I'm looking for alternatives to Matlab/Simulink and Dymola for simulating a non-linear dynamic system. I know it's possible to implement the time-domain behavior without a lot of code and a good simulator template which would do fixed-step simulation, but I don't want to re-invent the wheel.
I'm basically looking for a template library that allows me to define my system, pass it to a simulator and analyze the results using other C++ libraries. The results would feed a system identifcation code that adjusts the simulated system to data gathered in experiments. Later, I'd like to use the same set of libraries to design a controller for my real system.
I don't want to use Matlab/Simulink or Dymola because I don't have access to them at home and I don't want to buy them. Matlab, Simulink, system identification toolbox and all other toolboxes I might need for this project are way too expensive for me as a single person.
A google search revealed some candidates, but they don't seem to be very active. The most recent update I found was in 2011. Does anyone here actually use such a library and can recommend one?