The TSAdaptSetType is being called. Looking at TSStep_Theta, is it
possible that here:
/* Register only the current method as a candidate because we're not
supporting multiple candidates yet. */
ierr = TSGetAdapt(ts,&adapt);CHKERRQ(ierr);
ierr = TSAdaptCandidatesClear(adapt);CHKERRQ(ierr);
ierr =
TSAdaptCandidateAdd(adapt,NULL,th->order,1,th->ccfl,1.0,PETSC_TRUE);CHKERRQ(ierr);
ierr =
TSAdaptChoose(adapt,ts,ts->time_step,&next_scheme,&next_time_step,&accept);CHKERRQ(ierr);
TSAdaptCandidatesClear is unsetting whatever method I'm setting?
On 04/24/2015 06:41 PM, Barry Smith wrote:
On Apr 24, 2015, at 4:08 PM, Mark Lohry <[email protected]> wrote:
I'm new to PETSc and not sure how to go about debugging. Running with
-start_in_debugger runs in gdb with the normal output (where would i put a
breakpoint for this?)
You could start by putting a break point in TSAdaptSetType() and see if your call is
made and then if any call is made after that by other code changing it to something else.
You could put a breakpoint in TSStep_Theta (which supports beuler) and "next"
through that to see why it is using an adapter that actually does something.
Barry
and running with -info dumps a lot of information but only related to SNES and
KSP, nothing about time stepping or adapt.
On 04/24/2015 04:29 PM, Barry Smith wrote:
Run in the debugger (with one process obviously) to see why it is still
calling an adaptor.
Barry
On Apr 24, 2015, at 3:16 PM, Mark Lohry <[email protected]> wrote:
Trying a simple stiff test case (y'=y^2*(1-y)) using TSBEULER, to get a feel
for implicit stepping with JFNK.
I'm giving it a pretty large timestep, and the default appears to start
adapting the time step around the stiff part of the solution. So I tried
turning it off:
TSAdapt adapt;
TSGetAdapt(its,&adapt);
TSAdaptSetType(adapt,TSADAPTNONE);
and even fixing the limits:
TSAdaptSetStepLimits(adapt,40.0,40.0);
And it still ignores it and adapts anyway. At t=800 (where the solution gets
very stiff, so one would normally see adaptive stepping there if it was
desired) it's dropping dt from 40 to 10.
Printing (t,y) here from the ts monitor:
600.000000,0.002790;
640.000000,0.003198;
680.000000,0.003761;
720.000000,0.004606;
760.000000,0.006072;
800.000000,0.010155;
810.000000,0.011452;
820.000000,0.013161;
830.000000,0.015538;
840.000000,0.019126;
850.000000,0.025426;
860.000000,0.043639;
900.000000,0.975519;
940.000000,0.999402;
980.000000,0.999985;
1020.000000,1.000000;
1060.000000,1.000000;
1100.000000,1.000000;
1140.000000,1.000000;
1180.000000,1.000000;
Any idea? Adaptive stepping is great, but I'd still like to be able to fix the
time step.
