Fórmula 17

D = [\begin{matrix} D_{11} & D_{12} & 0 & 0 & 0 & 0 & 0 & 0 \\ D_{22} & 0 & 0 & 0 & 0 & 0 & 0 \\ D_{33} & 0 & 0 & 0 & 0 & 0 \\ D_{44} & 0 & 0 & 0 & 0 \\ D_{55} & 0 & 0 & 0 \\ sym & D_{66} & 0 & 0 \\ D_{77} & 0 \\ D_{88} \end{matrix}]

;