I write this, but I don't know how I can do rest of it.

Consider the nonlinear system of three first order differential equations 

(The Lorenz Attractor): 

diff(x)=10(y-x) 
diff(y)=-xz+28x-y 
diff(z)=xy-8z/3 

a) ( 25 pts.) Write the function to solve the system which will be called through ode23. Please provide the function code.

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dy = zeros(3,1);
dy(1) = 10*(y(2) - y(1));
dy(2) =  - y(1)*y(3) + 28*y(1) - y(2);
dy(3) = y(1)*y(2)-(8/3)*y(3);
end

I write this, but I don't know how I can do rest of it.