Arithmetic Coding in matlab

Hi! I have to do arithmetic coding in matlab. Please help me

There are four symbols A, B, C, and D, whose probability of occurrence is 0.1, 0.2, 0.3,
and 0.4 respectively.
a) Calculate the entropy..
b) Find the arithmetic code of message ACAD in binary number.
c) From the result b), find the number of bits per symbol and the code efficiency.

[José-Luis]

Any particular reason someone should do your homework? What have you tried so far? What particular problems have you encountered in your implementation?

http://en.wikipedia.org/wiki/Arithmetic_coding

[Qura]

At that time I was severely ill and try to understand but cant, but I did all by myself