# 9 node mesh generation

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Lokesh Mangal on 9 Jan 2020
Answered: Sai Sri Pathuri on 13 Jan 2020
how we can convert the dotted figure in to another figure shown below? To get 9 node mesh.
%% code to get dooted figure
clc ; clear;
% Dimensions of the plate
L = 1 ; % Length of the Plate along X-axes
B = 1 ; % Breadth of the Plate along Y-axes
% Number of Elements required
Nx = 4 ; % Number of Elements along X-axes
Ny = 4 ; % Number of Elements along Y-axes
%----------------------------------------
nel = Nx*Ny ; % Total Number of Elements in the Mesh
nnel = 9 ; % Number of nodes per Element
% Number of points on the Length and Breadth
npx = 2*Nx+1 ;
npy = 2*Ny+1 ;
nnode = npx*npy ;
nx = linspace(0,L,npx) ;
ny = linspace(0,B,npy) ;
[xx yy] = meshgrid(nx,ny) ;
% To get the Nodal Connectivity Matrix
coordinates = [xx(:) yy(:)] ;
plot(xx,yy,'b.','MarkerSize',10)
xx(:,[2 4 6 8]) = [];
yy([2 4 6 8],:)=[];
coordinates1 =[xx(:) yy(:)] ;
x = coordinates1(:,1);
y = coordinates1(:,2);
hold on
plot (x,y,'r*')

Sai Sri Pathuri on 13 Jan 2020
The line function can be used to draw the lines between the dots.
for i = 0.25 : 0.25 : 0.75
line([i i],[0 1],'LineStyle','-','Color','black') % To draw vertical lines
line([0,1],[i i],'LineStyle','-','Color','black') % To draw horizontal lines
end