read AppsWZmulti:

#symmetirc random walk in the square lattice
L:=[[[1,0],1/4],[[-1,0],1/4],[[0,1],1/4],[[0,-1],1/4] ]:





print(`Consider a walk in the square lattice where the `):
print(`distribution of the fundamental steps is`):
print(L):

print(`Let a(n) be the probability of being at the origin after n steps.`):
print(`the probability of returning to the origin after n steps .`):


print(`The linear recurrence operator annihilating a_n:=`):
print(RandomWalkRecurrence(L,n,N));
print(`The whole thing took`, time(), `seconds of CPU time `):

quit: