# glider
v'=-sin(th)-d*v^2
th'=(v^2-cos(th))/v
x'=v*cos(th)*scale
y'=v*sin(th)*scale
par d=.25,scale=.1,lg=.04
# these initial data correspond to a nice loop
init th=0.25,v=3
init x=.1,y=.2
# some stuff for the animation 
# glider is just a thick line
# 2*lg=length glider
xl=mod(x,1)-lg*cos(th)
yl=mod(y,1)-lg*sin(th)
xr=mod(x,1)+lg*cos(th)
yr=mod(y,1)+lg*sin(th)
# some controls
@ total=30,dt=.025,bound=1000000
done