Non negativity in LSODE

[Balachandra Bhadravathi Krishnamurthy]

Hi,
	I am solving a relatively simple ODE system and sometimes the 
variables go negative (on the order of 1e-10). I know that its almost 
zero, but it would be great if I could somehow enforce the non-negativity 
constraints for all the variables. I tried doing that in DASSL (although 
the system is pure ODE), but even with an exact initial condition for 
xdot_0, DASSL complains that it can't compute YPRIME.

I am calling LSODE from a C++ program. I am using Octave version 2.1.57 
compiled with gcc 3.4.1 on RedHat 9.

Thanks,
Bala



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