[R-sig-dyn-mod] Hybrid simulation of nonlinear ode and discrete state machine
Eike Petersen
eike.petersen at uni-luebeck.de
Mon Dec 12 17:25:37 CET 2016
Maybe I'm mistaken, but I think you misunderstood me: I'm really dealing
with a nonlinear function of the first derivative of the state on my
left-hand side. By
y'^2 + y'
I really mean the squared of the first derivative, plus the same
derivative itself. I am *not* talking about a second derivative here. I
stand to be corrected, but as far as I know, there are no general
techniques to transform (fully implicit?) ODEs of this type into a
system of linear first-order ODEs.
Hence I am currently using the daspk solver for my problem, since it can
deal with fully implicit ODEs. However, returning to my initial
question, I'd like to use the output of a finite state machine (FSM) as
the input function to my problem. This requires the efficient and
reliable detection of state transitions, for which I wanted to use the
'root function' solver option. According to the deSolve documentation
however, this option is currently not implemented for the daspk solver,
which is why I wrote to this list, asking for my options.
Hopefully this clarifies things a bit.
Kind regards and thanks for your time,
Eike
On 12/09/2016 11:59 PM, Thomas Petzoldt wrote:
> Thanks for clarification. The transformation of a second order
> derivative is briefly shown here:
>
> https://journal.r-project.org/archive/2010-2/RJournal_2010-2_Soetaert~et~al.pdf#3
>
>
> and some more may be found in the book of Soetaert, Cash and Mazzia:
>
> http://www.springer.com/cn/book/9783642280696
>
>
> Thomas
>
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