Hi All, I have a question about -ksp_rtol. when I run my application with -ksp_rtol 1e-2, I got the convergence history as the follows.
0 KSP preconditioned resid norm 2.129970351489e+03 true resid norm 1.040507012955e-02 ||Ae||/||Ax|| 1.000000000000e+00 1 KSP preconditioned resid norm 3.979448548799e+01 true resid norm 7.588481061015e-03 ||Ae||/||Ax|| 7.293060946766e-01 2 KSP preconditioned resid norm 2.177668520277e+01 true resid norm 6.608917234932e-03 ||Ae||/||Ax|| 6.351631610983e-01 3 KSP preconditioned resid norm 2.519310038389e+00 true resid norm 4.725744786785e-03 ||Ae||/||Ax|| 4.541771201874e-01 KSP Object: type: gmres ... when I run my application with -ksp_rtol 1e-3, I got the convergence history as the follows. 0 KSP preconditioned resid norm 2.129970351489e+03 true resid norm 1.040507012955e-02 ||Ae||/||Ax|| 1.000000000000e+00 1 KSP preconditioned resid norm 3.979448548799e+01 true resid norm 7.588481061015e-03 ||Ae||/||Ax|| 7.293060946766e-01 2 KSP preconditioned resid norm 2.177668520277e+01 true resid norm 6.608917234932e-03 ||Ae||/||Ax|| 6.351631610983e-01 3 KSP preconditioned resid norm 2.519310038389e+00 true resid norm 4.725744786785e-03 ||Ae||/||Ax|| 4.541771201874e-01 4 KSP preconditioned resid norm 5.945684204702e-01 true resid norm 2.622092992533e-03 ||Ae||/||Ax|| 2.520014723483e-01 KSP Object: type: gmres How can I explain the relative tolerance is function correctly? as you can see from the term ||Ae||/||Ax||, neither of my testruns seems to stop at the right place(should be 10^(-2), 10^(-3) respectively). Thanks a lot. Yan -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20090915/268d348b/attachment.htm>
