Week 3 - Solving second order ODEs

clear all
close all

b=0.05
g=9.81
l=1
m=0.1

%intial condition time and displacement
theta_0 =[0 ; 3];

%time point

t_span = linspace(0,20,500);

%solve ODE

[t,results] = ode45( @(t,theta) ode_func(t,theta,b,g,l,m),t_span,theta_0);

displacement = results(:,1);

velocity = results(:,2);

%plotting time Vs result (displacement,angular velocity)

figure (1)

plot(t,displacement);

hold on

plot(t,velocity);


ylabel('plot')
xlabel('time')



%plotting pendulum motion


displacement = results(:,1);

velocity = results(:,2);

ct =1;

for i = 1:length(displacement)

    string_disp =  displacement(i)

    x0 = 0;
    y0 = 0;

    x1 = l*sin(string_disp);

    y1 = -l*cos(string_disp);

    figure (2)

    plot ([x0 x1],[y0 y1],'Color','g','LineWidth',2);

    hold on

    plot (x1,y1,Marker='o')

    hold off

    axis([-2 2 -2 2]);

     
    pause(0.05)

    M(ct) = getframe(gcf);

    ct = ct + 1;

end

movie (M)

videofile = VideoWriter('Pendulum_motion.avi','Uncompressed AVI');

open(videofile);
writeVideo(videofile,M)
close(videofile)