Question on how to define equation system in DiffEq using Matrix form

[ChrisRackauckas]

@kwwong333

We have the form of the ODE that is designed to solve in Diffeq. However, it is a matrix of equations instead of just a few equations. Previously, this was solved using a loop, and the coefficient in the matrix was updated correspondingly from one timestep to another. How is this accomplished in Diffeq?

It’s shown in the first tutorial:

https://diffeq.sciml.ai/stable/tutorials/ode_example/#ode_other_types

@kwwong333

Another way is to redefine the ODE system at every timestep, is there any computational burden for doing that, and is there a better way of achieving this?

No, wiping the caches would make it slow.

@kwwong333

Suppose we can describe the ODE system and I have an artificial source term that must be calculated in a function (which has some complex logic) at each timestep. I cannot call that function in symbolic language and that requires me again to redefine my ODE problem at every timestep. What is the proper way for revising the matrix/problem definition?

Just make it a function of t, or use callbacks.