# oc.optimization and control – Minimize expression under constraint, that solution must be positive

I want to calculate $$vec{x}$$ such that the expression
$$lVerthat{A} vec{x} – vec{B}rVert²$$
shall be minimized under the constraint, that each component $$x_i$$ of the vector $$vec{x}$$ shall be positive.

I tried it with Lagrange-multipliers, but I didn’t know how to formulate the constraint, since I only came up with $$x_i = vert x_ivert$$, which isn’t a function $$mathbb{R}^n to mathbb{R}$$, which I would need (as far as I understood).

It would be great, if you could help me.