Hi Francois,

> I am trying to benchmark ViennaCL against the MKL for GMRES
> preconditioned by ILU0 factorization. It turns out that I get different
> number of iterations for both solvers. Where can I get more information
> about the convergence criteria?
>
> More precisely, if we are trying to solve A.x = y, preconditioned by B
> (so we try to solve B.A.x = B.y If I understand correctly), with a
> relative error of epsilon, what is the convergence criteria ?
> - Is it Norm(A.x_n - y) <= epsilon Norm(y) ?
> - Which norm is used ?
> - Can we customize the norm used?

The convergence criterion is monitoring the relative preconditioned 
2-norm, i.e.
  ||BAx - By|| // ||By||
You can customize the termination criterion by passing a suitable 
monitor routine, but you cannot modify the norm used for monitoring 
convergence.

Best regards,
Karli


>
> Best regards,
>
> François Fayard
> Founder & Consultant - Inside Loop
> Tel: +33 (0)6 01 44 06 93
> Web: www.insideloop.io <http://www.insideloop.io>
>
>
>
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