# logliap.ode
# the liapunov exponent of the logistic map
f(x)=a*x*(1-x)
fp(x)=a*(1-2*x)
init x=.1,a=2,z=0
x'=f(x)
a'=a
z'=z+heav(t-100)*ln(abs(fp(x))+1e-8)
aux liap=z/max(t-100,1)
@ xlo=2,xhi=4,ylo=-2,yhi=1
@ total=2000,trans=2000
@ meth=disc,bound=1000000
@ xp=a,yp=liap
done