What is the nature of the instability. Is it a time step instability (too large) or precision instability (time step too small). Also how can one be assured the problem does not lie in your modelling. Here I support what Ali is saying

see http://matlab.cheme.cmu.edu/2011/09/18/error-tolerance-in-numerical-solutions-to-odes/

Try ode45 solver

Thanks for feedback. Its a stiff problem so ode45 won't work. Either ode45s or ode15s.. But it can't go through the end of the time span..

So try to diminuate relative and absolute error tolerance by using odeset.

Thanks for your response. Yes, I tried all the options available in the odeset. The problem is: in some set of conditions its working but with other parameters it does not work. Better, do you have any idea how to analyse the instability with the Jacobian matrix?

well, If you can try to send the whole script to my email & I'm going try to fix it if i can.

@Mahmudul Hasan

ODE15s is used for solving stiff differential equations. If this scheme is causing instability then try to play with odeset, or use ode23tb instead, as it is more robust. Secondly if you can share the ODE you are solving then you may get more valuable comments for your problem.

What is the nature of the instability. Is it a time step instability (too large) or precision instability (time step too small). Also how can one be assured the problem does not lie in your modelling. Here I support what Ali is saying

see http://matlab.cheme.cmu.edu/2011/09/18/error-tolerance-in-numerical-solutions-to-odes/

Hello, Could you solve the problem with ODE15s? I have the same problem and don't know how solve it. Please can you help me.