On Sat, Oct 21, 2017 at 2:20 AM, Jose E. Roman <[email protected]> wrote:
> This was added in 3.8 to check the common case when people incorrectly > sets shift-and-invert with EPS_SMALLEST_MAGNITUDE. To compute smallest > eigenvalues with shift-and-invert the correct way is to set target=0 and > which=EPS_TARGET_MAGNITUDE. See for instance > http://slepc.upv.es/documentation/current/src/eps/ > examples/tutorials/ex13.c.html Jose, one thing we are trying to do in PETSc now is to give the options to fix a problem (or at least representative options) directly in the error message. Or maybe a pointer to the relevant manual or tutorial section. This gives users a hand up. Thanks, Matt > > Jose > > > > El 21 oct 2017, a las 1:51, Matthew Knepley <[email protected]> > escribió: > > > > On Fri, Oct 20, 2017 at 7:43 PM, Kong, Fande <[email protected]> wrote: > > Hi All, > > > > I am trying to solve a generalized eigenvalue problem (using SLEPc) with > "-eps_type krylovschur -st_type sinvert". I got an error message: "Must > select a target sorting criterion if using shift-and-invert". > > > > Not sure how to proceed. I do not quite understand this sentence. > > > > You need to know how to choose the shift. So for instance you want the > smallest eigenvalues, or the closest to zero, etc. > > I don't know the options, but they are in the manual. > > > > Matt > > > > > > Fande, > > > > > > > > -- > > 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 > > > > https://www.cse.buffalo.edu/~knepley/ > > -- 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 https://www.cse.buffalo.edu/~knepley/ <http://www.caam.rice.edu/~mk51/>
