Thank you?I know that you are trying to let me know to match the vector element
with the matrix.But it seems, the total number of rows (suppose m) has to
satisfy??? m = N * r,where N is the number of process and r is the local
range.Am I right?
--- 09?11?30????, Barry Smith <bsmith at mcs.anl.gov> ???
???: Barry Smith <bsmith at mcs.anl.gov>
??: Re: How to fill a matrix with a vector parallelly
???: "PETSc users list" <petsc-users at mcs.anl.gov>
??: 2009?11?30?,??,??11:33
On Nov 29, 2009, at 9:21 PM, ming zhu wrote:
> OK.
> may I ask , I think Petsc matrix is row -based. That means,
> MatGetArray(Mat mat,PetscScalar *v[])
> v[0] is the pointer to the first row. v[0][0] is the value of mat[0][0].
> Am I right?
???No. It is column based and there is just one array for the who thing so
v[0:m-1] is the first column v[m:2m-1] is the next column etc
> And do you mean that, each time I got a vector, I create a sub matrix to
> store it.
No. Just create the full matrix and copy over each vector as you get it.
? Barry
> Later on, the merging will be a problem.
>
> --- 09?11?30????, Barry Smith <bsmith at mcs.anl.gov> ???
>
> ???: Barry Smith <bsmith at mcs.anl.gov>
> ??: Re: How to fill a matrix with a vector parallelly
> ???: "PETSc users list" <petsc-users at mcs.anl.gov>
> ??: 2009?11?30?,??,??11:12
>
>
> On Nov 29, 2009, at 9:09 PM, ming zhu wrote:
>
> > Thank you for your quick reply.
> > Two questions:
> > one,? ???how do I know which part belongs to the present processor?
>
>???Call VecGetOwnershipRange() to know what rows of the vector belong to the
>process. Then create the MPIDense matrix with the same number of local rows.
>
> > second, is there any examples for this kind of question?
> >
> > Thank you
> >
> > --- 09?11?30????, Barry Smith <bsmith at mcs.anl.gov> ???
> >
> > ???: Barry Smith <bsmith at mcs.anl.gov>
> > ??: Re: How to fill a matrix with a vector parallelly
> > ???: "PETSc users list" <petsc-users at mcs.anl.gov>
> > ??: 2009?11?30?,??,??9:53
> >
> >
> >???Since evenvectors will (almost always) be dense vectors you will want to
> >use a MPIDENSE matrix to store them. So create a MPIDENSE matrix with the
> >same row layout as the eigenvector then on each process use VecGetArray() to
> >access that processes part of the vector and MatGetArray() to access that
> >part of the matrix and copy the values over from the vector array to the
> >matrix array.
> >
> >? ? Barry
> >
> > On Nov 29, 2009, at 7:41 PM, ming zhu wrote:
> >
> > > HI
> > > I am trying to solve an eigenvalue problem. A = U * LAMBDA*U'.? While
> > > SLEPC proivdes a solver to get an eigenvector and the related eigenvalue,
> > > I have to fill the eigenvector to form the eigen matrix. However, there
> > > seems no such function to do this directly. I was trying to use
> > > VecGetValues and filled the matrix one by one. Howevevr, it can not do
> > > that in parallel.
> > >
> > >? ? Is there anyone can help me ?
> > >
> > > Thank you
> > >
> > >
> > > ?????????????????
> >
> >
> > ?????????????????
>
>
> ?????????????????
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