ODE for Pendulum motion

% main body
close all
clear all
clc

t = [0 20]
yo = [0 3]

[t, y] = ode45(\'ode_pendulum\',t,yo)

subplot(5,4,[13,14,15,16]);
plot(t,y(:,1),\'color\',\'r\');
hold on;
plot(t,y(:,2),\'color\',\'b\');
hold off;
subplot(5,4,[17,18,19,20]);
plot(y(:,1),y(:,2));
xlabel(\'position_Radians\')
ylabel(\'Angular_velocity\');

ct=1;
for i=1:length(y(:,1))
    x0=0;
    y0=0;
    x1=1*sin(y(i,1));
    y1=-1*cos(y(i,1));
    subplot(5,4,[1,2,3,4,5,6,7,8,9,10,11,12]);
    plot([-1 1],[0 0],\'linewidth\',4,\'color\',\'k\');
    hold on
    line([x0 x1],[y0,y1],\'linewidth\',2,\'color\',\'b\');
    hold on;
    plot(x1,y1,\'-o\',\'markers\',20,\'markerfacecolor\',\'r\');
    
    grid on;
    axis([-1.5 1.5 -1.5 1.5])
    pause(0.03);
    hold off
    %q(ct)=getframe(gcf);
    text=sprintf(\"pendulum%d.png\",ct);
    saveas(1,text);
    ct=ct+1;
end

% function 

function [ydot] = ode_pendulum(t,y);

b = 0.05;
L = 1;
M = 1;
g = 9.81;

ydot = zeros(2,1);

ydot(1) = y(2)

ydot(2) = -((b/M)*y(2))-(g/L)*(sin(y(1)))

end