add docs for input-output handling #2918
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addresses #2852
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| ModelingToolkit can generate the dynamics of a system, the function ``M\dot X = f(x, u, p, t)`` above, such that the user can pass not only the state ``x`` and parameters ``p`` but also an external input ``u``. To this end, the function [`generate_control_function`](@ref) exists. | ||
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| This function takes a vector of variables that are to be considered inputs, i.e., part of the vector ``u``. Alongside returning the function ``f``, [`generate_control_function`](@ref) also returns the chosen state realization of the system after simplification. This vector specifies the order of the state variables ``x``, while the user-specified vector `u` specifies the order of the input variables ``u``. |
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returns the chosen state realization of the system after simplification. This vector specifies the order of the state variables
x, while the user-specified vectoruspecifies the order of the input variablesu.
Maybe I'm not the intended audience for this, but I've been reading and studying and rereading and I'm still completely lost on this bit. What does "chosen state realization" mean? What is the order of a state variable, why does it matter?
A simple example of generate_control_function usage would help tremendously.
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What does "chosen state realization" mean?
In a simple scenario, an MTK model may contain 100's of variables, but MTK chooses only position, velocity to be part of the state position, velocity as the state, and that they appear in that order, so that you can pass numerical values
x = [
0.4 # Position of car
0.7 # Velocity of car
]
f(x, u, p, t)
addresses #2852