Hi Jed, in general, I am using only RTOL with ATOL=0, sometimes (if the range of the physical solution is known a priori) I use both criteria. Actually, Matthew already helped me to build my own KSPConverged routine including the minimum iteration number.
Thanks a lot for all your effort and great support, Rolf Am 28.07.2014 um 17:37 schrieb Jed Brown: > Rolf Kuiper <[email protected]> writes: >> I need this to e.g. solve a linear system of equations several times >> (as the physical system proceeds in time); during a single call / >> timestep, the system, might not change stronger than the RTOL in use, >> but in the long-run (several hundreds to thousands of calls), the >> system will actually change by several RTOL; nonetheless, the default >> KSP solver stops without doing any iteration (= 0), i.e. the system >> does not change at all. > > When you use -ksp_converged_reason, is it completing due to RTOL or > ATOL? For transient problems, it's often good to set an absolute > tolerance.
