使用有限单元法计算常应变三角形单元的刚度矩阵，输入为个节点的坐标，以及模型的材料参数，输出为分析模型的刚度矩阵。-Using the finite element method to calculate constant strain triangular element stiffness matrix, enter the coordinates of nodes, as well as the material parameters of the model, the output sti