\begin{align}
J(x) = \sum\limits_{i = 1}^n {w(x - {x_i}){{({u^h}(x) - u({x_i}))}^2} = \sum\limits_{i = 1}^n {w(x - {x_i}){{({P^T}({x_i})a(x) - u({x_i}))}^2}} },  
\end{align}