We denote $\mathcal{I} = \{(j, k) \in \mathbf{N}^{2} \mid j \in \mathbf{N} \text{ and } 0 \leq k < 2^{j}\}$. For all $(j, k) \in \mathcal{I}$,
$$c_{j,k}(f) = f\left(\left(k + \frac{1}{2}\right) 2^{-j}\right) - \frac{f(k 2^{-j}) + f((k+1) 2^{-j})}{2} .$$
For all $(j, k) \in \mathcal{I}$, $(i, \ell) \in \mathcal{I}$, calculate $c_{j,k}(\theta_{i,\ell})$.