[firedrake] Second derivatives

[David Ham]

Hi Justin,

Can you provide a little more information about the sort of discretisation
you're talking about: if we can see what you're talking about then we'd be
in a better position to tell you whether Firedrake can do that.

Cheers,

David

On Fri, 17 Jul 2015 at 07:39 McRae, Andrew <a.mcrae12 at imperial.ac.uk> wrote:

>    It's possible to represent second derivatives in a form, such as
> assemble(div(grad(f))*dx).  I assume this is true in FEniCS as well as
> Firedrake, because this is just UFL/FFC/FIAT functionality.  This would
> produce the sum (over cells) of the Laplacian of f on each cell.
>
>  However, like FEniCS, none of our function spaces have more than C^0
> continuity.  That is, the functions are at most continuous, but won't have
> continuous derivatives.  It's likely that you won't want to use second
> derivatives of C^0 functions in a practical discretisation (though I'm sure
> there are methods that *do* do this).
>
>  Andrew
>
> On 17 July 2015 at 01:50, Justin Chang <jychang48 at gmail.com> wrote:
>
>> Hi everyone,
>>
>>  Is it possible to do second derivatives? What I mean by that is things
>> like div[grad[u]] and grad[grad[u]]. I haven't tried this out yet, but we
>> use these discretizations a lot for our research, and FEniC's inability to
>> do this made us sad (although our more major qualms had to do with its
>> inability to support quads).
>>
>>  Thanks,
>> Justin
>>
>>
>
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