function [] = return_probability_plot(x, y, data, sinth, costh)

% retplot(x, y, data, sinth, costh) -- plot a return probability "blip"

data = data .^ 2;  % oops!  I was a bozo... =)
xx = x + [data data].*[costh -costh];
yy = y + [data data].*[sinth -sinth];
plot([xx xx(1)],[yy yy(1)]);
