MeshRectangular.m

function [coordinates, nodes,nel,nnode] = MeshRectangular(L,B,Nx,Ny)
% To Mesh a membrane using 4 noded Elements        |    
%--------------------------------------------------------------------------
%--------------------------------------------------------------------------
% Purpose:
%         To Mesh a square/rectangular membrane to use in FEM Analysis
% Synopsis :
%         [coordinates,nodes,nel,nnode] = MeshRectangular(L,B,Nx,Ny)
% Variable Description:
% Input :
%           L  - length of the membrane along X-axes
%           B  - breadth of the membrane along Y-axes
%           Nx - number of Elements along X-axes
%           Ny - number of Elements along Y-axes
% Output :
%           coordinates - The nodal coordinates of the mesh
%           -----> coordinates = [node X Y] 
%           nodes - The nodal connectivity of the elements
%           -----> nodes = [node1 node2......] 
%           nel- total number of elements
%           nnodes- total number of nodes 
%--------------------------------------------------------------------------
nel = Nx*Ny ;        % Total Number of Elements in the Mesh
nnel = 4 ;           % Number of nodes per Element
% Number of points on the Length and Breadth
npx = Nx+1 ;
npy = Ny+1 ;
nnode = npx*npy ;      % Total Number of Nodes in the Mesh
% Discretizing the Length and Breadth of the membrane
nx = linspace(0,L,npx) ;
ny = linspace(0,B,npy) ;
[xx yy] = meshgrid(nx,ny);
XX=xx;YY=yy;
coordinates = [XX(:) YY(:)];

% To get the Nodal Connectivity Matrix
NodeNo = 1:nnode ;
nodes = zeros(nel,nnel) ;

% small code for selecting nodal point number for specific element
    NodeNo = reshape(NodeNo,npy,npx);
    nodes(:,1) = reshape(NodeNo(1:npy-1,1:npx-1),nel,1);
    nodes(:,2) = reshape(NodeNo(1:npy-1,2:npx),nel,1);
    nodes(:,3) = reshape(NodeNo(2:npy,2:npx),nel,1);
    nodes(:,4) = reshape(NodeNo(2:npy,1:npx-1),nel,1);

%
% Plotting the Finite Element Mesh
% Initialization of the required matrices
X = zeros(nnel,nel) ;
Y = zeros(nnel,nel) ;
% Extract X,Y coordinates for the (iel)-th element
  for iel = 1:nel
      X(:,iel) = coordinates(nodes(iel,:),1) ;
      Y(:,iel) = coordinates(nodes(iel,:),2) ;
  end
%Figure

%    fh = figure ;
%set(fh,'name','Preprocessing for FEA','numbertitle','off','color','w') ;
%patch(X,Y,'w')
%title('Finite Element Mesh of Plate') ;
%axis([0. L*1.01 0. B*1.01])
%axis off ;
%if L==B
%    axis equal ;
%end

nnode = size(coordinates,1) ;        
nel = size(nodes,1) ;