ODE: How can I trace changing of all parts of equation during solving

Hello! I'll be grateful if someone could help me. So the question is:

I have an ODE that is been solved correctly.

function [out] = chua(t,in,alpha, beta, A, C, u1st)

x = in(1);
y = in(2);
z = in(3);

xdot  = -alpha*((3*A*u1st^2+C+1)*x-y) ...
      -3*A*alpha*u1st*x^2...
      -A*alpha*x^3;
ydot  = x - y + z;
zdot  = -beta*y;

out = [xdot ydot zdot]';

The call is:

t = [0 2400];
y = [0.004 0 0];

alpha  = 15.6;
beta   = 28; 
A      = 0.002;
C      = -1.3;
u1st = 0.5;

    [t,y] = ode45(@(t, y) chuaModIris(t, y, alpha, beta, A, C, u1st), t, y );
    plot3(y(:,1),y(:,2),y(:,3))     

But on each step of integration I need to get extra data - parts of the first equation:

   SquarePart = -3*A*alpha*u1st*x^2;

and

   CubicPart = -A*alpha*x^3;

Actually, I've already done it in Simulink, but I haven't any idea how to implement it in m-file.

Answer 1

[darova]

What about this?

[t,y] = ode45(@(t, y) chuaModIris(t, y, alpha, beta, A, C, u1st), t, y );
plot3(y(:,1),y(:,2),y(:,3))     

SquarePart = -3*A*alpha*u1st*y(:,1).^2;
CubicPart = -A*alpha*y(:,1).^3;

[Uladzislau]

So obvious, but I haven't seen such simple way! Thank you!!