Phase plot adding direction arrows

Hi, need some help regarding adding arrows in velocity plot. So my current plot based on the script extract below yields, the "angular velocity graph" (Don't mind the axis name its suppose to be theta), is there a way to add arrows for the velocity directions? I'm visualizing of something like the second image below.

clear all, close all, clc

m = 0.25;
M = 0.635;
l = 0.5;
g = -9.81;
b = 1;

tspan = 0:.001:50;
y0 = [0; -.01; -pi; 0];
[t,y] = ode45(@(t,y)Equation(y,m,M,l,g,b,0),tspan,y0);
g = y(:,3);

figure(2);
plot(y(:,3),y(:,4));
title('Angular Velocity Graph')
xlabel('Time (s)')
ylabel('Angular Velocity (rad s^{-1})')

function dy = Equation(y,m,M,l,g,b,u)

    Sinx = sin(y(3));
    Cosx = cos(y(3));
    a = ((M+m)*l-m*l*Cosx^2);

    dy(1,1) = y(2);
    dy(2,1) = (u*l-b*y(2)*l-m*g*l*Cosx*Sinx+m*l^2*y(4)^2*Sinx)/a;
    dy(3,1) = y(4);
    dy(4,1) = (g*Sinx*(M+m)+Cosx*b*y(2)-Cosx*u-m*l*y(4)^2*Sinx*Cosx)/a;

end

[David Martin]

I have the same question. An eextensive search has come up with nothing.

I have tried quiver, and it has failed. I have tried adding '->' linespec to the plots, but the triangles were all pointing in the same direction.

I tried annotation arrow, but it only accepts two vectors with two elements as inputs for x and y.