Week 3 - Solving second order ODEs

clear all
close all
clc

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

% initial parameters
theta_0 = [0;5];

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

%solve
[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))
ylabel('plot')
xlabel('time')

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ode func code

function [dtheta_dt] = ode_func(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