Hi Ellen, It is as Alp said. To emphasize what he said, you don't need to worry about using a bounded CG method - the bounded CG methods can be used for unconstrained problems, and are much better than the old unconstrained CG code.
On Thu, Feb 27, 2020, 9:55 AM Dener, Alp via petsc-users < petsc-users@mcs.anl.gov> wrote: > Hi Ellen, > > It looks like you’re using the old unconstrained CG code. This will be > deprecated in the near future in favor of the newer bound-constrained CG > algorithm (TAOBNCG) that can also solve unconstrained problems when the > user does not specify any bounds on the problem. > > The newer TAOBNCG algorithm implements a preconditioner that significantly > improves the scaling of the search direction and helps the line search > accept the unit step length most of the time. I would recommend making sure > that you’re on PETSc version 3.11 or newer, and then switching to this with > “-tao_type bncg”. You will not need to change any of your code to do this. > If you still fail to converge, please send a new log with the new algorithm > and we can evaluate the next steps. > > — > Alp Dener > Postdoctoral Researcher > Argonne National Laboratory > https://www.anl.gov/profile/alp-dener > > On February 26, 2020 at 6:01:34 PM, Ellen Price ( > ellen.pr...@cfa.harvard.edu) wrote: > > Hi Jed, > > Thanks for getting back to me! Here's the output for my CG config. Sorry > it's kind of a lot. > > Ellen > > On Wed, Feb 26, 2020 at 12:43 PM Jed Brown <j...@jedbrown.org> wrote: > >> Could you share output for your current configuration with -tao_monitor >> -tao_ls_monitor -tao_view? >> >> "Ellen M. Price" <ellen.pr...@cfa.harvard.edu> writes: >> >> > Hello PETSc users! >> > >> > I am using Tao for an unconstrained minimization problem. I have found >> > that CG works better than the other types for this application. After >> > about 85 iterations, I get an error about line search failure. I'm not >> > clear on what this means, or how I could mitigate the problem, and >> > neither the manual nor FAQ give any guidance. Can anyone suggest things >> > I could try to help the method converge? I have function and gradient >> > info, but no Hessian. >> > >> > Thanks, >> > Ellen Price >> >