!本程序主要用来解决二维平面应力弹性问题（带厚度），在f90上调试通过。

!包含主程序STRESS和三个字程序ELSTMX(KK)、MODIFY、DCMPBD和SLVBD

!主程序主要进行基本的输入输出以及最大半带宽的计算，组装总体刚度矩阵计算的应力应变值

!子程序elstmx(kk)计算刚度系数矩阵，生成第kk单元的刚度矩阵k

!子程序MODIFY输入节点的集中力，边界节点的位移，对总体刚度矩阵和位移数组和节点力数组作修改

!子程序DEMPBD用高斯消元法将半带宽的矩阵变成上三角阵

!子程序SLVBD为总体矩阵的回代求位移向量-! The program is mainly used to solve the two-dimensional plane stress elasticity problems (with thickness), the f90 debugging through. ! Contains the main STRESS and words program ELSTMX (KK), MODIFY, DCMPBD and SLVBD! Main program for basic input-output and maximum half bandwidth calculation, the overall stiffness matrix assembly calculated stress and strain values! Subroutine elstmx ( kk) calculate the stiffness coefficient matrix to generate a first kk element stiffness matrix k! subroutine MODIFY input node of concentration, the displacement boundary nodes, the overall stiffness matrix and nodal force and displacement array array modified! subroutine DEMPBD using Gaussian elimination element method for the semi-bandwidth matrix becomes upper triangular matrix! subroutine SLVBD overall matrix for the displacement vector DD back intercessions