If I have an ODESolution, I can evaluate some variable at some t=5 with sol(5, idxs=sys.some_variable), but what if I have EvalAt(15)(sys.some_variable) - EvalAt(10)(sys.other_variable). This is a reasonable expression to evaluate on the solution. But sol(10, idxs=...) does not work, neither does sol[...]. How should I do it?
I looked into Function Building and Compilation (build_function) · Symbolics.jl, but it’s not obvious how to put that into practice.