输入以下是AMI码的解码代码和波形绘制代码： 解码代码： 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 end end 波形绘制代码： n = 20; y = zeros(1,n); x1 = [ones(1,n/2) zeros(1,n/2)]; x0 = zeros(1,n); x2 = [-ones(1,n/2) zeros(1,n/2)]; z = zeros(size(1,nsn)); for i = 1:sn switch a(i) case 1 y = x1; case -1 y = x2; case 0 y = x0; end z(1,[(i-1)n+1:in]) = y; end ii = (1:nsn)/n; plot(ii,z); grid on;时，MATLAB中只显示AMI编码的波形 AMI解码波形为空，应如何修改

根据提供的代码，AMI解码波形为空可能是因为解码代码中的s向量没有被正确赋值。可以尝试在解码代码中加入以下语句，以确保解码后的s向量被正确赋值：

s(i) = s(i-1);

修改后的解码代码如下：

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);
end
end

加入这个语句后，解码后的s向量就能正确赋值，AMI解码波形也能正确显示。