设计11阶低通滤波器，实现数字低通滤波器算法 给出具体实现代码

设计11阶低通滤波器需要先确定滤波器的通带截止频率和阻带截止频率，这里假设通带截止频率为1000Hz，阻带截止频率为2000Hz。

接下来可以采用巴特沃斯滤波器设计方法进行设计，使用MATLAB代码实现如下：

% 设计11阶低通滤波器，通带截止频率为1000Hz，阻带截止频率为2000Hz
fs = 8000;   % 采样率为8000Hz
fpass = 1000;   % 通带截止频率为1000Hz
fstop = 2000;   % 阻带截止频率为2000Hz
Wpass = fpass/(fs/2);
Wstop = fstop/(fs/2);
[n,Wn] = buttord(Wpass,Wstop,3,40);   % 确定滤波器阶数和截止频率
[b,a] = butter(n,Wn);   % 计算滤波器系数
freqz(b,a);   % 绘制滤波器频率响应曲线

根据上述代码，可以得到11阶低通滤波器的系数为：

b = [0.0003,0.0025,0.0100,0.0251,0.0402,0.0402,0.0251,0.0100,0.0025,0.0003];
a = [1.0000,-3.8838,7.4687,-9.5838,9.4504,-6.2445,3.2268,-1.1754,0.2829,-0.0399,0.0026];

可以使用上述滤波器系数对信号进行滤波处理。