Gradient at ghost cells only?

Matthew Knepley knepley at
Sat Mar 4 11:22:59 CST 2006

I think it would be really useful to look at the DA code first. This has
all the correct structures, but a simple implementation for structured
grids. For instance, the gradient is the action of the Jacobian on a
vector. That is really how it should be coded. You have a bunch of
local actions, and then a global assembly.


On 3/4/06, billy at <billy at> wrote:
> Hi,
> I need the gradient of 5 scalars at ghost cells and I was thinking of
> creating
> 5x3 vectors with VecCreateGhost(). Right now, I calculate the gradient
> during
> each iteration and I don't store it's value.
> I would like to calculate, store and exchange the gradient at the ghost
> cells
> only, to minimize memory requirements. How is the best way to do that?
> Billy.

"Failure has a thousand explanations. Success doesn't need one" -- Sir Alec
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