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lez 1_ processi stocastici

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Esempio<br />

Random Walk<br />

discrete-time, discrete-state<br />

Xt X t<br />

= 1 t=1,2,3,...<br />

+ t<br />

where t = {1,1} and<br />

p( t<br />

= 1)<br />

= p(<br />

t<br />

= + 1) = 0,5<br />

3<br />

2<br />

1<br />

0<br />

-1<br />

-2<br />

-3<br />

-4<br />

-5<br />

-6<br />

-7<br />

-8<br />

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16<br />

E. Messina Metodi Computazionali<br />

9<br />

Esempio<br />

Changing p>0,5<br />

we obtain a random walk with drift<br />

12<br />

10<br />

p=0,8<br />

8<br />

6<br />

4<br />

2<br />

0<br />

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18<br />

Another way to generalize this process is to let <br />

(discrete time continuous state stochastic process)<br />

t<br />

assume continuous values<br />

t<br />

N(0,1)<br />

5<br />

4<br />

3<br />

2<br />

1<br />

E. Messina<br />

0<br />

-1<br />

-2<br />

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18<br />

Metodi Computazionali<br />

1<br />

0

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