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

[ms]

Hello,

I am trying to integrate a large (50-200 equations) system of chemical
kinetics ODEs using scipy.integrate.odeint.

The qualitative behaviour of the system looks sensible, but mass is not
conserved at all -it increases a lot during time, sometimes wildly,
depending on parameters.

This puzzles me, and I am *very new* to this kind of problems; however
reading here and there it seems that stiff ODEs can show this kind of
artefacts. I checked the equation values and looks stiff;
infodict['mused'] is always 1... so odeint sees it as stiff too. This
does not look good.

I wonder what can one do to tame this beast. Any hint?

thanks!
m.