On Wed, Mar 21, 2012 at 04:03, Alexander Grayver <agrayver at gfz-potsdam.de>wrote:
> Hello, > > Plotting values of relative residual norm versus iteration I noticed that > these curves have different behavior. For instance, ones I got with > BiCGStab are oscillatory and rather noisy with large jumps within few > iterations. Curves for QMR are smooth, however it's usual that they > stagnate for ~10-20 iterations and then go down further. Same > preconditioner is applied for both and both methods are Lanczos based, so I > don't understand this. > I'm wondering is this just my specific case or there is general > explanation for that? > This is normal. http://people.maths.ox.ac.uk/trefethen/publication/PDF/1992_52.pdf -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20120321/eb1dddf9/attachment.htm>
