours= number of contours justcontours= (False) if True, just plot contours savefilename= save to or restore from this savefile (pickle) log= if True, plot the log density OUTPUT: plot to output device HISTORY: 2020-08-19 - Written - Bovy (UofT) """ Pot= flatten(Pot) xmin= conversion.parse_length(xmin,**get_physical(Pot)) xmax= conversion.parse_length(xmax,**get_physical(Pot)) ymin= conversion.parse_length(ymin,**get_physical(Pot)) ymax= conversion.parse_length(ymax,**get_physical(Pot)) if not savefilename == None and os.path.exists(savefilename): print("Restoring savefile "+savefilename+" ...") savefile= open(savefilename,'rb') surfxy= pickle.load(savefile) xs= pickle.load(savefile) ys= pickle.load(savefile) savefile.close() else: xs= numpy.linspace(xmin,xmax,nxs) ys= numpy.linspace(ymin,ymax,nys) surfxy= numpy.zeros((nxs,nys)) for ii in range(nxs): for jj in range(nys): R,phi,_= coords.rect_to_cyl(xs[ii],ys[jj],0.) surfxy[ii,jj]= evaluateSurfaceDensities(Pot, numpy.fabs(R),z, phi=phi, t=t, use_physical=False) if not savefilename == None: print("Writing savefile "+savefilename+" ...") savefile= open(savefilename,'wb') pickle.dump(surfxy,savefile) pickle.dump(xs,savefile) pickle.dump(ys,savefile) savefile.close() if aspect is None: aspect= 1. if log: surfxy= numpy.log(surfxy) xlabel= r'$x/R_0$' ylabel= r'$y/R_0$' return plot.dens2d(surfxy.T,origin='lower', cmap='gist_yarg',contours=True, xlabel=xlabel,ylabel=ylabel, aspect=aspect, xrange=[xmin,xmax], yrange=[ymin,ymax], cntrls=kwargs.pop('cntrls','-'), justcontours=justcontours, levels=numpy.linspace(numpy.nanmin(surfxy), numpy.nanmax(surfxy), ncontours), **kwargs)
[docs]@potential_physical_input @physical_conversion('frequency',pop=True) def epifreq(Pot,R,t=0.): """ NAME: epifreq PURPOSE: calculate the epicycle frequency at R in the potential Pot INPUT: Pot - Potential instance or list thereof R - Galactocentric radius (can be Quantity) t - time (optional; can be Quantity) OUTPUT: epicycle frequency HISTORY: 2012-07-25 - Written - Bovy (IAS) """ from .planarPotential import planarPotential if isinstance(Pot,(Potential,planarPotential)): return Pot.epifreq(R,t=t,use_physical=False) from ..potential import evaluateplanarRforces, evaluateplanarR2derivs from ..potential import PotentialError try: return numpy.sqrt(evaluateplanarR2derivs(Pot,R,t=t,use_physical=False) -3./R*evaluateplanarRforces(Pot,R,t=t,use_physical=False)) except PotentialError: from ..potential import RZToplanarPotential Pot= RZToplanarPotential(Pot) return numpy.sqrt(evaluateplanarR2derivs(Pot,R,t=t,use_physical=False) -3./R*evaluateplanarRforces(Pot,R,t=t,use_physical=False))
[docs]@potential_physical_input @physical_conversion('frequency',pop=True) def verticalfreq(Pot,R,t=0.): """ NAME: verticalfreq PURPOSE: calculate the vertical frequency at R in the potential Pot INPUT: Pot - Potential instance or list thereof R - Galactocentric radius (can be Quantity) t - time (optional; can be Quantity) OUTPUT: vertical frequency HISTORY: 2012-07-25 - Written - Bovy (IAS@MPIA) """ from .planarPotential import planarPotential if isinstance(Pot,(Potential,planarPotential)): return Pot.verticalfreq(R,t=t,use_physical=False) return numpy.sqrt(evaluatez2derivs(Pot,R,0.,t=t,use_physical=False))
[docs]@potential_physical_input @physical_conversion('dimensionless',pop=True) def flattening(Pot,R,z,t=0.): """ NAME: flattening PURPOSE: calculate the potential flattening, defined as sqrt(fabs(z/R F_R/F_z)) INPUT: Pot - Potential instance or list thereof R - Galactocentric radius (can be Quantity) z - height (can be Quantity) t - time (optional; can be Quantity) OUTPUT: flattening HISTORY: 2012-09-13 - Written - Bovy (IAS) """ return numpy.sqrt(numpy.fabs(z/R*evaluateRforces(Pot,R,z,t=t,use_physical=False)\ /evaluatezforces(Pot,R,z,t=t,use_physical=False)))
[docs]@physical_conversion('velocity',pop=True) def vterm(Pot,l,t=0.,deg=True): """ NAME: vterm PURPOSE: calculate the terminal velocity at l in this potential INPUT: Pot - Potential instance l - Galactic longitude [deg/rad; can be Quantity) t - time (optional; can be Quantity) deg= if True (default), l in deg OUTPUT: terminal velocity HISTORY: 2013-05-31 - Written - Bovy (IAS) """ Pot= flatten(Pot) if _APY_LOADED and isinstance(l,units.Quantity): l= conversion.parse_angle(l) deg= False if deg: sinl= numpy.sin(l/180.*numpy.pi) else: sinl= numpy.sin(l) return sinl*(omegac(Pot,sinl,t=t,use_physical=False) -omegac(Pot,1.,t=t,use_physical=False))
[docs]@physical_conversion('position',pop=True) def rl(Pot,lz,t=0.): """ NAME: rl PURPOSE: calculate the radius of a circular orbit of Lz INPUT: Pot - Potential instance or list thereof lz - Angular momentum (can be Quantity) t - time (optional; can be Quantity) OUTPUT: radius HISTORY: 2012-07-30 - Written - Bovy (IAS@MPIA) NOTE: An efficient way to call this function on many objects is provided as the Orbit method rguiding """ Pot= flatten(Pot) lz= conversion.parse_angmom(lz,**conversion.get_physical(Pot)) #Find interval rstart= _rlFindStart(numpy.fabs(lz),#assumes vo=1. numpy.fabs(lz), Pot, t=t) try: return optimize.brentq(_rlfunc,10.**-5.,rstart, args=(numpy.fabs(lz), Pot, t), maxiter=200,disp=False) except ValueError: #Probably lz small and starting lz to great rlower= _rlFindStart(10.**-5., numpy.fabs(lz), Pot,t=t,lower=True) return optimize.brentq(_rlfunc,rlower,rstart, args=(numpy.fabs(lz), Pot,t))
def _rlfunc(rl,lz,pot,t=0.): """Function that gives rvc-lz""" thisvcirc= vcirc(pot,rl,t=t,use_physical=False) return rl*thisvcirc-lz def _rlFindStart(rl,lz,pot,t=0.,lower=False): """find a starting interval for rl""" rtry= 2.*rl while (2.*lower-1.)*_rlfunc(rtry,lz,pot,t=t) > 0.: if lower: rtry/= 2. else: rtry*= 2. return rtry
[docs]@physical_conversion('position',pop=True) def rE(Pot,E,t=0.): """ NAME: rE PURPOSE: calculate the radius of a circular orbit with energy E INPUT: Pot - Potential instance or list thereof E - Energy (can be Quantity) t - time (optional; can be Quantity) OUTPUT: radius HISTORY: 2022-04-06 - Written - Bovy (UofT) NOTE: An efficient way to call this function on many objects is provided as the Orbit method rE """ Pot= flatten(Pot) E= conversion.parse_energy(E,**conversion.get_physical(Pot)) #Find interval rstart= _rEFindStart(1.,E,Pot,t=t) try: return optimize.brentq(_rEfunc,10.**-5.,rstart, args=(E,Pot,t), maxiter=200,disp=False) except ValueError: #Probably E small and starting rE to great rlower= _rEFindStart(10.**-5.,E,Pot,t=t,lower=True) return optimize.brentq(_rEfunc,rlower,rstart, args=(E,Pot,t))
def _rEfunc(rE,E,pot,t=0.): """Function that gives vc^2/2+Pot(rc)-E""" thisvcirc= vcirc(pot,rE,t=t,use_physical=False) return thisvcirc**2./2.+_evaluatePotentials(pot,rE,0.,t=t)-E def _rEFindStart(rE,E,pot,t=0.,lower=False): """find a starting interval for rE""" rtry= 2.*rE while (2.*lower-1.)*_rEfunc(rtry,E,pot,t=t) > 0.: if lower: rtry/= 2. else: rtry*= 2. return rtry
[docs]@physical_conversion('action',pop=True) def LcE(Pot,E,t=0.): """ NAME: LcE PURPOSE: calculate the angular momentum of a circular orbit with energy E INPUT: Pot - Potential instance or list thereof E - Energy (can be Quantity) t - time (optional; can be Quantity) OUTPUT: Lc(E) HISTORY: 2022-04-06 - Written - Bovy (UofT) """ thisrE= rE(Pot,E,t=t,use_physical=False) return thisrE*vcirc(Pot,thisrE,use_physical=False)
[docs]@physical_conversion('position',pop=True) def lindbladR(Pot,OmegaP,m=2,t=0.,**kwargs): """ NAME: lindbladR PURPOSE: calculate the radius of a Lindblad resonance INPUT: Pot - Potential instance or list of such instances OmegaP - pattern speed (can be Quantity) m= order of the resonance (as in m(O-Op)=kappa (negative m for outer) use m='corotation' for corotation +scipy.optimize.brentq xtol,rtol,maxiter kwargs t - time (optional; can be Quantity) OUTPUT: radius of Linblad resonance, None if there is no resonance HISTORY: 2011-10-09 - Written - Bovy (IAS) """ Pot= flatten(Pot) OmegaP= conversion.parse_frequency(OmegaP,**conversion.get_physical(Pot)) if isinstance(m,str): if 'corot' in m.lower(): corotation= True else: raise IOError("'m' input not recognized, should be an integer or 'corotation'") else: corotation= False if corotation: try: out= optimize.brentq(_corotationR_eq,0.0000001,1000., args=(Pot,OmegaP,t),**kwargs) except ValueError: try: # Sometimes 0.0000001 is numerically too small to start... out= optimize.brentq(_corotationR_eq,0.01,1000., args=(Pot,OmegaP,t),**kwargs) except ValueError: return None except RuntimeError: #pragma: no cover raise return out else: try: out= optimize.brentq(_lindbladR_eq,0.0000001,1000., args=(Pot,OmegaP,m,t),**kwargs) except ValueError: return None except RuntimeError: #pragma: no cover raise return out
def _corotationR_eq(R,Pot,OmegaP,t=0.): return omegac(Pot,R,t=t,use_physical=False)-OmegaP def _lindbladR_eq(R,Pot,OmegaP,m,t=0.): return m*(omegac(Pot,R,t=t,use_physical=False)-OmegaP)\ -epifreq(Pot,R,t=t,use_physical=False)
[docs]@potential_physical_input @physical_conversion('frequency',pop=True) def omegac(Pot,R,t=0.): """ NAME: omegac PURPOSE: calculate the circular angular speed velocity at R in potential Pot INPUT: Pot - Potential instance or list of such instances R - Galactocentric radius (can be Quantity) t - time (optional; can be Quantity) OUTPUT: circular angular speed HISTORY: 2011-10-09 - Written - Bovy (IAS) """ from ..potential import evaluateplanarRforces try: return numpy.sqrt(-evaluateplanarRforces(Pot,R,t=t,use_physical=False)/R) except PotentialError: from ..potential import RZToplanarPotential Pot= RZToplanarPotential(Pot) return numpy.sqrt(-evaluateplanarRforces(Pot,R,t=t,use_physical=False)/R)
[docs]def nemo_accname(Pot): """ NAME: nemo_accname PURPOSE: return the accname potential name for use of this potential or list of potentials with NEMO INPUT: Pot - Potential instance or list of such instances OUTPUT: Acceleration name in the correct format to give to accname= HISTORY: 2014-12-18 - Written - Bovy (IAS) """ Pot= flatten(Pot) if isinstance(Pot,list): out= '' for ii,pot in enumerate(Pot): if ii > 0: out+= '+' out+= pot.nemo_accname() return out elif isinstance(Pot,Potential): return Pot.nemo_accname() else: #pragma: no cover raise PotentialError("Input to 'nemo_accname' is neither a Potential-instance or a list of such instances")
[docs]def nemo_accpars(Pot,vo,ro): """ NAME: nemo_accpars PURPOSE: return the accpars potential parameters for use of this potential or list of potentials with NEMO INPUT: Pot - Potential instance or list of such instances vo - velocity unit in km/s ro - length unit in kpc OUTPUT: accpars string in the corrct format to give to accpars HISTORY: 2014-12-18 - Written - Bovy (IAS) """ Pot= flatten(Pot) if isinstance(Pot,list): out= '' for ii,pot in enumerate(Pot): if ii > 0: out+= '#' out+= pot.nemo_accpars(vo,ro) return out elif isinstance(Pot,Potential): return Pot.nemo_accpars(vo,ro) else: #pragma: no cover raise PotentialError("Input to 'nemo_accpars' is neither a Potential-instance or a list of such instances")
[docs]def to_amuse(Pot,t=0.,tgalpy=0.,reverse=False,ro=None,vo=None): # pragma: no cover """ NAME: to_amuse PURPOSE: Return an AMUSE representation of a galpy Potential or list of Potentials INPUT: Pot - Potential instance or list of such instances t= (0.) Initial time in AMUSE (can be in internal galpy units or AMUSE units) tgalpy= (0.) Initial time in galpy (can be in internal galpy units or AMUSE units); because AMUSE initial times have to be positive, this is useful to set if the initial time in galpy is negative reverse= (False) set whether the galpy potential evolves forwards or backwards in time (default: False); because AMUSE can only integrate forward in time, this is useful to integrate backward in time in AMUSE ro= (default taken from Pot) length unit in kpc vo= (default taken from Pot) velocity unit in km/s OUTPUT: AMUSE representation of Pot HISTORY: 2019-08-04 - Written - Bovy (UofT) 2019-08-12 - Implemented actual function - Webb (UofT) """ try: from . import amuse except ImportError: raise ImportError("To obtain an AMUSE representation of a galpy potential, you need to have AMUSE installed") Pot= flatten(Pot) if ro is None or vo is None: physical_dict= get_physical(Pot) if ro is None: ro= physical_dict.get('ro') if vo is None: vo= physical_dict.get('vo') return amuse.galpy_profile(Pot,t=t,tgalpy=tgalpy,ro=ro,vo=vo)
[docs]def turn_physical_off(Pot): """ NAME: turn_physical_off PURPOSE: turn off automatic returning of outputs in physical units INPUT: (none) OUTPUT: (none) HISTORY: 2016-01-30 - Written - Bovy (UofT) """ if isinstance(Pot,list): for pot in Pot: turn_physical_off(pot) else: Pot.turn_physical_off() return None
[docs]def turn_physical_on(Pot,ro=None,vo=None): """ NAME: turn_physical_on PURPOSE: turn on automatic returning of outputs in physical units INPUT: ro= reference distance (kpc; can be Quantity) vo= reference velocity (km/s; can be Quantity) OUTPUT: (none) HISTORY: 2016-01-30 - Written - Bovy (UofT) """ if isinstance(Pot,list): for pot in Pot: turn_physical_on(pot,ro=ro,vo=vo) else: Pot.turn_physical_on(ro=ro,vo=vo) return None
def _flatten_list(L): for item in L: try: for i in _flatten_list(item): yield i except TypeError: yield item
[docs]def flatten(Pot): """ NAME: flatten PURPOSE: flatten a possibly nested list of Potential instances into a flat list INPUT: Pot - list (possibly nested) of Potential instances OUTPUT: Flattened list of Potential instances HISTORY: 2018-03-14 - Written - Bovy (UofT) """ if isinstance(Pot, Potential): return Pot elif isinstance(Pot, list): return list(_flatten_list(Pot)) else: return Pot
def _check_c(Pot,dxdv=False,dens=False): """ NAME: _check_c PURPOSE: check whether a potential or list thereof has a C implementation INPUT: Pot - Potential instance or list of such instances dxdv= (False) check whether the potential has dxdv implementation dens= (False) check whether the potential has its density implemented in C OUTPUT: True if a C implementation exists, False otherwise HISTORY: 2014-02-17 - Written - Bovy (IAS) 2017-07-01 - Generalized to dxdv, added general support for WrapperPotentials, and added support for planarPotentials """ Pot= flatten(Pot) from ..potential import planarPotential, linearPotential if dxdv: hasC_attr= 'hasC_dxdv' elif dens: hasC_attr= 'hasC_dens' else: hasC_attr= 'hasC' from .WrapperPotential import parentWrapperPotential if isinstance(Pot,list): return numpy.all(numpy.array([_check_c(p,dxdv=dxdv,dens=dens) for p in Pot], dtype='bool')) elif isinstance(Pot,parentWrapperPotential): return bool(Pot.__dict__[hasC_attr]*_check_c(Pot._pot)) elif isinstance(Pot,Force) or isinstance(Pot,planarPotential) \ or isinstance(Pot,linearPotential): return Pot.__dict__[hasC_attr] def _dim(Pot): """ NAME: _dim PURPOSE: Determine the dimensionality of this potential INPUT: Pot - Potential instance or list of such instances OUTPUT: Minimum of the dimensionality of all potentials if list; otherwise Pot.dim HISTORY: 2016-04-19 - Written - Bovy (UofT) """ from ..potential import planarPotential, linearPotential if isinstance(Pot,list): return numpy.amin(numpy.array([_dim(p) for p in Pot],dtype='int')) elif isinstance(Pot,(Potential,planarPotential,linearPotential, DissipativeForce)): return Pot.dim def _isNonAxi(Pot): """ NAME: _isNonAxi PURPOSE: Determine whether this potential is non-axisymmetric INPUT: Pot - Potential instance or list of such instances OUTPUT: True or False depending on whether the potential is non-axisymmetric (note that some potentials might return True, even though for some parameter values they are axisymmetric) HISTORY: 2016-06-16 - Written - Bovy (UofT) """ isList= isinstance(Pot,list) if isList: isAxis= [not _isNonAxi(p) for p in Pot] nonAxi= not numpy.prod(numpy.array(isAxis)) else: nonAxi= Pot.isNonAxi return nonAxi def kms_to_kpcGyrDecorator(func): """Decorator to convert velocities from km/s to kpc/Gyr""" @wraps(func) def kms_to_kpcGyr_wrapper(*args,**kwargs): return func(args[0],velocity_in_kpcGyr(args[1],1.),args[2],**kwargs) return kms_to_kpcGyr_wrapper
[docs]@potential_physical_input @physical_conversion('position',pop=True) def rtide(Pot,R,z,phi=0.,t=0.,M=None): """ NAME: rtide PURPOSE: Calculate the tidal radius for object of mass M assuming a circular orbit as .. math:: r_t^3 = \\frac{GM_s}{\\Omega^2-\\mathrm{d}^2\\Phi/\\mathrm{d}r^2} where :math:`M_s` is the cluster mass, :math:`\\Omega` is the circular frequency, and :math:`\Phi` is the gravitational potential. For non-spherical potentials, we evaluate :math:`\\Omega^2 = (1/r)(\\mathrm{d}\\Phi/\\mathrm{d}r)` and evaluate the derivatives at the given position of the cluster. INPUT: Pot - Potential instance or list of such instances R - Galactocentric radius (can be Quantity) z - height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) M - (default = None) Mass of object (can be Quantity) OUTPUT: Tidal Radius HISTORY: 2018-03-21 - Written - Webb (UofT) """ Pot= flatten(Pot) if M is None: #Make sure an object mass is given raise PotentialError("Mass parameter M= needs to be set to compute tidal radius") r= numpy.sqrt(R**2.+z**2.) omegac2=-evaluaterforces(Pot,R,z,phi=phi,t=t,use_physical=False)/r d2phidr2= evaluater2derivs(Pot,R,z,phi=phi,t=t,use_physical=False) return (M/(omegac2-d2phidr2))**(1./3.)
[docs]@potential_physical_input @physical_conversion('forcederivative',pop=True) def ttensor(Pot,R,z,phi=0.,t=0.,eigenval=False): """ NAME: ttensor PURPOSE: Calculate the tidal tensor Tij=-d(Psi)(dxidxj) INPUT: Pot - Potential instance or list of such instances R - Galactocentric radius (can be Quantity) z - height (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) eigenval - return eigenvalues if true (optional; boolean) OUTPUT: Tidal Tensor HISTORY: 2018-03-21 - Written - Webb (UofT) """ Pot= flatten(Pot) if _isNonAxi(Pot): raise PotentialError("Tidal tensor calculation is currently only implemented for axisymmetric potentials") #Evaluate forces, angles and derivatives Rderiv= -evaluateRforces(Pot,R,z,phi=phi,t=t,use_physical=False) phideriv= -evaluatephiforces(Pot,R,z,phi=phi,t=t,use_physical=False) R2deriv= evaluateR2derivs(Pot,R,z,phi=phi,t=t,use_physical=False) z2deriv= evaluatez2derivs(Pot,R,z,phi=phi,t=t,use_physical=False) phi2deriv= evaluatephi2derivs(Pot,R,z,phi=phi,t=t,use_physical=False) Rzderiv= evaluateRzderivs(Pot,R,z,phi=phi,t=t,use_physical=False) Rphideriv= evaluateRphiderivs(Pot,R,z,phi=phi,t=t,use_physical=False) #Temporarily set zphideriv to zero until zphideriv is added to Class zphideriv=0.0 cosphi=numpy.cos(phi) sinphi=numpy.sin(phi) cos2phi=cosphi**2.0 sin2phi=sinphi**2.0 R2=R**2.0 R3=R**3.0 # Tidal tensor txx= R2deriv*cos2phi-Rphideriv*2.*cosphi*sinphi/R+Rderiv*sin2phi/R\ +phi2deriv*sin2phi/R2+phideriv*2.*cosphi*sinphi/R2 tyx= R2deriv*sinphi*cosphi+Rphideriv*(cos2phi-sin2phi)/R\ -Rderiv*sinphi*cosphi/R-phi2deriv*sinphi*cosphi/R2+phideriv*(sin2phi-cos2phi)/R2 tzx= Rzderiv*cosphi-zphideriv*sinphi/R tyy= R2deriv*sin2phi+Rphideriv*2.*cosphi*sinphi/R+Rderiv*cos2phi/R\ +phi2deriv*cos2phi/R2-phideriv*2.*sinphi*cosphi/R2 txy=tyx tzy= Rzderiv*sinphi+zphideriv*cosphi/R txz= tzx tyz= tzy tzz=z2deriv tij= -numpy.array([[txx,txy,txz],[tyx,tyy,tyz],[tzx,tzy,tzz]]) if eigenval: return numpy.linalg.eigvals(tij) else: return tij
[docs]@physical_conversion('position',pop=True) def zvc(Pot,R,E,Lz,phi=0.,t=0.): """ NAME: zvc PURPOSE: Calculate the zero-velocity curve: z such that Phi(R,z) + Lz/[2R^2] = E (assumes that F_z(R,z) = negative at positive z such that there is a single solution) INPUT: Pot - Potential instance or list of such instances R - Galactocentric radius (can be Quantity) E - Energy (can be Quantity) Lz - Angular momentum (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: z such that Phi(R,z) + Lz/[2R^2] = E HISTORY: 2020-08-20 - Written - Bovy (UofT) """ Pot= flatten(Pot) R= conversion.parse_length(R,**get_physical(Pot)) E= conversion.parse_energy(E,**get_physical(Pot)) Lz= conversion.parse_angmom(Lz,**get_physical(Pot)) Lz2over2R2= Lz**2./2./R**2. # Check z=0 and whether a solution exists if numpy.fabs(_evaluatePotentials(Pot,R,0.,phi=phi,t=t)+Lz2over2R2-E) < 1e-8: return 0. elif _evaluatePotentials(Pot,R,0.,phi=phi,t=t)+Lz2over2R2 > E: return numpy.nan # s.t. this does not get plotted # Find starting value zstart= 1. zmax= 1000. while E-_evaluatePotentials(Pot,R,zstart,phi=phi,t=t)-Lz2over2R2 > 0. \ and zstart < zmax: zstart*= 2. try: out= optimize.brentq(\ lambda z: _evaluatePotentials(Pot,R,z,phi=phi,t=t)+Lz2over2R2-E, 0.,zstart) except ValueError: raise ValueError('No solution for the zero-velocity curve found for this combination of parameters') return out
[docs]@physical_conversion('position',pop=True) def zvc_range(Pot,E,Lz,phi=0.,t=0.): """ NAME: zvc_range PURPOSE: Calculate the minimum and maximum radius for which the zero-velocity curve exists for this energy and angular momentum (R such that Phi(R,0) + Lz/[2R^2] = E) INPUT: Pot - Potential instance or list of such instances E - Energy (can be Quantity) Lz - Angular momentum (can be Quantity) phi - azimuth (optional; can be Quantity) t - time (optional; can be Quantity) OUTPUT: Solutions R such that Phi(R,0) + Lz/[2R^2] = E HISTORY: 2020-08-20 - Written - Bovy (UofT) """ Pot= flatten(Pot) E= conversion.parse_energy(E,**get_physical(Pot)) Lz= conversion.parse_angmom(Lz,**get_physical(Pot)) Lz2over2= Lz**2./2. # Check whether a solution exists RLz= rl(Pot,Lz,t=t,use_physical=False) Rstart= RLz if _evaluatePotentials(Pot,Rstart,0.,phi=phi,t=t)+Lz2over2/Rstart**2. > E: return numpy.array([numpy.nan,numpy.nan]) # Find starting value for Rmin Rstartmin= 1e-8 while _evaluatePotentials(Pot,Rstart,0,phi=phi,t=t)\ +Lz2over2/Rstart**2. < E and Rstart > Rstartmin: Rstart/= 2. Rmin= optimize.brentq(\ lambda R: _evaluatePotentials(Pot,R,0,phi=phi,t=t) +Lz2over2/R**2.-E,Rstart,RLz) # Find starting value for Rmax Rstart= RLz Rstartmax= 1000. while _evaluatePotentials(Pot,Rstart,0,phi=phi,t=t)\ +Lz2over2/Rstart**2. < E and Rstart < Rstartmax: Rstart*= 2. Rmax= optimize.brentq(\ lambda R: _evaluatePotentials(Pot,R,0,phi=phi,t=t) +Lz2over2/R**2.-E,RLz,Rstart) return numpy.array([Rmin,Rmax])
[docs]@physical_conversion('position',pop=True) def rhalf(Pot,t=0.,INF=numpy.inf): """ NAME: rhalf PURPOSE: calculate the half-mass radius, the radius of the spherical shell that contains half the total mass INPUT: Pot - Potential instance or list thereof t= (0.) time (optional; can be Quantity) INF= (numpy.inf) radius at which the total mass is calculated (internal units, just set this to something very large) OUTPUT: half-mass radius HISTORY: 2021-03-18 - Written - Bovy (UofT) """ Pot= flatten(Pot) tot_mass= mass(Pot,INF,t=t) #Find interval rhi= _rhalfFindStart(1.,Pot,tot_mass,t=t) rlo= _rhalfFindStart(1.,Pot,tot_mass,t=t,lower=True) return optimize.brentq(_rhalffunc,rlo,rhi, args=(Pot,tot_mass,t), maxiter=200,disp=False)
def _rhalffunc(rh,pot,tot_mass,t=0.): return mass(pot,rh,t=t)/tot_mass-0.5 def _rhalfFindStart(rh,pot,tot_mass,t=0.,lower=False): """find a starting interval for rhalf""" rtry= 2.*rh while (2.*lower-1.)*_rhalffunc(rtry,pot,tot_mass,t=t) > 0.: if lower: rtry/= 2. else: rtry*= 2. return rtry
[docs]@potential_physical_input @physical_conversion('time',pop=True) def tdyn(Pot,R,t=0.): """ NAME: tdyn PURPOSE: calculate the dynamical time from tdyn^2 = 3pi/[G<rho>] INPUT: Pot - Potential instance or list thereof R - Galactocentric radius (can be Quantity) t= (0.) time (optional; can be Quantity) OUTPUT: Dynamical time HISTORY: 2021-03-18 - Written - Bovy (UofT) """ return 2.*numpy.pi*R*numpy.sqrt(R/mass(Pot,R,use_physical=False))