GWFrames

Manipulate gravitational waveforms—changing frames, and so on.

The code in this project extends code written for the paper "Angular velocity of gravitational radiation from precessing binaries and the corotating frame", giving an explicit implementation of the methods discussed in it. The first commit of this project is the last commit of the paper's project.

The license for using this software is basically open (see the LICENSE file in this directory), though citations to the original paper are appreciated, where relevant. Also, if your work depends on features found in this module that have not been described in a separate publication of mine, I would appreciate the opportunity to be a coauthor.

Note that this code is not optimized. In many cases, obvious optimizations were rejected in favor of clearer or simpler code, or code that simply reflected the discussion in the paper more directly. The code is generally more than fast enough for interactive use on individual waveforms, but there is plenty of room for improvement. In particular, rotations may be painfully slow for large data sets.

Build requirements

To build just the C++ code:

• C++ compiler
• GNU Scientific Library, built as a shared library

To use the optional—but highly recommended—Python interface:

• SWIG v3.0 or greater
• HDF5 v1.8.10 or greater, built as a shared library with development headers (libhdf5-dev or similar)
• FFTW v3.2 or greater, built as a shared library

And, of course, python and a few of its goodies, for which I cannot recommend anaconda highly enough -- it makes installation and maintenance of the python software stack vastly easier.

• Python v2.7.4 or greater (untested on python3+), with development headers (python-dev or similar)
• NumPy v1.7 or greater (conda install numpy)
• Matplotlib v1.2 or greater (conda install matplotlib)
• h5py v2.1 or greater (conda install h5py)
• IPython v2.0 or greater, with notebook (conda install ipython)

All of the above are reasonably standard, and can be installed easily through package managers such as apt and homebrew. The notebook interface for IPython provides an environment much like the Mathematica notebook interface. The examples are provided in a notebook (.ipynb) file.

Getting started

The first step is to clone the git repo and its submodules:

git clone https://github.com/moble/GWFrames.git
cd GWFrames
git submodule init
git submodule update

The code is mostly in the form of C++, for speed. All functions are provided in the GWFrames namespace. The interface is reasonably straightforward, and can easily be included into and compiled with other code. Look for examples of how to do this in the C++Example directory. (See below for a few more details.)

However, it is mostly intended to be used through the interface to python. With the above-listed requirements, build the code and install to the user directory. To do this, run make or

python setup.py install --user

After this, you should be able to start a new python session (in any directory) and import GWFrames, which is the basic module provided by this code. The primary objects are Quaternion and Waveform objects, with various methods defined for each. An IPython notebook in the Docs directory contains extensive examples, following the outline of the paper. To use it, run

ipython notebook Docs/AngVelOfGravRadFromPrecessingBinaries_CorotatingFrame.ipynb --pylab

Alternatively, this code may be used directly through its C++ interface. A simple example is provided in the C++Example directory, along with the Makefiles needed to build all the necessary code. If it does not compile easily, make sure the various paths in both Makefiles are set properly.

Detailed documentation of most functions may be found through python's help function, or by running make in the Docs subdirectory, and reading Docs/html/index.html.

Contributions

The code is primarily written by me (Mike Boyle). Dan Hemberger helped by porting some of my older code from Triton to perform noise-weighted overlap calculations, and with numerous bug reports and helpful suggestions. Serguei Ossokine also helped substantially by cross-checking the post-Newtonian formulas and results.

Other contributions are entirely welcome. The preferred method is via github's excellent interface. If you have a bug report, just go to the issues page for this repo, check for related issues, and if this is new click "New Issue". If you want to contribute code, it is easiest for everyone if you use the [fork & pull method described here] (https://help.github.com/articles/using-pull-requests).