请提供matlab进行Harris角点检测的代码

以下是matlab进行Harris角点检测的代码：

% 读取图像
img = imread('image.jpg');

% 转换为灰度图像
gray_img = rgb2gray(img);

% 计算梯度
[Ix, Iy] = gradient(double(gray_img));

% 计算矩阵M
Ix2 = Ix.^2;
Iy2 = Iy.^2;
Ixy = Ix.*Iy;

% 设置窗口大小
window_size = 3;

% 计算每个像素的响应函数R
k = 0.04;
R = zeros(size(gray_img));
for i = 1:size(gray_img, 1)
for j = 1:size(gray_img, 2)
% 计算M的和
M = [sum(sum(Ix2(i:i+window_size-1, j:j+window_size-1))) sum(sum(Ixy(i:i+window_size-1, j:j+window_size-1))); ...
sum(sum(Ixy(i:i+window_size-1, j:j+window_size-1))) sum(sum(Iy2(i:i+window_size-1, j:j+window_size-1)))];
% 计算R
R(i, j) = det(M) - k*(trace(M))^2;
end
end

% 设置阈值
threshold = 100000;

% 找到角点
corners = (R > threshold);

% 显示结果
imshow(img);
hold on;
[x, y] = find(corners);
plot(y, x, 'r.');