[petsc-users] Extracting data from a Petsc matrix

[Matthew Knepley]

On Wed, Aug 14, 2013 at 12:17 PM, Harshad Sahasrabudhe
<hsahasra at purdue.edu>wrote:

> Thanks Barry.
>
> How do we get the compiler names from the Python build system? For
> example, MAGMA make.inc varies depending on whether the compiler is gcc or
> icc. So is there any easy way to get this information?
>

That is a horrible way to organize a build. Just ignore what they are doing
with flags and use the PETSc flags. Take
a look at Chaco.py for a simple install.

   Matt


> Harshad
>
> ----- Original Message -----
> From: "Barry Smith" <bsmith at mcs.anl.gov>
> To: "Harshad Sahasrabudhe" <hsahasra at purdue.edu>
> Cc: "Jed Brown" <jedbrown at mcs.anl.gov>, petsc-users at mcs.anl.gov
> Sent: Monday, August 12, 2013 5:25:53 PM
> Subject: Re: [petsc-users] Extracting data from a Petsc matrix
>
>
> On Aug 12, 2013, at 4:05 PM, Harshad Sahasrabudhe <hsahasra at purdue.edu>
> wrote:
>
> > Hi Jed,
> >
> > I am now working to add library support for LU decomposition using
> MAGMA. I need your help with the following:
> >
> > 1) How do I add the options --download-magma, --with-magma, etc. to the
> configure script for building with MAGMA?
>
>    Add a new file in config/PETSc/packages  (copy one that is already
> there and modify for magma).
> >
> > 2) I have a fair idea how the PETSc code is structured and how to add
> source code to the impls/ directory. How does PETSc get to know that there
> is an additional implementation (in this case MAGMA) in this directory? Is
> there a config file of some sort?
>
>     Add the new directory name to list of directories in the makefile in
> that directory and add in MatRegisterAll().
>
>    Barry
>
> >
> > Thanks,
> > Harshad
> >
> > ----- Original Message -----
> > From: "Jed Brown" <jedbrown at mcs.anl.gov>
> > To: hsahasra at purdue.edu, petsc-users at mcs.anl.gov
> > Sent: Saturday, July 13, 2013 12:43:08 PM
> > Subject: Re: [petsc-users] Extracting data from a Petsc matrix
> >
> > "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
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