Justin Chang writes:
> Pardon me for my apparent lack of understanding over what may be simple
> concepts, but why is div[u]*div[v] singular in the context of LSFEM?
The corresponding strong form is grad(div(u)). If u has n*d entries (in
d dimensions -- it is a vector), div(u) has only n entrie
Pardon me for my apparent lack of understanding over what may be simple
concepts, but why is div[u]*div[v] singular in the context of LSFEM?
On Fri, Dec 11, 2015 at 12:15 PM, Jed Brown wrote:
> Justin Chang writes:
>
> > Jed,
> >
> > 1) What exactly are the PETSc options for CGNE?
>
> -ksp_type
Justin Chang writes:
> Jed,
>
> 1) What exactly are the PETSc options for CGNE?
-ksp_type cgne
(Conjugate Gradients on the Normal Equations)
> Also, would LSQR be worth trying? I am doing all of this through
> Firedrake, so I hope these things can be done directly through simply
> providing c
Jed,
1) What exactly are the PETSc options for CGNE? Also, would LSQR be worth
trying? I am doing all of this through Firedrake, so I hope these things
can be done directly through simply providing command line PETSc options :)
2) So i spoke with Matt the other day, and the primary issue I am hav
Justin Chang writes:
> So I am wanting to compare the performance of various FEM discretization
> with their respective "best" possible solver/pre conditioner. There
> are saddle-point systems which HDiv formulations like RT0 work, but then
> there are others like LSFEM that are naturally SPD and
Yes you are correct matt
On Saturday, November 28, 2015, Justin Chang wrote:
> So I am wanting to compare the performance of various FEM discretization
> with their respective "best" possible solver/pre conditioner. There
> are saddle-point systems which HDiv formulations like RT0 work, but then
So I am wanting to compare the performance of various FEM discretization
with their respective "best" possible solver/pre conditioner. There
are saddle-point systems which HDiv formulations like RT0 work, but then
there are others like LSFEM that are naturally SPD and so the CG solver can
be used (
On Sat, Nov 28, 2015 at 10:35 AM, Patrick Sanan
wrote:
> On Sat, Nov 28, 2015 at 06:31:31AM -0600, Matthew Knepley wrote:
> > On Sat, Nov 28, 2015 at 12:10 AM, Justin Chang
> wrote:
> >
> > > Hi all,
> > >
> > > Say I have a saddle-point system for the mixed-poisson equation:
> > >
> > > [I -gr
On Sat, Nov 28, 2015 at 06:31:31AM -0600, Matthew Knepley wrote:
> On Sat, Nov 28, 2015 at 12:10 AM, Justin Chang wrote:
>
> > Hi all,
> >
> > Say I have a saddle-point system for the mixed-poisson equation:
> >
> > [I -grad] [u] = [0]
> > [-div 0 ] [p] [-f]
> >
> > The above is symmetric
On Sat, Nov 28, 2015 at 12:10 AM, Justin Chang wrote:
> Hi all,
>
> Say I have a saddle-point system for the mixed-poisson equation:
>
> [I -grad] [u] = [0]
> [-div 0 ] [p] [-f]
>
> The above is symmetric but indefinite. I have heard that one could make
> the above symmetric and positive
Hi all,
Say I have a saddle-point system for the mixed-poisson equation:
[I -grad] [u] = [0]
[-div 0 ] [p] [-f]
The above is symmetric but indefinite. I have heard that one could make the
above symmetric and positive definite (SPD). How would I do that? And if
that's the case, would this
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