Why am I getting an error on this?

Why am I getting an error that says "Not enough input arguments."

function dydx = funct(x, y, z)
    a = 1;
    b = 2;
    c = 3;

    dydx = a*y + b*z + c*x;
end

y0 = 1;
z0 = 2;

[x, y] = ode45(@funct, [0, 10], [y0, z0]);

plot(x, y);

[Bora Eryilmaz]

func() takes 3 scalar arguments (x, y, z), but you are passing a single vector argument ([y0, z0], etc.) to it.

[Torsten]

If you want to solve for two unknown functions (y and z), you need two differential equations, not only one.