对于Lagrange正六面体高阶单元，若三个坐标方向上的节点划分数分别为p,q,r,则该单元位移模式的最高阶多项式的阶次为
Regarding the use of Lagrange regular hexahedron higher-order elements: if the number of nodes is divided into the three coordinate directions respectively p, q, r, the highest polynomial order of element displacement model is