irr2u(n,length,driftx,drifty) simulates an two-dimensional
asymmetric random walk and plots it.
n is the number of steps, length is the maximum step size.
driftx and drifty can cause a drift of the particle to the right or the top respectively.
irr2s(n,length) uses driftx = drifty = 0.
irr2s uses n = 1000, length = 10 in addition.
This file was generated by students as a partial fulfillment
for the requirements of the course "Fractals",
2004/2005, Stuttgart University.