gravity simulation in matlab

To simulate the behavior of objects under the influence of gravity, we can use numerical methods to solve the equations of motion. Here's an example implementation of a gravity simulation in MATLAB using the Verlet integration algorithm:

main.m
% Parameters
num_bodies = 3;
G = 6.6743e-11; % gravitational constant
dt = 0.01; % time step

% Initial conditions
r0 = [1, 0, 0; -1/2, sqrt(3)/2, 0; -1/2, -sqrt(3)/2, 0]; % initial positions
v0 = [0, 0, 0; 0, 0, 0; 0, 0, 0]; % initial velocities
m = [5.972e24; 7.342e22; 1]; % masses

% Simulation loop
r = r0; v = v0; % set initial conditions
for i = 1:1000 % run for 1000 time steps
    % Compute acceleration using current positions
    a = zeros(num_bodies, 3);
    for j = 1:num_bodies
        for k = 1:num_bodies
            if j ~= k
                rjk = r(j,:) - r(k,:);
                a(j,:) = a(j,:) - G*m(k)*rjk/norm(rjk)^3;
            end
        end
    end
    
    % Update positions using Verlet algorithm
    r_new = 2*r - r0 + a*dt^2;
    
    % Update velocities using central difference method
    v_new = (r_new - r0)/(2*dt);
    
    % Update variables for next iteration
    r0 = r; r = r_new;
    v0 = v; v = v_new;
    
    % Plot current positions
    plot3(r(:,1), r(:,2), r(:,3), 'o');
    axis([-2, 2, -2, 2, -2, 2]*10^8);
    drawnow;
end
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In this example, we simulate the motion of three bodies: the Earth, the Moon, and a test particle. We start by setting the initial conditions for their positions and velocities, as well as their masses and the gravitational constant. Then, we enter a loop where we compute the acceleration of each body based on the gravitational force from the other bodies, and update their positions using the Verlet algorithm. We also update the velocities using the central difference method, and plot the current positions at each time step.

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