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. > > >
