The RV Model

class radvel.model.GeneralRVModel(params, forward_model, time_base=0)

A generalized Model

Parameters:

• params (radvel.Parameters) – The parameters upon which the RV model depends.
• forward_model (callable) –

  The function that defines the signal as a function of time and parameters. The forward model is called as

  forward_model(time, params, *args, **kwargs) -> float

• time_base (float) – time relative to which ‘dvdt’ and ‘curv’ terms are computed.

Examples

>>> import radvel
#  In this example, we'll assume a function called 'my_rv_function' that
#  computes RV values has been defined elsewhere. We'll assume that
#  'my_rv_function' depends on planets' usual RV parameters
#  contained in radvel.Parameters as well as some additional
#  parameter, 'my_param'.
>>> params = radvel.Parameters(2)
>>> params['my_param'] = rv.Parameter(my_param_value,vary=True)
>>> rvmodel = radvel.GeneralRVModel(myparams,my_rv_function)
>>> rv = rvmodel(10)

__call__(t, *args, **kwargs)

Compute the signal

Parameters:t (array of floats) – Timestamps to calculate the model Returns:model at each time in t Return type:vel (array of floats)

__init__(params, forward_model, time_base=0)

Initialize self. See help(type(self)) for accurate signature.

__weakref__

list of weak references to the object (if defined)

class radvel.model.Parameter(value=None, vary=True, mcmcscale=None, linear=False)

Object to store attributes of each orbital parameter .. attribute:: value

value of parameter.

type:float

vary

True if parameter is allowed to vary in MCMC or max likelihood fits, false if fixed

Type:Bool

mcmcscale

step size to be used for MCMC fitting

Type:float

linear

if vary=False and linear=True for gamma parameters then they will be calculated analytically using the trick. derived by Timothy Brandt.

Type:bool

__init__(value=None, vary=True, mcmcscale=None, linear=False)

Initialize self. See help(type(self)) for accurate signature.

__repr__()

Return repr(self).

__weakref__

list of weak references to the object (if defined)

class radvel.model.Parameters(num_planets, basis='per tc secosw sesinw logk', planet_letters=None)

Object to store the model parameters.

Parameters to describe a radial velocity orbit stored as an OrderedDict.

Parameters:

• num_planets (int) – Number of planets in model
• basis (string) – parameterization of orbital parameters. See radvel.basis.Basis for a list of valid basis strings.
• planet_letters (dict [optional) – custom map to match the planet numbers in the Parameter object to planet letters. Default {1: ‘b’, 2: ‘c’, etc.}. The keys of this dictionary must all be integers.

basis

Basis object

Type:radvel.Basis

planet_parameters

orbital parameters contained within the specified basis

Type:list

num_planets

number of planets in the model

Type:int

Examples

>>> import radvel
# create a Parameters object for a 2-planet system with
# custom planet number to letter mapping
>>> params = radvel.Parameters(2, planet_letters={1:'d', 2:'e'})

__init__(num_planets, basis='per tc secosw sesinw logk', planet_letters=None)

Initialize self. See help(type(self)) for accurate signature.

__reduce__()

Return state information for pickling

tex_labels(param_list=None)

Map Parameters keys to pretty TeX code representations.

Parameters:param_list (list [optional]) – Manually pass a list of parameter labels Returns:dictionary mapping Parameters keys to TeX code Return type:dict

class radvel.model.RVModel(params, time_base=0)

Generic RV Model

This class defines the methods common to all RV modeling classes. The different RV models, with different parameterizations, all inherit from this class.

__init__(params, time_base=0)

Initialize self. See help(type(self)) for accurate signature.