draw a mesh by entering elements and nodes by Location

Having matrix of different nodes with their location, how we can plot a mesh and exert a code on the nodes?

Imagine there are 4 differet type of nodes, with index number of 1,2,3 and 4, total number of 16. A very simple material matrix can be for instance : M=[1,1,1,1,1,1,1,2,2,3,4,4,4,4,4,4], and the corresponding location matrixs are: x=[0.1, 0.2, 0.3, 0.4, 0.2, 0.3, 0.4, 0.2, 0.3, 0.4, 0.2, 0.3, 0.4] and y=[0.1, 0.1, 0.1, 0.1, 0.2, 0.2, 0.2, 0.3, 0.3, 0.3, 0.4, 0.4, 0.4]. So this domain is the following where the numbers are different type of nodes.

So, how this input can be applied in matlab?

Answer 1

[Vinayak Gupta]

Hi Sara,

To my understanding, you want to create a mesh plot for a set of nodes with their given location (in X, Y).

Taking your example, you need to pre-process the given arrays into a set of three matrices as the mesh function requires. You can read about mesh function here.

Also, the arrays in your question were not appropriately sized as M has 16 elements, while the others have 13 elements, respectively. I have assumed values based on the image attached.

M= [1,1,1,1,1,1,1,2,2,3,4,4,4,4,4,4]; 
x= [0.1, 0.2, 0.3, 0.4, 0.1, 0.1, 0.1, 0.2, 0.3, 0.4, 0.2, 0.3, 0.4, 0.2, 0.3, 0.4]; 
y= [0.1, 0.1, 0.1, 0.1, 0.2, 0.3, 0.4, 0.2, 0.2, 0.2, 0.3, 0.3, 0.3, 0.4, 0.4, 0.4]; 

Assuming x and y represent locations, we will convert these into a mesh grid of unique and sorted values. We require sorted values to plot data sequentially and avoid unnecessary folds

X = unique(x); 
Y = unique(y); 
[X, Y] = meshgrid(X, Y); 

Now, we will create a matrix Z of the same size as X and Y. And then fill in the values of M according to their positions. Z will be our nodal matrix.

Z = zeros(size(X)); 
for i=1:16 
    Z(X == x(i) & Y == y(i)) = M(i); 
end 

Now, we have the required three matrices, and we can pass them to the mesh function.

mesh(X, Y, Z); 

And we should get an output figure as this one.