At 2013-01-16 03:02:32,"Barry Smith" <bsmith at mcs.anl.gov> wrote: > >> 1.701448294063e+04 > 1.e4*1.145582415879e+00 hence it declares divergence
Hello, Barry I made some tests and it is true. Thanks. But in the mannual, both version 3.2 and 3.3, the rule is:||rk||>dtol*||b||. It is ||b||, not r_0. My misunderstanding? Or the error in the mannual? Besides, in the mannual, both version 3.2 and 3.3, the default dtol=1.0E+5. But from the results in the example, it is 1.0E+4. I donot know the reason. My petsc version is 3.2-p7. Thanks. Jim >Note that at iteration 171 the preconditioned residual is 9.348832909193e-13 < >1.e-12 * 1.145582415879e+00 very good convergence. > >You seem to have set an unreasonably tight convergence criteria. In double >precision you can never realistically expect to use a rtol smaller than e-12. >In fact normally it is not reasonable to use more than like 1.e-8. Those extra >digits don't mean anything. > > Barry > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20130116/0d4c947d/attachment.html>
