变步长lms算法 MATLAB完整代码

以下是变步长LMS算法的MATLAB完整代码：

function [y,e,weights] = variable_step_size_lms(x,d,mu_initial,mu_final,order,initial_weights)
% Inputs:
% x: input signal
% d: desired output signal
% mu_initial: initial step size
% mu_final: final step size
% order: filter order
% initial_weights: initial filter coefficients
%
% Outputs:
% y: filtered output signal
% e: error signal
% weights: final filter coefficients

if nargin < 6
    weights = zeros(order+1,1); % initialize filter coefficients to zeros
else
    weights = initial_weights;
end

y = zeros(size(d)); % initialize filtered output signal to zeros
e = zeros(size(d)); % initialize error signal to zeros

for n = order+1:length(x)
    x_n = x(n:-1:n-order); % current input vector
    y(n) = weights' * x_n; % calculate filtered output
    e(n) = d(n) - y(n); % calculate error signal
    
    % update step size
    mu_n = ((mu_initial-mu_final)/(norm(x_n)^2)) + mu_final;
    
    % update filter coefficients
    weights = weights + mu_n * x_n * e(n);
end

end

其中，`x`和`d`分别表示输入信号和期望输出信号，`mu_initial`和`mu_final`分别表示初始步长和最终步长，`order`表示滤波器阶数，`initial_weights`表示初始权值。函数输出`y`表示滤波器输出信号，`e`表示误差信号，`weights`表示最终的权值。