ssbm.m

哈夫曼树

function ssbm(str)
if ~exist('str','var')
    str='aedbaccde'; % the string to be coded
end
p=[0.2 0.3 0.1 0.15 0.25] %predetermined probability
l=0;d=1;%d is the range of probability
n=length(str);
disp('编码由a b c d e组成');
n=length(str);
for i=1:n
    m=str(i)-'a'+1;%subtraction of ASCII
    if m<1|m>5 error('请不要输入其他字符'); end
    pl=0;pr=0;
    for j=1:m-1
        pl=pl+p(j);
    end
    for j=1:m
        pr=pr+p(j);
    end
    l=l+d*pl; %l-left, r-right
    r=l+d*(pr-pl);
    disp(['第 ',num2str(i),' 个字符的左边界']);
    format long;
    disp(l);
    disp(['第 ',num2str(i),' 个字符的右边界']);
    disp(r);
    d=r-l;
end