Well, my understanding is that MATLAB for example, you create a model in simulink, then you specify the duration of the simulation and the result is all the data from t=0 to your specified time limit. This is a passive simulation. You let it run and it does so. What I'm after is a simulation where it's like having the physical circuit in your hands - so you can turn various components on and off, use various components thereby changing their power consumption etc... so basically I want to have a virtual model that you can play with.