说明：问题来自CSDN-问答板块，题主提问。

需求：如何用子图命令画出平面y=2z，z=2y与球面x^2+y^2+z^2=5相交的空间曲线图形。需要完整代码和结果的图片。 

 

一、先看效果图

 

二、代码

% 创建figure
figure

% 创建二维网格，用于定义平面
[y_plane, z_plane] = meshgrid(linspace(-sqrt(5), sqrt(5), 100));

% 对应的x_plane都为0
x_plane = zeros(size(y_plane));

% 绘制平面 y = 2z
surf(x_plane, y_plane, z_plane, 'FaceAlpha', 0.5)
hold on

% 创建二维网格，用于定义平面
[y_plane2, x_plane2] = meshgrid(linspace(-sqrt(5), sqrt(5), 100));

% 对应的z_plane2为2*y_plane2
z_plane2 = 2*y_plane2;

% 绘制平面 z = 2y
surf(x_plane2, y_plane2, z_plane2, 'FaceAlpha', 0.5, 'FaceColor', 'y')

% 创建球面
[phi, theta] = meshgrid(linspace(0, 2*pi, 40), linspace(0, pi, 40));
x_sphere = sqrt(5)*sin(phi).*cos(theta);
y_sphere = sqrt(5)*sin(phi).*sin(theta);
z_sphere = sqrt(5)*cos(phi);
surf(x_sphere, y_sphere, z_sphere, 'FaceAlpha', 0.5, 'FaceColor', 'green');

% 做交线的处理
% 通过参数t来表示交线，取值范围为[-sqrt(5), sqrt(5)]
t = linspace(-sqrt(5), sqrt(5), 100);
x_line = zeros(1, numel(t));
y_line = t / 2;
z_line = 2 * t;
% 绘制交线
plot3(x_line, y_line, z_line, 'k', 'LineWidth', 2)

xlabel('x')
ylabel('y')
zlabel('z')

legend('y = 2z', 'z = 2y', 'Sphere', 'Intersection line')
view(3)