Plot 3D Contour plot on Surface Plot

I am trying to plot a contour 3D ontop of a surface plot. But, I do not understand why no contours are being plotted. Code being...mains cript first followed by an associated function.

%% Main Script.
%% Clear the MATLAB Workspace.
clear
clc
close all
format compact
format long
% Constants.
mu = 0.0121505856;   % Mass parameter.
% Setup the mesh for computing the effective potential some range and
% in steps of n.
X         = -2:0.01:2;
Y         = X;
[ x, y ]  = meshgrid(X, Y);
% Compute the effective potential.
U_bar = Effective_Potential(x, y, mu);
% Plot the contours of the effective potential.
figure(1),
surf(x, y, U_bar, 'EdgeColor', 'none'), ax = gca; 
ax.CLim = [1.5 5.0]; grid on, hold on,
contour3(U_bar, 10, '-k', 'Linewidth', 1.5), hold off,
title('Earth-Moon Pseudo Potential', 'Fontsize', 15),
xlabel('x'), ylabel('y'), zlabel('z'),
axis([-1.5 1.5 -1.5 1.5 1.49 5.0]), view([26, 40]), 
colorbar, colormap('turbo'), shading('interp')

%% Asscoiated functions.
function [ U ] = Effective_Potential(x, y, mu)
% Inputs:
%  x:   A 2D mesh grid of N by N size for the x-coordinate.
%  y:   A 2D mesh grid of N by N size for the y-coordinate.
%  mu:  The mass parameter for a CR3BP system.
% Outputs:
%  U_bar:   2D mesh grid of N by N size containing the effective 
%  potential values for the given x and y coordinates.

% Compute the distance of the s/c from the smaller primary.
r_1 = sqrt((x + mu - 1).^2 + y.^2);

% Compute the distance of the s/c from the bigger primary.
r_2 = sqrt((x + mu).^2 + y.^2);

% Compute the effective potential. 
U = -(-(1 - mu)./r_2 - mu./r_1 -(1/2)*(x.^2 + y.^2));
end

Answer 1

[Voss]

Here I specify x and y as well as the contour levels in the contour3 call. Adjust as desired.

%% Main Script.
%% Clear the MATLAB Workspace.
clear
clc
close all
format compact
format long
% Constants.
mu = 0.0121505856;   % Mass parameter.
% Setup the mesh for computing the effective potential some range and
% in steps of n.
X         = -2:0.01:2;
Y         = X;
[ x, y ]  = meshgrid(X, Y);
% Compute the effective potential.
U_bar = Effective_Potential(x, y, mu);
% Plot the contours of the effective potential.
figure(1),
surf(x, y, U_bar, 'EdgeColor', 'none'), ax = gca; 
ax.CLim = [1.5 5.0]; grid on, hold on,
contour3(x, y, U_bar, 1.5:0.1:5.0, '-k', 'Linewidth', 1.5), hold off,
title('Earth-Moon Pseudo Potential', 'Fontsize', 15),
xlabel('x'), ylabel('y'), zlabel('z'),
axis([-1.5 1.5 -1.5 1.5 1.49 5.0]), view([26, 40]), 
colorbar, colormap('turbo'), shading('interp')

%% Asscoiated functions.
function [ U ] = Effective_Potential(x, y, mu)
% Inputs:
%  x:   A 2D mesh grid of N by N size for the x-coordinate.
%  y:   A 2D mesh grid of N by N size for the y-coordinate.
%  mu:  The mass parameter for a CR3BP system.
% Outputs:
%  U_bar:   2D mesh grid of N by N size containing the effective 
%  potential values for the given x and y coordinates.

% Compute the distance of the s/c from the smaller primary.
r_1 = sqrt((x + mu - 1).^2 + y.^2);

% Compute the distance of the s/c from the bigger primary.
r_2 = sqrt((x + mu).^2 + y.^2);

% Compute the effective potential. 
U = -(-(1 - mu)./r_2 - mu./r_1 -(1/2)*(x.^2 + y.^2));
end

[Dyuman Joshi]

In short - Use the proper syntax for contourf and specify the contour values within the modified color limits.

[Mark]

Gotcha! Thanks so much. It works.

[Voss]

You're welcome!