Nikolas, I haven't touched the code in a while, so it might not run with Julia 0.3, but you might look here for some ideas:
https://github.com/tshort/Sims.jl It's a way to create ODE's from components, including electrical models. Models are custom expressions built up from symbolic objects. On Tue, Oct 14, 2014 at 2:14 PM, Nikolas Tezak <[email protected]> wrote: > Hi all, > > in my research I run numerical simulations (ODEs and SDEs) for circuit > models that can be composed, i.e., > each system has an ode that modifies in-place the elements of an output > array based on the current state variable. > Moreover, dimensionality of each system may vary. > > function sys1_ode(t, x, xdot) > xdot[1] = # some function of x, t > xdot[2] = # some other function of x, t > end > > > function sys2_ode(t, x, xdot) > xdot[1] = # some expression with x, t > xdot[2] = # some other expression with x, t > xdot[3] = # some other expression with x, t > end > > > What I would like to do is use metaprogramming to construct a combined ode > for both systems where the state vectors are just stacked. For each system I > compute the offset within the state vector (0 for sys1 and 2 for sys2) and > then modify and recombine the function code as follows > > function sys12_ode(t, x, xdot) > xdot[1+0] = # some expression with x[1:2], t > xdot[2+0] = # some other expression with x[1:2], t > xdot[1+2] = # some expression with x[1+2:3+2], t > > xdot[2+2] = # some expression with x[1+2:3+2], t > xdot[3+2] = # some expression with x[1+2:3+2], t > > end > > > So far, that would seem to be quite straightforward and I think I could get > this working by calling code_lowered(sys1_ode) and using the rewritten > output to construct an AST for the combined function. > > The difficulty now arises when my sys1 and sys2 odes are defined with some > internal parameters that are not passed as an argument but rather through a > closure from the surrounding scope, i.e. I have some ode factory: > > funcion make_sys1_ode(p1, p2) > function sys1_ode(t, x, xdot) > xdot[1] = # some expression with x, t AND p1, p2 > xdot[2] = # some expression with of x, t AND p1, p2 > end > sys1_ode > end > > Given the constructed sys1_ode method is there someway to dynamically access > the captured variables, i.e. those that come from its closure? > Otherwise, I suppose I could resort to passing parameters via an extra ODE > argument, but it would be super nice if I could avoid this. > The reason why I am trying to implement things this way is to speed up ODE > evaluation for very large complex (i.e. nested) circuits by expanding out > all ODE bodies into a single function. > > I hope this write-up makes sense. > Thanks, > Nik >
