Catherine Lloyd wrote:
However, we now face a different problem... Although we can easily
describe the switches as piece-wise equations, if we define a single
variable more than once in a CellML model the simulation tools tell us
that the model is over constrained.
For example in this case we already have a differential equation
describing the change in mass over time, and then we have a second
equation placing a condition on mass:
No, no. Events are not assignment rules. In SBML as well, you could not
have a rate rule and an assignment rule on mass. Events are discontinuous
processes taking place in between simulation iterations. I think this is
just a missing concept in CellML. It exists in simulators like XPP and
GENESIS, used for neuronal simulations (e.g. to reset voltage in spiking
neurons).
(To be absolutely frank, the existence of events as part of the core SBML
has been challenged many times. But I think we can now see why they are
needed :-))
--
Nicolas LE NOVERE, Computational Neurobiology, EMBL-EBI, Wellcome-Trust
Genome Campus, Hinxton CB101SD UK, Mob:+447833147074, Tel:+441223494521
Fax:468, Skype:n.lenovere, AIM:nlenovere, MSN:[email protected]
http://www.ebi.ac.uk/~lenov/, http://www.ebi.ac.uk/compneur/
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