@Rouben Rostamian  

Dear Rouben Rostamian  I agree with your suggestions to give more details about my program. Apparently, the development of a finite element beam for structure analysis has reported by many researchers. The idea behind this program is to understand how to develop the stiffness matrix based on interpolation functions. For instance, if we want to increase the accuracy of the finite element method we can add new terms to displacement function and following the same procedure as given in this program. 

@Rouben Rostamian  

I am grateful for your suggestions and valuable comments. The main purpose of this program is to implement the stiffness matrix method of the Euler-Bernoulli beam and that is clear to those who have studied the finite element method. It is not about to solve an equation. it is to set a procedure for the construction of the stiffness matrix method.