use Gauss-Jordan to find the inverse

Gauss-Jordan :"solve two equations at once"

steps:

         1.write down the identify matrix(单位矩阵) on the right side of matix A to get the augmented matrix(增广矩阵).

         2.eliminant the augmented matrix to be a matrix which consists an identify matrix and A inverse.

        Eliminant  procedure is like pivot eliminantion.

        Idea:start with the long matrix(augmented matrix),double length AI,eliminate,eliminate until the left part is down to I,then right part will be A inverse.

        Explain：we suppose that the eliminantion procedure is EAI,then we konw EAI=I?,so, EA=I,so E=A'.?=EI=E=A'.so the right part is A'.

        finish