# a simple thermal ratchet
wiener w
par a=.8,sig=.05,alpha=.1,beta=.1
# piecewise linear potential with slope
# 1 from 0 to a and slope -a/(1-a) from a to 1
#  f = -V'
f(x)=if(x<a)then(-1)else(a/(1-a))
x'=z*f(mod(x,1))+sig*w
# z is two states
markov z 2
{0} {alpha}
{beta} {0}
@ meth=euler,dt=.1,total=2000,njmp=10
@ xhi=2000,yhi=8,ylo=-8
done