Re: [Getfem-users] Build a mesh with quadrature points

[Giovani]

Julien

Thank you very much! That piece of code is helping a lot!

If I may ask, I have another issue that requires enlightenment:

Suppose you have a getfem::mesh, a getfem::mesh_fem linked with the 
mesh, and a point in global coordinates whose location is not identical 
to any of the mesh nodes. This point is, however, inside the object that 
the mesh represents, so I can interpolate data from the mesh nodes to it.

--> How can I evaluate the shape functions of a single, specific 
getfem::mesh_fem dof at this point's coordinates?

--> If I multiply the result from the previous question by the value of 
a field prescribed at that dof, I'll then have the contribution of that 
dof to the interpolation of the field at the point. Just to be sure, 
this result will be normalized, right? I mean, if I repeat this for all 
dofs and simply sum the results, I'd obtain the same interpolation that 
I'd get if I used getfem::interpolation instead, although this explicit 
sum is probably more computationaly expensive than using 
getfem::interpolation. Is that it?

Best regards,

Giovani




julien pommier escreveu:
> Hi Giovani,
> If you want to retrieve the coordinates of the quadrature points of a 
> convex cv, you can do:
>
>    /* get the approximate integration method for the convex */
>    getfem::papprox_integration pai
>      = mim.int_method_of_element(cv)->approx_method();
>    /* prepare the geotrans_interpolation_context to apply the 
> geometric transformation */
>    bgeot::base_matrix G;
>    bgeot::vectors_to_base_matrix(G, m.points_of_convex(cv));
>    bgeot::geotrans_interpolation_context c(m.trans_of_convex(cv),
>                        pai->point(0), G);
>    /* apply the geotrans to each point of the integration method */
>    for (size_type j = 0; j < pai->nb_points_on_convex(); ++j) {
>      c.set_xref(pai->point(j));
>      std::cout << " integration node " << j << " for convex " << cv << 
> " is " << c.xreal() << "\n";
>    }
>
> Best regards,
> Julien
>
> Giovani wrote:
> > Good day  gentlemen!
> >
> > Suppose I have a getfem::mesh object that has a getfem::mesh_fem 
> > linked to it, and also a getfem::mesh_im that's also linked.
> >
> > I would like to build a new getfem::mesh, whose nodes are located at 
> > the quadrature points of the previous mesh. Is there any simple way 
> > of retrieving a list with the global coordinates of those quadrature 
> > points?
> >
> > Best Regards,
> >
> > Giovani M. Faccin
> >
> > _______________________________________________
> > Getfem-users mailing list
> > address@hidden
> > https://mail.gna.org/listinfo/getfem-users