I would like to get a feeling in working with Sacado, and would like to try it
on example 15. According to my understanding I now have to treat the boundary
conditions on my own, and not by using the ConstraintMatrix. Is that still
true, or was there an update since 2008?
I suspect that you are referencing a particular comment in step-33, but it's
been so long that I can't recall what that program does. Can you point out
what you have in mind?
In general, as long as you have Dirichlet boundary conditions, they can be
handled by ConstraintMatrix at the time when the local matrix is distributed
into the global matrix, and that happens after all of the Sacado magic happens
-- you get the local matrix out of Sacado and then copy it into the global matrix.
Furthermore, now the function F() is depending on the gradient of u, and not
as in example 33 depending on u, else it should look like exactly in example
33 (in both examples we have \nabla F(u)). Is that correct? Nevertheless I
assume that I need the numerical flux function due to having to check the
dangling nodes.
You can also handle hanging nodes as is always done, via ConstraintMatrix.
step-33 does it differently not because that is necessary but because the
author decided that he could.
I think that using Sacado (or in general, automatic differentiation) should be
relatively straightforward in step-15, in particular because the residual is
already computed there. I'd just give it a try and see what is necessary. You
may want to use the current developer version of deal.II -- there have been
numerous changes in recent weeks to make AD easier to use in the FEValues
class, in particular through functions such as
FEValues::get_function_{values,gradients}.
Using AD in step-15 is an interesting project. If you make it work, would you
mind sending the assembly function to the mailing list? I think it would make
for a great section in the "Possibilities for extensions" section of step-15!
Best
W.
--
------------------------------------------------------------------------
Wolfgang Bangerth email: [email protected]
www: http://www.math.colostate.edu/~bangerth/
--
The deal.II project is located at http://www.dealii.org/
For mailing list/forum options, see
https://groups.google.com/d/forum/dealii?hl=en
---
You received this message because you are subscribed to the Google Groups "deal.II User Group" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
