[petsc-users] Getting access to matrix rows without and setting values simultaneously

[Jed Brown]

On Thu, Jun 16, 2011 at 17:57, Matthew Knepley <knepley at gmail.com> wrote:
>
>
> Doesn't he need A' A (normal equations)
>

Note that A has many more columns than rows, therefore A'*A has huge null
space.


> for the solve, so a MatShell?
>

I'm sorry, yes. Or MatComposite:

http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-dev/docs/manualpages/Mat/MatCreateComposite.html

But there is also likely some regularization so MatShell makes sense.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20110616/8e379643/attachment.htm>