[Trilinos-Users] LSQR preconditioner

[Hoemmen, Mark]

On 9/30/14, 12:00 PM, "trilinos-users-request at software.sandia.gov"
<trilinos-users-request at software.sandia.gov> wrote:
>Message: 2
>Date: Tue, 30 Sep 2014 12:11:41 +0200 (CEST)
>From: Antonella Longo <longo at pi.ingv.it>
>To: trilinos-users at software.sandia.gov
>Cc: Deepak Garg <deepak.garg at pi.ingv.it>
>Subject: [Trilinos-Users] LSQR preconditioner
>Message-ID:
>	<510420223.2904028.1412071901088.JavaMail.root at email.pi.ingv.it>
>Content-Type: text/plain; charset=utf-8
>
>We would like to solve a non-square system of equations
>with the LSQR solver of Trilinos-11.2.5.
>Is there any preconditioner for LSQR non-square system
>solver in Trilinos?

You may use any preconditioner you like.  Setting the preconditioner works
just like any other Belos solver.  However, do note that preconditioning
may change the solution of the least-squares problem.  In the case of
LSQR, it changes the regularization matrix, which without preconditioning
is just the identity.  Setting a preconditioner amounts to defining a norm
that "smoothes" the solution.  As far as I know, Trilinos does not
implement preconditioners specifically for nonsquare least-squares
problems.

mfh