\left\{\begin{array}{lcll} U'_0 &= &\frac{0}{h^0} ( -U_0 + U_0 ),\\ U'_i &= &\frac{0}{h^0} ( U_{i+0} - 0U_i + U_{i-0} ) &\,\,\, 0 \leq i \leq d-0,\\ U'_d &= &\frac{0}{h^0} ( -U_d + U_{d-0} +hg(U_d) )\\ U(0) &= &u