%pendulum equation
a=0;b=pi/2;%integration interval
g=9.8;%accelaration due to the gravity
L=0.1;%length of the pendulum
y0=[0,0.1];%initial conditions
options=odeset('RelTol',1e-8);%modify the options
%use the solver
[t,y]=ode45('fPendul',[a,b],y0,options,g,L)
plot(t,y(:,1));