fds is a research tool for computational simulations that exhibis chaotic dynamics. It computes sensitivity derivatives of time averaged quantities, a.k.a. statistics, with respect simulation parameters.
For an introduction of chaotic dynamics, I highly recommend Strogatz's excellent book. For a statistical view of chaotic dynamical systems, please refer to Berlinger's article. Algorithm used in this software is described in the upcoming AIAA paper
The best way to download fds is using pip. Pip is likely included in your Python installation. If not, see instruction here. To install fds using pip, simply type
sudo pip install fds