# the clock model - a linearly decaying spiral that is kicked out
# by a fixed amount
x'=-a*x-b*y
y'=-a*y+b*x
global -1 y {x=x-k}
par a=.1,b=1,k=.5
init x=1,y=0
@ total=100,xlo=-1.5,ylo=-1,xhi=1.5,yhi=1,xp=x,yp=y
done