help me plot 3D graph like these picture

Answer 1

[Ameer Hamza]

Try this

x = linspace(0,1,500);
y = linspace(0,1,500);
[Xg, Yg] = meshgrid(x, y);
mask = Yg > sqrt(Xg);
Zg = 1 - Yg;
Zg(~mask) = nan;
surf(Xg, Yg, Zg, 'FaceColor', 'b', 'FaceAlpha', 0.4, 'EdgeColor', 'none')
hold on

y = linspace(0,1,500);
z = linspace(0,1,500);
[Yg, Zg] = meshgrid(y, z);
mask = Yg < 1 - Zg;
Xg = Yg.^2;
Xg(~mask) = nan;
surf(Xg, Yg, Zg, 'FaceColor', 'b', 'FaceAlpha', 0.4, 'EdgeColor', 'none')

view(gca,[115 45]);

[luu minh]

this is what i want to do but i don't understand how to using this method to draw another graph. Can you draw another graph for me to let me know how to using this code to draw another graph

[Ameer Hamza]

The is no direct way to draw such surfaces in MATLAB. If the surfaces are flat, then you can also use patch(). But if they are curved, then we need to deal with every surface individually

% surface x+2y+z=2
x = linspace(0, 1, 500); % range of x-values
y = linspace(0, 1, 500); % range of y-values
[Xg, Yg] = meshgrid(x, y); % mesh of x-y for this surface
mask = Yg < -1/2*Xg + 1; % equation of surface (x+2y+z=2) on the x-y plane is y = -x/2+1
mask = mask & (Yg > 1/2*Xg); % equation of surface (x=2y) on the x-y plane is y = x/2
Zg = 2 - Xg - 2*Yg;
Zg(~mask) = nan;
surf(Xg, Yg, Zg, 'FaceColor', 'b', 'FaceAlpha', 0.4, 'EdgeColor', 'none')
hold on

y = linspace(0, 0.5, 500);
z = linspace(0, 2, 500);
[Yg, Zg] = meshgrid(y, z);
mask = Zg < -4*Yg + 2;
Xg = 2*Yg;
Xg(~mask) = nan;
surf(Xg, Yg, Zg, 'FaceColor', 'b', 'FaceAlpha', 0.4, 'EdgeColor', 'none')

daspect([1 1 1]);
view(gca,[70 30]);

[luu minh]

thank you for your answer