On Mon, 27 Feb 2012, David Knezevic wrote:

> I've just checked in the discontinuous Lagrange basis (L2_LAGRANGE) we
> discussed recently. Changing MONOMIAL to L2_LAGRANGE in
> miscellaneous_ex5 works fine in both 2D and 3D.

Thanks!

> 1. Just like in fe_monomial.C, I set compute_constraints to be a NOOP. I
> was surprised to see that this method is not a NOOP in L2_HIERARCHIC?

compute_proj_constraints would work correctly (it just does an
immediate return for DISCONTINUOUS), it's just slightly less efficient
to call it needlessly.  This looks like a minor oversight.

> 2. Similarly, I was surprised to see that L2_HIERARCHIC returns C_ZERO
> rather than DISCONTINUOUS in get_continuity()?

This looks just wrong.  Could cause lots of subtle breakage.  Unless
there's something I'm missing - Truman?

> 3. In fe_monomial.C, it looks like monomial_n_dofs() and
> monomial_n_dofs_per_elem() are identical? If so, I'd like to delete the
> latter (we only have one of these two functions in L2_HIERARCHIC and
> L2_LAGRANGE)

Agreed; go right ahead.

> 4. For now I've just used the same "max_order" for L2_LAGRANGE and
> LAGRANGE, since I wanted to do an initial check-in based directly on
> LAGRANGE. But L2_LAGRANGE's Order is no longer related to "element
> order" (e.g. a SECOND on a TRI3 is perfectly fine for L2_LAGRANGE), so
> those extra valid combinations could be added to L2_LAGRANGE... this
> would also have implications for the serendipity shapes functions: we
> currently assume that QUAD8 or HEX20 implies serendipity, but this need
> not be true with L2_LAGRANGE.

Right - max_order==unlimited would be fine once the default n >
hand-coded case is handled in the shape function calculations.

> 5. I followed the L2_HIERARCHIC approach of adding new files
> fe_l2_lagrange_shape_*D.C which are copies of fe_lagrange_shape_*D.C
> with LAGRANGE replaced by L2_LAGRANGE. But it would be possible to just
> call LAGRANGE's shape functions directly, rather than copying and
> pasting --- though this would need some modifications if point 4 above
> is implemented. Any thoughts on the best thing to do here?

I'm fine with the copy/paste if others are - especially given that the
codes may diverge soon to add those higher-order features.
---
Roy

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