[petsc-users] Extracting data from a Petsc matrix

[Barry Smith]

   Read all of http://www.mcs.anl.gov/petsc/developers/index.html

    Note that if Magma has a calling sequence like lapack you could possible steal chunks of code from the routines I pointed you to yesterday and modify them as needed so you don't need to reinvent the wheel.


   Barry

On Jul 16, 2013, at 1:37 PM, Matthew Knepley <knepley at gmail.com> wrote:

> On Tue, Jul 16, 2013 at 1:13 PM, Harshad Sahasrabudhe <hsahasra at purdue.edu> wrote:
> Hi Jed,
> 
> Thanks for your reply.
> 
> You're on your own for storage of factors.  Alternatively, you could add
> library support so that you could use PCLU and
> '-pc_factor_mat_solver_package magma' (or PCFactorSetMatSolverPackage).
> Doing this is not a priority for us, but we can provide guidance if you
> want to tackle it.
> 
> I would definitely like to start working on adding library support. I think this is the most efficient way to go about it. Can you give me certain details such as:
> 
> 1) How should I start going about it?
> 
> Read the UMFPACK implementation
>  
> 2) How will I check-in the changes to Petsc?
> 
> Using Git
>  
> 3) What version of Petsc will the changes be reflected in if I started working on it right now?
> 
> A branch of 'master'
>  
> 4) How many hours does it generally take to get this done?
> 
> How many licks does it take to get to the center of a Tootsie Roll Pop?
>  
> 5) How is the peer review done?
> 
> Through a pull request on BitBucket.
> 
>   Thanks,
> 
>      Matt
>  
> Thanks,
> Harshad
> 
> On 07/13/2013 12:43 PM, Jed Brown wrote:
> "hsahasra at purdue.edu" <hsahasra at purdue.edu> writes:
> 
> Hi,
> 
> I am working on solving a system of linear equations with square
> matrix. I'm first factoring the matrix using LU decomposition.
> I assume you're solving a dense problem because that is all MAGMA does.
> 
> I want to do the LU decomposition step using MAGMA on GPUs. MAGMA
> library implements LAPACK functions on a CPU+GPU based system.
> 
> So my question is, how do I extract the data from a Petsc Mat so that
> it can be sent to the dgetrf routine in MAGMA.
> MatDenseGetArray
> 
> Is there any need for duplicating the data for this step?
> You're on your own for storage of factors.  Alternatively, you could add
> library support so that you could use PCLU and
> '-pc_factor_mat_solver_package magma' (or PCFactorSetMatSolverPackage).
> Doing this is not a priority for us, but we can provide guidance if you
> want to tackle it.
> 
> 
> 
> 
> -- 
> What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead.
> -- Norbert Wiener