Risultati per

• Plotting the Potential Energy and Identifying Extrema

% Define the range of x values

x = linspace(-2, 2, 1000);

% Define the potential function V(x)

V = -x.^2 / 2 + x.^4 / 4;

% Plot the potential function

figure;

plot(x, V, 'LineWidth', 2);

hold on;

% Mark the minima at x = ±1

plot([-1, 1], [-1/4, -1/4], 'ro', 'MarkerSize', 5, 'MarkerFaceColor', 'g');

% Add LaTeX title and labels

title('Duffing Potential Energy: $$V(x) = -\frac{x^2}{2} + \frac{x^4}{4}$$', 'Interpreter', 'latex');

xlabel('$$x$$', 'Interpreter', 'latex');

ylabel('$$V(x)$$','Interpreter', 'latex');

grid on;

hold off;

• Solving and Plotting the Duffing Equation

% Define the system of ODEs for the non-chaotic Duffing equation

duffing_ode = @(t, X) [X(2);

X(1) - X(1).^3];

% Time span for the simulation

tspan = [0 10];

% Initial conditions [x(0), v(0)]

initial_conditions = [1; 1];

% Solve the ODE using ode45

[t, X] = ode45(duffing_ode, tspan, initial_conditions);

% Extract displacement (x) and velocity (v)

x = X(:, 1);

v = X(:, 2);

% Plot both x(t) and v(t) in the same figure

figure;

plot(t, x, 'b-', 'LineWidth', 2); % Plot x(t) with blue line

hold on;

plot(t, v, 'r--', 'LineWidth', 2); % Plot v(t) with red dashed line

% Add title, labels, and legend

title(' Component curve solutions to $$\ddot{x}-x+x^3=0$$','Interpreter', 'latex');

xlabel('t','Interpreter', 'latex');

ylabel('$$x(t) $$ and $$v(t) $$','Interpreter', 'latex');

legend('$$x(t)$$', ' $$v(t)$$','Interpreter', 'latex');

grid on;

hold off;

% Phase portrait with nullclines, equilibria, and vector field

figure;

hold on;

% Plot phase portrait

plot(x, v,'r', 'LineWidth', 2);

% Plot equilibrium points

plot([0 1 -1], [0 0 0], 'ro', 'MarkerSize', 5, 'MarkerFaceColor', 'g');

% Create a grid of points for the vector field

[x_vals, v_vals] = meshgrid(linspace(-2, 2, 20), linspace(-1, 1, 20));

% Compute the vector field components

dxdt = v_vals;

dvdt = x_vals - x_vals.^3;

% Plot the vector field

quiver(x_vals, v_vals, dxdt, dvdt, 'b');

% Set axis limits to [-1, 1]

xlim([-1.7 1.7]);

ylim([-1 1]);

% Labels and title

title('Phase-Plane solutions to $$\ddot{x}-x+x^3=0$$','Interpreter', 'latex');

xlabel('$$ (x)$$','Interpreter', 'latex');

ylabel('$$v(v)$$','Interpreter', 'latex');

grid on;

hold off;

% Lorenz Attractor Parameters

sigma = 10;

beta = 8/3;

rho = 28;

% Lorenz system of differential equations

f = @(t, a) [-sigma*a(1) + sigma*a(2);

rho*a(1) - a(2) - a(1)*a(3);

-beta*a(3) + a(1)*a(2)];

% Time span

tspan = [0 100];

% Initial conditions

a0 = [1 1 1];

% Solve the system using ode45

[t, a] = ode45(f, tspan, a0);

% Plot using scatter3 with time-based color mapping

figure;

scatter3(a(:,1), a(:,2), a(:,3), 5, t, 'filled'); % 5 is the marker size

title('Lorenz Attractor');

xlabel('x(t)');

ylabel('y(t)');

zlabel('z(t)');

grid on;

colorbar; % Add a colorbar to indicate the time mapping

view(3); % Set the view to 3D

% Define the parameters

a = 2.07;

b = 1.79;

% Define the system of differential equations

dynamics = @(t, X) [ ...

X(2) + a * X(1) * X(2) + X(1) * X(3); % dx/dt

1 - b * X(1)^2 + X(2) * X(3); % dy/dt

X(1) - X(1)^2 - X(2)^2 % dz/dt

];

% Initial conditions

X0 = [0.63; 0.47; -0.54];

% Time span

tspan = [0 100];

% Solve the system using ode45

[t, X] = ode45(dynamics, tspan, X0);

% Plot the results with color gradient

figure;

colormap(jet); % Set the colormap

c = linspace(1, 10, length(t)); % Color data based on time

% Create a 3D line plot with color based on time

for i = 1:length(t)-1

plot3(X(i:i+1,1), X(i:i+1,2), X(i:i+1,3), 'Color', [0 0.5 0.9]*c(i)/10, 'LineWidth', 1.5);

hold on;

end

% Set plot properties

title('Sprott Attractor');

xlabel('x(t)');

ylabel('y(t)');

zlabel('z(t)');

grid on;

colorbar; % Add a colorbar to indicate the time mapping

view(3); % Set the view to 3D

hold off;

% Define the parameters

a = 0.2;

b = 0.2;

c = 5.7;

% Define the system of differential equations

dynamics = @(t, X) [ ...

-(X(2) + X(3)); % dx/dt

X(1) + a * X(2); % dy/dt

b + X(3) * (X(1) - c) % dz/dt

];

% Initial conditions

X0 = [10.0; 0.00; 10.0];

% Time span

tspan = [0 100];

% Solve the system using ode45

[t, X] = ode45(dynamics, tspan, X0);

% Plot the results

figure;

scatter3(X(:,1), X(:,2), X(:,3), 5, t, 'filled');

title('Rössler Attractor');

xlabel('x(t)');

ylabel('y(t)');

zlabel('z(t)');

grid on;

colorbar; % Add a colorbar to indicate the time mapping

view(3); % Set the view to 3D

%% Parameters for Rabinovich-Fabrikant Attractor

alpha = 0.14;

gamma = 0.10;

dt = 0.01;

num_steps = 5000;

% Initial conditions

x0 = -1;

y0 = 0;

z0 = 0.5;

% Preallocate arrays for performance

x = zeros(1, num_steps);

y = zeros(1, num_steps);

z = zeros(1, num_steps);

% Set initial values

x(1) = x0;

y(1) = y0;

z(1) = z0;

% Generate the attractor

for i = 1:num_steps-1

x(i+1) = x(i) + dt * (y(i)*(z(i) - 1 + x(i)^2) + gamma*x(i));

y(i+1) = y(i) + dt * (x(i)*(3*z(i) + 1 - x(i)^2) + gamma*y(i));

z(i+1) = z(i) + dt * (-2*z(i)*(alpha + x(i)*y(i)));

end

% Create a time vector for color mapping

t = linspace(0, 100, num_steps);

% Plot using scatter3

figure;

scatter3(x, y, z, 5, t, 'filled'); % 5 is the marker size

title('Rabinovich-Fabrikant Attractor');

xlabel('x(t)');

ylabel('y(t)');

zlabel('z(t)');

grid on;

colorbar; % Add a colorbar to indicate the time mapping

view(3); % Set the view to 3D

1. Strange Attractors
2. Attractor

1. Create and save a "template file" with the desired label and then call copyfile to make a copy of that file and then write your results to the new copy, or
2. If using Windows you can create and/or open the file using ActiveX and then apply the desired label from your MATLAB program's code.

Interesting Questions

Popular Discussions

From the Blogs

Gabriel’s horn is formed by taking the graph of with the domain and rotating it in three dimensions about the axis.

There is a standard formula for calculating the volume of this shape, for a general function .Wwe will just state that the volume of the solid between a and b is:

This is an improper integral and it's hard to evaluate, but since in our interval

% Define the function for Gabriel's Horn

gabriels_horn = @(x) 1 ./ x;

% Create a range of x values

x = linspace(1, 40, 4000); % Increase the number of points for better accuracy

y = gabriels_horn(x);

% Create the meshgrid

theta = linspace(0, 2 * pi, 6000); % Increase theta points for a smoother surface

[X, T] = meshgrid(x, theta);

Y = gabriels_horn(X) .* cos(T);

Z = gabriels_horn(X) .* sin(T);

% Plot the surface of Gabriel's Horn

figure('Position', [200, 100, 1200, 900]);

surf(X, Y, Z, 'EdgeColor', 'none', 'FaceAlpha', 0.9);

hold on;

% Plot the central axis

plot3(x, zeros(size(x)), zeros(size(x)), 'r', 'LineWidth', 2);

% Set labels

xlabel('x');

ylabel('y');

zlabel('z');

% Adjust colormap and axis properties

colormap('gray');

shading interp; % Smooth shading

% Adjust the view

view(3);

axis tight;

grid on;

% Add formulas as text annotations

dim1 = [0.4 0.7 0.3 0.2];

annotation('textbox',dim1,'String',{'$$V = \pi \int_{1}^{a} \left( \frac{1}{x} \right)^2 dx = \pi \left( 1 - \frac{1}{a} \right)$$', ...

'', ... % Add an empty line for larger gap

'$$\lim_{a \to \infty} V = \lim_{a \to \infty} \pi \left( 1 - \frac{1}{a} \right) = \pi$$'}, ...

'Interpreter','latex','FontSize',12, 'EdgeColor','none', 'FitBoxToText', 'on');

dim2 = [0.4 0.5 0.3 0.2];

annotation('textbox',dim2,'String',{'$$A = 2\pi \int_{1}^{a} \frac{1}{x} \sqrt{1 + \left( -\frac{1}{x^2} \right)^2} dx > 2\pi \int_{1}^{a} \frac{dx}{x} = 2\pi \ln(a)$$', ...

'', ... % Add an empty line for larger gap

'$$\lim_{a \to \infty} A \geq \lim_{a \to \infty} 2\pi \ln(a) = \infty$$'}, ...

'Interpreter','latex','FontSize',12, 'EdgeColor','none', 'FitBoxToText', 'on');

% Add Gabriel's Horn label

dim3 = [0.3 0.9 0.3 0.1];

annotation('textbox',dim3,'String','Gabriel''s Horn', ...

'Interpreter','latex','FontSize',14, 'EdgeColor','none', 'HorizontalAlignment', 'center');

hold off

daspect([3.5 1 1]) % daspect([x y z])

view(-27, 15)

lightangle(-50,0)

lighting('gouraud')

1. How to Find the Volume and Surface Area of Gabriel's Horn
2. Gabriel's Horn
3. An Understanding of a Solid with Finite Volume and Infinite Surface Area.
4. IMPROPER INTEGRALS: GABRIEL’S HORN
5. Gabriel’s Horn and the Painter's Paradox in Perspective

clear

close all

gm = importGeometry( "ForearmLink.stl" );

pdegplot(gm)

1. Note that I cant seem to rotate continuously around the x-axis. It appears to only support rotations from [0, 360] as opposed to [-inf, inf]. So, for example, if I'm looking in the Y+ direction and rotate around X so that I'm looking at the Z- direction, and then want to look in the Y- direction, I can't simply keep rotating around the X axis... instead have to rotate 180 degrees around the Z axis and then around the X axis. I'm not aware of any data visualization applications (e.g., ParaView, VisIt, EnSight) or CAD/CAE tools with such an interaction.
2. Note that at the 50 second mark, I set a view in ParaView: looking in the [X-, Y-, Z-] direction with Y+ up. Try as I might in Matlab, I'm unable to achieve that same view perspective.