The value -eps_ncv 5000 is huge. Better let SLEPc use the default value. Jose
> El 10 jun 2022, a las 14:24, Jin Runfeng <[email protected]> escribió: > > Hello! > I want to acquire the 3 smallest eigenvalue, and attachment is the log view > output. I can see epssolve really cost the major time. But I can not see why > it cost so much time. Can you see something from it? > > Thank you ! > > Runfeng Jin > > On 6月 4 2022, at 1:37 凌晨, Jose E. Roman <[email protected]> wrote: > Convergence depends on distribution of eigenvalues you want to compute. On > the other hand, the cost also depends on the time it takes to build the > preconditioner. Use -log_view to see the cost of the different steps of the > computation. > > Jose > > > > El 3 jun 2022, a las 18:50, jsfaraway <[email protected]> escribió: > > > > hello! > > > > I am trying to use epsgd compute matrix's one smallest eigenvalue. And I > > find a strang thing. There are two matrix A(900000*900000) and > > B(90000*90000). While solve A use 371 iterations and only 30.83s, solve B > > use 22 iterations and 38885s! What could be the reason for this? Or what > > can I do to find the reason? > > > > I use" -eps_type gd -eps_ncv 300 -eps_nev 3 -eps_smallest_real ". > > And there is one difference I can tell is matrix B has many small value, > > whose absolute value is less than 10-6. Could this be the reason? > > > > Thank you! > > > > Runfeng Jin > <log_view.txt>
