Hey there.

Currently, I’m working on obtaining relevant stress components. I did so with this small code, where I calculate Sigma_rz and Sigma_thetaz.

```
G = 1 #constant
gradu = nabla_grad(u)
V = FunctionSpace(mesh, 'CG', 1)
uxp = project(gradu[0],V)
ux = uxp.compute_vertex_values(mesh) #esto ya es un vector escalar con un orden predeterminado, serie de números
uyp = project(gradu[1],V)
uy = uyp.compute_vertex_values(mesh) #esto ya e sun vector escalar con un orden predeterminado, serie de números
x = mesh.coordinates()[:,0]
y = mesh.coordinates()[:,1]
sigmarz = G * np.true_divide(np.multiply(ux,x),np.sqrt(np.multiply(x,x)+np.multiply(y,y))) + G * np.true_divide(np.multiply(uy,y),np.sqrt(np.multiply(x,x)+np.multiply(y,y)))
sigmathetaz = np.true_divide(G,np.sqrt(np.multiply(x,x)+np.multiply(y,y))) * (np.multiply(ux,-y) + np.multiply(uy,x))
```

u being a scalar, means gradu is a vector. ux and uy are vectors which components are scalars, so sigmarz and sigmathetaz are vectors with scalars inside too. I’d like to plot this sigmarz and sigmathetaz as a surface. My mesh is created with GMSH.

My question is, how can I know which node is related to any sigma component? How can I know that sigma component 253 (e.g) is calculated in ( x = _, y = _)?

Thanks in advance.