[petsc-users] Factor Matrix

[Barry Smith]

On Mar 2, 2011, at 6:52 PM, Joshua Booth wrote:

> In reply,
> 
> Yes , I meant with MatCopy or MatConvert.
> 
> I need the values so I can store them in a larger matrix for latter use.  It is in process of working on an experimental multilevel method.

   Store the LU factors or C factors of a given matrix inside a larger matrix. Strange stuff. This is exactly the case where you should include src/mat/impls/sbaij/seq/sbaij.h
and access the data structure directly to do what you want with the values.

  Barry

> 
> Josh
> 
> 
> On Wed, Mar 2, 2011 at 7:36 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> 
> On Mar 2, 2011, at 6:12 PM, Joshua Booth wrote:
> 
> > In petsc, I am able to get a cholesky factor matrix from MatCholeskyFactor, but I am unable to copy
> 
>   Do you mean MatCopy() ?
> 
> > or get values from it after.
> 
>   What do you want to use the values for? Normally they are only used in triangular solvers with MatSolve().
> 
>   The data is stored in a matrix specific format. You would have to include the private include files and access the data directly if you need it. src/mat/impls/sbaij/seq/sbaij.h
> 
> 
>   Barry
> 
> > Why is this?  Is there a work around?
> >
> > Joshua Booth
> 
>