This function generates rectangular mesh accoarding to grid set by vectors xx and yy.
function [Nodes, Rectangles]=Rectangles_Mesh(xx,yy)
xx and yy are vectors for grids of size (Nx,1) and (Ny,1), respectively.
Nodes (Nx*Ny,2) is a matrix of x-coordinate of y-coordinates of the mesh nodes.
Rectangles((Nx-1)*(Ny-1),4) is a matrix of nodes connectivity for each element in counter clockwise direction.
Ayad Al-Rumaithi (2020). Generate Rectangular Mesh (https://www.mathworks.com/matlabcentral/fileexchange/74656-generate-rectangular-mesh), MATLAB Central File Exchange. Retrieved .