Installation

Install from pypi:

pip install ttvfast

or download and compile the code with

python setup.py build_ext --inplace

For the latest development version, install with pip:

pip install git+https://github.com/mindriot101/ttvfast.git

or clone from git:

git clone https://github.com/mindriot101/ttvfast-python.git
cd ttvfast-python
git submodule init
git submodule update # grabs code from TTVFast

then test that everything built properly using:

$ py.test
============================== test session starts ===============================
testing/test_lweiss.py .
testing/test_models.py ...
testing/test_python_api.py ...
testing/test_ttvfast.py ...

Usage

To compute the TTV properties for one or more planets:

• build a ttvfast.models.Planet instance (see the class documentation for required parameters)

• pass a list of the planets in the system to ttvfast.ttvfast along with:

  • the stellar mass in units of solar mass,

  • the start point of the integration in days,

  • the time step for the integration in days,

  • and the end point for integration in days.

The function ttvfast.ttvfast returns a dictionary containing positions and rv. The positions entry is a tuple of:

1. a list of integer indices for which values correspond to which planet,

2. a list of integers defining the epoch,

3. a list of times,

4. a list of rsky values, and

5. a list of vsky values.

The optional rv_times parameter takes a list of RV times on which the RV is to be calculated. If so the rv entry in the output dictionary is populated with a list of RV values, and otherwise None.

For more details, see the original C module’s documentation: https://github.com/kdeck/TTVFast/blob/master/c_version/README

Citations

If you use this code, please cite Deck, Agol, Holman, & Nesvorny (2014), ApJ, 787, 132, arXiv:1403.1895.

-Katherine Deck, Eric Agol, Matt Holman, & David Nesvorny