function s = ami_decode(a)n = length(a);s = zeros(1,n);sg = 1;for i = 1:n if a(i) == 0 s(i) = 0; elseif a(i) == 1 if mod(sg,2) == 0 s(i) = 0; else s(i) = 1; sg = sg + 1; end elseif a(i) == -1 if mod(sg,2) == 0 s(i) = 0; else s(i) = -1; sg = sg + 1; end end s(i) = s(i-1);endend MATLAB运行显示下标索引必须为正整数类型或逻辑类型。 出错 s(i)=s(i-1); 如何修改代码

可以将循环的第一次迭代单独处理，避免在第一次迭代时访问s的负数索引。可以在循环之前将s的第一个元素初始化为0，或者在第一次迭代时将s(i-1)替换为0。以下是修改后的代码：

function s = ami_decode(a)
n = length(a);
s = zeros(1,n);
sg = 1;
for i = 1:n
    if a(i) == 0
        s(i) = 0;
    elseif a(i) == 1
        if mod(sg,2) == 0
            s(i) = 0;
        else
            s(i) = 1;
            sg = sg + 1;
        end
    elseif a(i) == -1
        if mod(sg,2) == 0
            s(i) = 0;
        else
            s(i) = -1;
            sg = sg + 1;
        end
    end
    if i > 1
        s(i) = s(i-1);
    end
end
end