[petsc-users] basis functions of high order approximation (FE)

[Jed Brown]

Yes, tensor product of Lagrange polynomials, often written as Q_k.
Degrees of freedom associated with Dirichlet boundary conditions have
been removed in the systems you're looking at.

Yann Jobic via petsc-users <petsc-users at mcs.anl.gov> writes:

> Dear Petsc Users,
>
> I've been playing with the option "space_degree", in 2D, for a space 
> discretisation of 4 cells (2x2), for a poisson problem, and i wonder 
> what are the underlying concepts.
>
> With a space degree 2, i get a    9x9   algebraic system, and i've got a 
> solution convergence order of 3.
>
> With a space degree 3, i get a 25x25 algebraic system, and i've got a 
> solution convergence order of 4.
>
> So my question is : what are the basis functions associated with each 
> space degree ?
>
> Are they lagrange polynomials or something else ?
>
> Thanks!
>
> Yann