Hi,
how do you use composite preconditioners in petsc4py. I used to have a
script that worked but it does not work anymore. Something has changed. Any
simple examples?
Regards,
Adolfo
The matrix can be a shell matrix, only the matrix-vector product operation is
required.
Jose
> El 30 ene 2023, a las 22:23, Guglielmo, Tyler Hardy via petsc-users
> escribió:
>
> I have an implementation of the slepc MFN matrix exponential which is
> implicitly using ExpoKit. You have to
I have an implementation of the slepc MFN matrix exponential which is
implicitly using ExpoKit. You have to supply a matrix into the Slepc MFN
operator to set the problem up as far as I know.
Tyler
From: Matthew Knepley
Date: Monday, January 30, 2023 at 12:24 PM
To: Guglielmo, Tyler Hardy
On Mon, Jan 30, 2023 at 3:08 PM Guglielmo, Tyler Hardy via petsc-users <
petsc-users@mcs.anl.gov> wrote:
> I would need the Kronecker product to be explicitly available to perform
> matrix exponentials. A and B are of order 5000, so not too large. I will
> give storing them on all ranks a shot.
I would need the Kronecker product to be explicitly available to perform matrix
exponentials. A and B are of order 5000, so not too large. I will give
storing them on all ranks a shot. Thanks for the tips!
Best,
Tyler
From: Barry Smith
Date: Monday, January 30, 2023 at 12:01 PM
To:
What is large? If A and B have dimensions of 1000, then the Kronecker product
is of size 1,000,000. Do you want the Kronecker product to be explicitly formed
or just available as matrix vector products? If just explicitly available then
I think you can just store sparse A (for example)
Both matrices (A and B) would be approximately the same size and large. The
use case (for me at least) is to create several large sparse matrices which
will be combined in various ways through Kronecker products. The combination
happens at every time step in an evolution, so it really needs
On Mon, Jan 30, 2023 at 2:24 PM Guglielmo, Tyler Hardy via petsc-users <
petsc-users@mcs.anl.gov> wrote:
> Thanks Barry,
>
>
>
> I saw that function, but wasn’t sure how to apply it since the
> documentation says that S and T are dense matrices, but in my case all
> matrices involved are sparse.
Thanks Barry,
I saw that function, but wasn’t sure how to apply it since the documentation
says that S and T are dense matrices, but in my case all matrices involved are
sparse. Is there a way to work around the dense requirement?
Best,
Tyler
From: Barry Smith
Date: Monday, January 30, 2023
Do you need the explicit sparse representation of the Kronecker product? Or
do you want to apply it as an operator or solve systems with it? If the latter
you can use
https://petsc.org/release/docs/manualpages/Mat/MatCreateKAIJ/#matcreatekaij
Barry
> On Jan 30, 2023, at 12:53 PM,
Hi all,
I am wondering if there is any functionality for taking Kronecker products of
large sparse matrices that are parallel? MatSeqAIJKron is as close as I have
found, but it seems like this does not work for parallel matrices. Any ideas
here?
An option could be to make A and B
VecGetOwnershipRange() works with any vector, including DM created vectors.
You could not have the global ownership you provide below.
Perhaps you are thinking about the Natural ownership values? For those if you
using DMDA take a look at DMDAGetAO() and DMDACreateNaturalVector()
Barry
Hello,
I am using a DMCreateGlobalVector to create a vector V. If V is divided into m
processes, is there a way to get the global indices of V assigned to each
process?
For example: V = [10, 20, 30, 40, 50, 60, 70, 80].
If MPI process 0 has [10, 40, 50, 60] and process 1 has [20, 30, 70, 80],
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