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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.

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