Spectral stochastic finite element method: 2D plane stress example

Solution of the plane stress example proposed in Sec. 5.3 of the book by Ghanem and Spanos'

A 2D plane stress solid with uncertain elasticity modulus and subjected to deterministic distributed load is analyzed by the spectral stochastic finite element method. This reference example is described in Sec.(5.3): "Stochastic finite elements: A spectral approach" by Ghanem and Spanos.
The main function 'main_ssfem_plate.m' contains a step-by-step solution of this problem. Several references to equations and useful comments are written in order to provide a better understanding of the code. The program estimates for a number terms in the Karhunen-Loève expansion (variable 'KLterms') and a given order of the polynomial chaos (variable 'p_order'), the mean and standard deviation displacement response fields; also the corresponding PDF and CDF of the displacement at a given degree of freedom of the solid. The folder 'result_MCS' contains a .txt file with the solution obtained by the Monte Carlo simulation method for comparison purposes.
A complete description of the method is in:
http://www.bdigital.unal.edu.co/51037/

It is worth mentioning that another implementation of this example can be found in the FERUM software http://www.ce.berkeley.edu/projects/ferum/Download/download.html

Any suggestions, corrections and/or improvements will be kindly accepted :-)