Positive Window-Sample Constraint

For each window sample, $h\left(n\right) \geq 0$ , or,

$$-h\left(n\right) \leq 0.$$ (4.66)

Stacking inequalities for all $n$ ,

$$\left[\begin{array}{ccccc} -1 & 0 & \cdots & 0 & 0\\ 0 & -1 & & & 0\\ \vdots & & \ddots & & \vdots \\ 0 & & & -1 & 0\\ 0 & 0 & \cdots & 0 & -1\end{array} \right]\left[\begin{array}{c} h\left(0\right)\\ h\left(1\right)\\ \vdots \\ h\left(L-1\right)\\ h\left(L\right)\end{array} \right] \le \left[\begin{array}{c} 0\\ 0\\ \vdots \\ 0\\ 0 \end{array} \right]$$ (4.67)

or

$$\zbox {-\mathbf{I}\, h \le 0.}$$ (4.68)