[SciPy-User] Help!!!!!! having NEW problems with ODEINT

[Laura Matrajt]

Laura Matrajt <matrajt <at> gmail.com> writes:

> 
> Kevin Dunn <kgdunn <at> gmail.com> writes:
> 
> > Hi Laura,
> > 
> > There's an example in the SciPy documentation on using a Jacobian:
> > http://docs.scipy.org/doc/scipy/reference/generated/scipy.integrate.ode.html
> > 
> > This is for the ``ode`` function, not the ``odeint`` function though.
> > 
> > I've just posted an example on using ``ode`` with coupled ODEs, no Jacobian
> > over here:
> >
>
http://scipy-central.org/item/13/0/integrating-an-initial-value-problem-multiple-odes
> > 
> > Hope that helps,
> > Kevin
> > 
> 
> Hi Kevin,
>  the example was good. I now have implemented my Jacobian. Thank you very
much!!!!!
> 


Hi all:
sorry to bother you again! I implemented the Jacobian as Anne kindly suggested
to me with the help of Kevin's pointers to the correct webpage AND I increased
the maximum number of steps as Warren kindly said.
I am now getting a new message:

lsoda--  warning..internal t (=r1) and h (=r2) are
       such that in the machine, t + h = t on the next step  
       (h = step size). solver will continue anyway
      In above,  R1 =  0.1209062893646E+03   R2 =  0.9059171791494E-18

It is just a warning, and my code continues to run. But I am really worried
about this being a bug. The problem is that I am coupling a system of ODE's with
a stochastic process. Mainly, I simulate a day of an epidemic, stop the
integrator, change some of the initial conditions stochastically (not just
randomly, I do follow some rules) and I run the ODE again and so on.
 I have run this millions of times (and I am not exagerating about the millions)
and it doesn't produce any warnings, but every now and then (~15 times) it does
it. I don't know if this is a bug or just that not all of my domain will be good
for the ODE's...
If anyone has any suggestion of how to think about this problem, I will really
appreciate it!!!!!!
thanks to all the people that replied to me previously, you helped me sooo much
already!