Ok thanks so much for the help! It's nice that it coincides with the
easiest option!
On Sat, Jun 11, 2022 at 7:54 PM Matthew Knepley wrote:
> On Sat, Jun 11, 2022 at 8:43 PM Samuel Estes
> wrote:
>
>> I'm sorry, would you mind clarifying? I think my email was so long and
>&g
I'm sorry, would you mind clarifying? I think my email was so long and
rambling that it's tough for me to understand which part was being
answered.
On Sat, Jun 11, 2022 at 7:38 PM Matthew Knepley wrote:
> On Sat, Jun 11, 2022 at 8:32 PM Samuel Estes
> wrote:
>
>> Hello,
&g
Hello,
My question concerns preallocation for Mats in adaptive FEM problems. When
the grid refines, I destroy the old matrix and create a new one of the
appropriate (larger size). When the grid “un-refines” I just use the same
(extra large) matrix and pad the extra unused diagonal entries with
Thank you both so much. That makes sense. It also explains the zero fill option
in the MatPreallocatorPreallocate routine. I believe I understand what I need
to now.
> On Apr 12, 2022, at 4:11 PM, Junchao Zhang wrote:
>
>
>
>
>> On Tue, Apr 12, 2022 at 3:51 PM Samue
because the routine does that for me?
On Tue, Apr 12, 2022 at 3:46 PM Junchao Zhang
wrote:
>
>
> On Tue, Apr 12, 2022 at 12:23 PM Samuel Estes
> wrote:
>
>> Maybe I should create a separate question for this but I did some testing
>> and now I'm a bit confused on how
which entries will be non-zero, PETSc also actually
assigns a zero value under the hood so that I don't have to explicitly
assign values myself. Is this correct?
Sorry for the convoluted question. I hope it's clear.
On Tue, Apr 12, 2022 at 11:54 AM Samuel Estes
wrote:
> Hi,
>
> I have
Hi,
I have a problem where I want to allocate some nonzero structure to a
sparse matrix which will be used repeatedly to solve some equations. The
assembly routines will compress out allocated space which has not been
assigned a value so I know that I need to assign zero values to any unused
Ok thanks! I think I understand now.
On Fri, Apr 1, 2022 at 12:44 PM Matthew Knepley wrote:
> On Fri, Apr 1, 2022 at 1:08 PM Samuel Estes
> wrote:
>
>> Thank you for all the help. I think I'm mostly clear now.
>>
>> I think my only remaining question relates t
PM Samuel Estes
> wrote:
>
>> Ah, so let me see if I understand this now. So basically you preallocate
>> for this "dummy matrix" of type MatPreallocator. But rather than simply
>> calling MatXXXAIJSetPreallocation() to allocate space, you actually tell
>> this
pr 1, 2022 at 11:50 AM Matthew Knepley wrote:
> On Fri, Apr 1, 2022 at 12:45 PM Samuel Estes
> wrote:
>
>> Thanks! This seems like it might be what I need. I'm still a little
>> unclear on how it works though? My problem is basically that for any given
>> row, I know the
there could be a black box utility to figure this out? Am I
misunderstanding how this is used?
On Fri, Apr 1, 2022 at 11:34 AM Matthew Knepley wrote:
> On Fri, Apr 1, 2022 at 12:27 PM Samuel Estes
> wrote:
>
>> Hi,
>>
>> I have a problem in which I know (roughly) the
Hi,
I have a problem in which I know (roughly) the number of non-zero entries
for each row of a matrix but I don't have a convenient way of determining
whether they belong to the diagonal or off-diagonal part of the parallel
matrix. Is there some way I can just allocate the total number of
Great. I think I've got it now. Thanks so much!
On Sun, Feb 6, 2022 at 1:48 PM Matthew Knepley wrote:
> On Sun, Feb 6, 2022 at 2:39 PM Samuel Estes
> wrote:
>
>> First of all, thank you so much for the detailed answers!
>> That clears up most of my confusion. Just to clari
ey wrote:
>
>> On Fri, Feb 4, 2022 at 11:47 PM Samuel Estes
>> wrote:
>>
>>> Hi,
>>>
>>> I have a very basic question about matrix preallocation. I am trying to
>>> use the MatCreate(), MatSetFromOptions(), MatSetPreallocation()
>
Hi,
I have a very basic question about matrix preallocation. I am trying to use
the MatCreate(), MatSetFromOptions(), MatSetPreallocation() paradigm. I
thought that I should use the MatXAIJSetPreallocation() routine since the
code may be run with a SeqAIJ or MPIAIJ matrix but I do not
Hi,
I have a code implementing a finite element method with an adaptive grid.
Rather than destroying the PETSc objects (the Jacobian matrix and RHS
residual vector) every time the code refines the grid, we want to
(over-)allocate some "padding" for these objects so that we only
destroy/create new
Hi,
I am solving a linear system in which the matrix has some block structure.
We will ultimately use the BAIJ format but for now we are just using the
default CSR and would like to play with different formats to compare
performance for our problem. Currently, I call MatSetBlockSize so that I
can
Thanks for the help!
On Fri, Sep 17, 2021 at 11:37 AM Barry Smith wrote:
>
>
> > On Sep 17, 2021, at 12:21 PM, Samuel Estes
> wrote:
> >
> > Hi,
> >
> > I have two related questions about the best way to use the KSP solver:
> >
> > First
Hi,
I have two related questions about the best way to use the KSP solver:
First, I have an adaptive FEM code which solves the same linear system at
each iteration until the grid is refined at which point, obviously, the
size of the linear system changes. Currently, I just call:
Hi,
I have a model in which we alternatively solve two submodels by the finite
element method both on the same unstructured mesh. The first model (call it
model 1) has three degrees of freedom per node while the second model
(model 2) is scalar (one degree of freedom). We are trying several
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