> On Jun 2, 2015, at 3:29 PM, Dmitry Karpeyev <[email protected]> wrote: > > Currently -pc_type lu will not detect a zero pivot (it will happily produce > an Inf or a NaN) and the flag it checks whether to see whether > to do it is erroriffpe. KSP_DIVERGED_NANORINF is too generic. What if the > user wants to verify there is a zero pivot?
-ksp_error_if_not_converged will cause an immediate stack trace when the zero pivot occurs (as would the user calling MatSetErrorIfFPE() on the matrix or the use of -mat_error_if_fpe if it existed). There is no way currently to get back programatically anything more specific than KSP_DIVERGED_NANORINF on a zero pivot, we can start adding more that has nothing to do with -mat_error_if_fpe > > Also, irrespective of the use case, if we have a XXXSetYYY(), isn't our > policy to have a command-line way of doing it? No, only when it makes sense and doesn't duplicate other functionality. I don't see -mat_error_if_fpe in this case adding anything more helpful then the already existing -ksp_error_if_not_converged Convince me. Barry > > On Tue, Jun 2, 2015 at 2:21 PM Barry Smith <[email protected]> wrote: > > > On Jun 2, 2015, at 3:02 PM, Dmitry Karpeyev <[email protected]> wrote: > > > > Should we have a way to turn on/off MatErrorIfFPE() on the command line? > > Sure, one does it with -ksp_error_if_not_converged or > -snes_error_if_not_converged It only adds to user confusion, but no user > benefit, to have a -mat_error_if_fpe thing. > > What user case do think there is for a -mat_error_if_fpe ? > > Barry > > > > > It is now turned off by default to allow Inf/NaNs to propagate and > > currently the only way to toggle it is programmatic. > > > > > > Dmitry. >
