说明：  用有限元分析的法解决一类偏微分方程，用到的DG方法，绝对原创。Ut=Uxx,with U(x,0)=sin(x)
(Finite element analysis using the method to solve a class of partial differential equations, using the DG method, an absolute original. Ut = Uxx, with U (x, 0) = sin (x))