[petsc-users] How to call a lapack routine in the petsc?

[Fande Kong]

Thanks,

Got it.


On Thu, Dec 11, 2014 at 9:09 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>
> > On Dec 11, 2014, at 9:54 PM, Fande Kong <fdkong.jd at gmail.com> wrote:
> >
> > Hi Barry,
> >
> > Thanks.
> >
> > I know how to solve a dense linear system in the petsc, but I was
> wondering how to call a Lapack routine in the petsc.
>
>    You asked how to call a lapack routine to solve a dense linear system.
> That is exactly what I told you. For seqdense matrices PETSc lu solvers
> directly call the LAPACK routines to do the factorization and the solves.
>
>    Sure it is possible to call LAPACK routines directly to solve a
> sequential dense linear system but there is no reason to do that since
> PETSc does it for you. For dense matrices of dimension 10 or larger the
> overhead of calling through PETSc is negligible so there is no good reason
> to call lapack directly.
>
>   Barry
>
> >
> >
> >
> > On Thu, Dec 11, 2014 at 8:47 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> > > On Dec 11, 2014, at 9:33 PM, Fande Kong <fdkong.jd at gmail.com> wrote:
> > >
> > > Hi all,
> > >
> > > How to call a Lapack routine to solve a dense linear system? Any
> simple example?
> >
> >    Create the Mat with MatCreateSeqDense() then create the usual KSP and
> use for the solver options -pc_type lu -ksp_type preonly
> >
> >     See src/ksp/ksp/examples/tutorials/ex30.c
> >
> >
> >    Barry
> >
> > >
> > > Thanks,
> > >
> >
>
>
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