This added the script "CH4_circular" that was used to calculate the response trajectories produced in Figure 7.  Matt, you probably won't like this, but it's simply an inefficient script.  Uncomment/comment the different lines of code to specify prey located at different regions around the predator. It requires the Matlab circular statistics toolbox, which can be downloaded at
http://www.mathworks.com/matlabcentral/fileexchange/10676

Also included is the function "whose," which is just a simple function for producing logicals of prey based on approach speed. Approach speed (2, 11, or 20) is the only input for whose.m