Re: [SOSlib-discuss] starting a solver at an arbitrary time

[Rainer M. <ra...@tb...>]

Hi Eric,

 > I would like to start a solver at an arbitrary time instead of time=0,

I fear that this is not easily possible. The main reason is that it 
would violate SBML definitions, where the initial conditions always 
correspond to an initial time 0 (imagine non-autonomous systems which 
explicitly have "time" on the right-hand-side of the ODE system, or 
time-dependent events etc.).

What you could do is integrate to this starting time point and then

a) set all values to the initial conditions via 
IntegratorInstance_setVariableValue
or
b) via IntegratorInstance_copyVariableState from a fresh integrator 
instance of the same model and which has not been integrated yet.

If you want to use option b please let me know. The function needs to be 
adapted for this case, because currently it can only be used without 
prior integration of the target integrator.

However, both options involve unnecessary integrations to your start 
time, and i would recommend handling the time differences externally, 
i.e. remember the different time for this integrator and add it for your 
output yourself.
Would this latter option be OK for you?

I am not sure currently what the implications (in coding hours, maybe 
its only minutes but i dont know ;) ) would be to implement arbitrary 
start times - in principle it would however be possible.

Rainer





Eric Fernandez wrote:
> Hi,
> 
> I would like to start a solver at an arbitrary time instead of time=0,
> using the same initial conditions (and then continue until
> IntegratorInstance_timeCourseCompleted(engine) is false, aka reaches the
> simulation time).
> That would be only a time translation, but could be handy for designing
> cell populations. Is that possible, even after the CVOdeSettings have
> been set (eg using the same IntegratorInstance, resetting it after a
> first solving, and restarting from a later time but with the initial
> conditions).
> 
> Thanks for your advice,
> Eric Fernandez
> 
> 
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