Arithmetic Coding Example

• P(a) = 1/3, P(b) = 2/3

• C(a) = 0, C(b) = 1/3

• abba

symbol l r w output

0 1 1

a 0 1/3 1/3

0 2/3 2/3 0

b 2/9 6/9 4/9

b 10/27 18/27 8/27

a 30/81 46/81 16/81

.0101... .1001... 1

w := r - l;

l := l + w C(x);
r := l + w P(x)

Note: Code for abb is the same as that for abba. The decoder

knows the length to be able to distinguish.

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