Week 3 - Solving second order ODEs

clear all

close all

clc

L=1;

m= 0.1;

b=0.05;

g=9.81;

% initial condition

theta_0 = [0;3];

% time points

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);

plot(t,results(:,1))

hold on

plot(t,results(:,2))

xlabel('time')

ylabel('plot')

function of the ODE function:

function [dtheta_dt] = ode_func (t,theta,b,g,l,m)

theta1 = theta(1)

theta1 = theta(2)

dtheta1_dt = theta2;

dtheta2_dt = -(b/m)*theta2 - (g/l)*sin(theta1);

dtheta_dt = [dtheta1_dt; dtheta2_dt];

end