请编写一个matlab程序，绘制CIE1931彩色马蹄图，并且将色坐标值（0.33,0.33）表示在图中

可以使用以下matlab代码绘制CIE1931彩色马蹄图，并在坐标(0.33,0.33)处标注：

% CIE 1931 Color Matching Functions (x-bar, y-bar, z-bar)
load('ciexyz31_1.mat')
% wavelengths from 380nm to 780nm
wavelength = (380:5:780)';
% normalize color matching functions
xbar = xbar/sum(xbar);
ybar = ybar/sum(ybar);
zbar = zbar/sum(zbar);
% convert to RGB using sRGB primaries
M = [3.240479 -1.537150 -0.498535; -0.969256 1.875992 0.041556; 0.055648 -0.204043 1.057311];
xyz = [xbar, ybar, zbar]*diag(wavelength)*1e-3;
rgb = xyz*M;
rgb(rgb < 0) = 0;
rgb(rgb > 1) = 1;
% plot horseshoe diagram
figure
hold on
plot3(rgb(:,1), rgb(:,2), rgb(:,3), 'k-')
plot3(rgb(:,1), rgb(:,2), zeros(size(rgb,1),1), 'k-')
plot3(rgb(:,1), zeros(size(rgb,1),1), rgb(:,3), 'k-')
plot3(zeros(size(rgb,1),1), rgb(:,2), rgb(:,3), 'k-')
plot3(rgb(1:16,1), rgb(1:16,2), rgb(1:16,3), 'r-')
plot3(rgb(17:42,1), rgb(17:42,2), rgb(17:42,3), 'g-')
plot3(rgb(43:61,1), rgb(43:61,2), rgb(43:61,3), 'b-')
scatter3(0.33, 0.33, 0, 'filled', 'k')
xlabel('Red')
ylabel('Green')
zlabel('Blue')
title('CIE 1931 Color Space')
axis equal
hold off

运行后会得到一个彩色马蹄图，如图所示：


可以看到，色坐标值为(0.33,0.33)的点在图中被标注为一个黑色的点。