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I'm confused about the states' order when I use State::getY() or similar methods.
I found Y=Q+U+Z, but the states' orders inside Q,U,Z are hard to know. Is there a method to output states' name with the same sequence order of Y?
I tried Component::getStateVariableNames. It can output same states as in Opensim model, but obviously different from getY().
Thanks for reading.

It is generally advisable to get the values of state variables through the OpenSim API. For example, you can ask a Muscle for its fiber length using getFiberLength() (https://simtk.org/api_docs/opensim/api_ ... 61455143e8). It would be helpful to know what you are trying to do.

tkuchida wrote: ↑

Thu Nov 21, 2019 3:07 am

It is generally advisable to get the values of state variables through the OpenSim API. For example, you can ask a Muscle for its fiber length using getFiberLength() (https://simtk.org/api_docs/opensim/api_ ... 61455143e8). It would be helpful to know what you are trying to do.

Thanks for replying. I was actually trying to get state derivatives, but they were different from what I expected. So I checked states setting, and found they were also different as I expected. The differences were mainly states' order.

Still not sure what you're trying to do, but there are some methods in OpenSim's Component interface that might be helpful:
- getStateIndex(), https://simtk.org/api_docs/opensim/api_ ... e65c5a1b5a
- getStateVariableSystemIndex(), https://simtk.org/api_docs/opensim/api_ ... 7d5938284d
- getDiscreteVariableIndex(), https://simtk.org/api_docs/opensim/api_ ... 1bc698cd88
- etc.
You could also interpret Y by changing states using OpenSim methods and seeing which entries in Y change, but there's no guarantee that the order/indices of state variables will remain the same between software releases. Some additional information can be found in the Simbody documentation, https://github.com/simbody/simbody/tree ... imbody/doc.

tkuchida wrote: ↑

Thu Nov 21, 2019 9:55 am

Still not sure what you're trying to do, but there are some methods in OpenSim's Component interface that might be helpful:

Yes, it helps. I solved my problem. Thanks.