四节点等参元的matlab程序，可用于平面单元的有限元计算-four_node_quadrilateral_isoparametric_element matlabcode

基于有限元基本原理，利用matlab编写了平面4节点实体单元的程序，可以更加了解4节点有限元的基本理论。(Based on the basic principle of finite element method, the program of plane 4 node solid element is written by MATLAB, which can better understand the basic theory of 4 node finite element.)