function?[entropy]=Entropy（seq）
%the?function?that?calculate?the?source?entropy
alpha（1）=seq（1）;
prob（1）=1;
l=length（seq）;
k=2;
%statistic?the?symbol?that?in?the?source?file?and??the?numbers.
for?i=2:l
????%check?whether?there?is?the?current?symbol?in?the?alpha?array
????idx=find（alpha==seq（i））;
????if?isempty（idx）%if?notadd?it
????????alpha（k）=seq（i）;
????????prob（k）=1;
????????k=k+1;
????else
????????prob（idx）=prob（idx）+1;?%if?there?is?add?1
????end
end
%caculate?the?probability
prob=prob./l;
%caculate?the?entropy
entropy=-prob.*log2（prob）;
entropy=sum（entropy（:））;
end

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????4989??2009-12-11?10:21??LZ\decode.txt

?????文件??????17721??2009-12-11?10:21??LZ\encode.txt

?????文件????????602??2009-09-28?13:18??LZ\Entropy.m

?????文件????????826??2009-09-28?13:05??LZ\LZcode.m

?????文件????????251??2009-09-28?13:13??LZ\LZdecode.m

?????文件????????245??2009-09-28?13:12??LZ\LZencode.m

?????文件???????1370??2009-09-28?13:24??LZ\LZmain.m

?????文件???????4991??2009-09-24?00:18??LZ\source.txt

?????目錄??????????0??2009-12-11?10:19??LZ

-----------?---------??----------?-----??----

????????????????30995????????????????????9