Week 3 - Solving second order ODEs

function [dtheta_dt] = ode_fun(t,theta,b,g,l,m)
theta1 = theta(1);
theta2 = theta(2);
dtheta1_dt = theta2;
dtheta2_dt = -(b/m)*theta2 - (g/l)*sin(theta1);
dtheta_dt = [dtheta1_dt; dtheta2_dt];
end

clear all
close all
clc

b = 0.5;
g = 9.81;
l = 1;
m = 0.1;

%initial condition
theta_0 = [0;5];

% time points
t_span = linspace(0,10,500);

%solve ODE
[t, results] = ode45(@(t,theta) ode_fun(t, theta, b,g,l,m),t_span, theta_0);

plot(t,results(:,1))
hold on
plot(t,results(:,2))
ylabel('plot')
xlabel('time')