线性四面体元的有限元分析可直接利用的函数，包括求刚度矩阵，求体积，求整体刚度矩阵等，有重要的利用价值-Linear tetrahedral element finite element analysis can be directly used for functions, including seeking stiffness matrix, the volume demand, the global stiffness matrix of such demand, there is significant value in use