symbolic animation in matlab

main.m
syms t g L theta(t)  % define symbolic variables
ode = diff(theta, t, 2) == -g/L*sin(theta);  % define pendulum ODE
cond = [theta(0) == pi/6, diff(theta)(0) == 0];  % specify initial conditions

% solve ODE symbolically and convert to function handle
thetaSol = dsolve(ode, cond);
thetaFun = matlabFunction(thetaSol);

% set up plot axis and objects
axis([-1.5*L 1.5*L -1.5*L 1.5*L]);
rod = line('XData', [0 0], 'YData', [0 0], 'Color', 'b', 'LineWidth', 2);
bob = line('Marker', 'o', 'MarkerSize', 10, 'MarkerFaceColor', 'r', 'MarkerEdgeColor', 'none');

% define time vector and loop over each frame
tVec = linspace(0, 10, 200);
for i = 1:length(tVec)
    thetaVal = thetaFun(tVec(i));
    xBob = L*sin(thetaVal);
    yBob = -L*cos(thetaVal);
    set(rod, 'XData', [0 xBob], 'YData', [0 yBob]);
    set(bob, 'XData', xBob, 'YData', yBob);
    drawnow;
end
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