[SciPy-user] integrate.odeint , stiff chemical equations and mass conservation -any hint?

ms devicerandom@gmail....
Tue Jun 2 13:47:32 CDT 2009

Hi Anne,

Thanks for the suggestions! I didn't know about pydstool and I will
definitely try it.

> On the other hand, it may be more valuable to keep the total mass as a
> free parameter so that you can judge the quality of your solutions by
> looking at how much it varies. After all, the total mass is only one
> direction in which your approximate solution can deviate from the true
> solution.

True; however we want to use the model to predict somehow the
concentrations of species in a chemical system, and if mass is not
conserved (it goes up like 10 times) such prediction won't look good :)

> It's also, of course, possible there's a bug in your derivative
> function - it's worth checking that the derivative vector is always
> orthogonal to the gradient of mass-as-a-function-of-your-parameters.

Thanks for the hint, I will check it.


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