ODE15S - How to pass parameters out?

Hi, Can anyone tell me how I can pass parameters out of a ODE15S timestep when they are not being calculated as part of the differential equation but are subsidiary values. I can write them out from within each loop, but what I really want to do is write them out at the end of a successful timestep (i.e. not get the values calculated with trial time step sizes)? Thanks for any advice, Rebecca