I have a system of ODE, which is rather heterogeneous. That is one equation corresponds to some background property of a system, and then there are many (say, hundred) equations for individual evolution of components of the system. Thus, error estimate is quite different for the various equations - first equation is large and basically has no error for any time step, while the rest are actually important to determine the error.
So, I’d like to produce my own error estimate or adaptive step size control. What would be the suggestions? Actually, in my particular case, I don’t need something very smart – I more or less need to estimate the errors only for part of the equations I am solving.
Attempt to use the
internalnorm does not help – as far as the error estimate internally uses maximum of the
u[i], it anyway scales the error estimate in the same way for all equations – that is not what I need.