### vector derivative returns a scalar

Trying to obtain the derivative of $\vec{u} = [-1,1]$ using the following code:

u = matrix(1,2,[-1, 1])

r = derivative(u,x);
r

I get a scalar value 0.

Although according the following relation it should be a 2-dimensional zero vector.

$$\frac{\mathrm{d} \vec{u}}{\mathrm{d} x} =\frac{\mathrm{d}}{\mathrm{d} x} [-1, 1] = [ \frac{\mathrm{d}}{\mathrm{d} x}(-1), \frac{\mathrm{d}}{\mathrm{d} x}(1) ] = [0, 0]$$

Why does it happen? In the case it's a bug where could I ~~could ~~report it?

Thanks