On 3/23/15 5:34 PM, Jed Brown wrote:
Lisandro Dalcin <dalc...@gmail.com> writes:
On 21 March 2015 at 17:32, Emil Constantinescu <emcon...@mcs.anl.gov> wrote:
When -ts_theta_adapt is used, then it detects the instability as an error
and reduces the step by a lot! wlte=1.24e+03 which means that the reduction
should be severe but the controller tries 0.1*dt and that seems to pass but
it "jig-saws" (take a look at the next attempted step), which means that it
is likely unstable.
I think -ts_theta_adapt is seriously broken, I cannot make sense of
the way the error estimator is computed.
This was Shri's implementation. TSEvaluateStep_Theta looks wrong to me,
both using U as an input and assuming that Xdot is set. I don't even
know what the intended math is for a first-order embedded estimate in
midpoint (theta=0.5).
I was off for the last few days and I wasn't able to follow the call
sequence - I had assumed it was correct. I'll take Debo and look into it.
Emil
