@Rouben Rostamian  Thanks a lot

@ Thanks a lot tomleslie 

@Kitonum 

Thanks a lot.

I find another method 

Dear Kitonum, 

Thanks a lot, I really appreciate your answer. 

But the Maple only plots four points. I need every side of the square consist of 100 points. So I need to discretize the length between any two points of the square to a pair as (x_[i], y_[i]) and plot these point.

@Kitonum   Thanks a lot

@vv Thanks a lot. It works in my program.

@Adri van der Meer Thanks a lot, it works.

@tomleslie Thanks a lot.

@Kitonum Thanks a lot

@Axel Vogt Thanks a lot

@Preben Alsholm Thanks a lot, Your answers help me a lot to find a numerical solution for these system of PDEs.

Really, i am very grateful to you.

Amr

@Preben Alsholm 

By choosing the parameter eta<<1. the program gives a good resluts.

I would like to knew how to draw the resluts in three dimension (function, x,t).

@Preben Alsholm Thanks for your reply.

By change the function R(x,t) to its derivatives in x. It works.

But, These equations has a physical meaning and change is not possible here.

@tomleslie : Here is the new image. All the quantities in the matrices are defined.

Here is the Image for the error........