On Tue, Dec 2, 2008 at 7:52 PM, Chris Cooper <chrisc at al.com.au> wrote:
> Hi, > > Just wondering if there are any techniques for improving DMMG convergence > on a linear problem when operating in single precision? > > eg using ksp example 34 in Petsc 2.3.3 with multigrid levels changed to > 6... > > double precision: > 0 KSP Residual norm 4.451733404502e-02 > 1 KSP Residual norm 2.801676364873e-04 > 2 KSP Residual norm 3.215426166316e-06 > 3 KSP Residual norm 5.446277176355e-08 > Residual norm 5.44628e-08 > Error norm 0.000356798 > Error norm 9.21724e-05 > Error norm 1.34208e-07 > > single precision: > 0 KSP Residual norm 4.450287297368e-02 > 1 KSP Residual norm 2.799208450597e-04 > 2 KSP Residual norm 2.232483529951e-05 > 3 KSP Residual norm 1.575733222126e-05 > 4 KSP Residual norm 1.286925271415e-05 > ... > 27 KSP Residual norm 4.369261660031e-06 > 28 KSP Residual norm 4.287577212381e-06 > 29 KSP Residual norm 4.210308816255e-06 > 30 KSP Residual norm 2.235170904896e-05 > 31 KSP Residual norm 1.709007477757e-07 This bothers me. Shouldn't the Residual norm be the same as the last residual, as it is above? Matt Residual norm 8.45584e-07 > Error norm 0.000370784 > Error norm 9.54664e-05 > Error norm 1.38935e-07 > > thanks, > Chris Cooper > Animal Logic > > Animal Logic > http://www.animallogic.com > > Please think of the environment before printing this email. > > This email and any attachments may be confidential and/or privileged. If > you are not the intended recipient of this email, you must not disclose or > use the information contained in it. Please notify the sender immediately > and delete this document if you have received it in error. We do not > guarantee this email is error or virus free. > > > > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20081202/42c978ad/attachment.htm>
