solve 3 order differential equations

error : Not enough input arguments.

MATLAB code:

function dx = eq62(t,x)

u = -(2*x(2)-8*x(1)+6*x(3)+8*x(1)*x(3)-(x(3)-2)*(x(1)-x(2)+x(3))+x(1)*(x(1)-1))/(x(1)+1);

dx = [-x(1)+x(2)-x(3);-x(1)*x(3)-x(2)+u;-x(1)+u]

how yo solve this problem , thanks

Answer 1

[Star Strider]

Without seeing your ODE solver call, I cannot determine what the problem is.

This runs without error for me (in R2020b):

    function dx = eq62(t,x)
    u = -(2*x(2)-8*x(1)+6*x(3)+8*x(1)*x(3)-(x(3)-2)*(x(1)-x(2)+x(3))+x(1)*(x(1)-1))/(x(1)+1);
    dx = [-x(1)+x(2)-x(3);-x(1)*x(3)-x(2)+u;-x(1)+u];
    end


[t,x] = ode45(@eq62, [0 5], [0 0 1]);

figure
plot(t,x)
grid

.