CustomExternalForce defined functions....

[Kasra Momeni]

How can I define an external force which varies as a function of simulation time?

[Peter Eastman]

If you want it to explicitly be a function of the time, that isn't possible. It's a good suggestion though, so go ahead and enter it into the feature request tracker.

What you can do, though, is define a global parameter and make the force depend on that. Then over the course of your simulation, you can periodically update it by calling setParameter() on the Context.

Peter

[Saurabh Belsare]

Hi Dr. Eastman,

Has this feature been implemented? If not, if I use the global parameter, as you have suggested, is there a cost associated with setting the parameter at, say each time step?

Thank you.

[Peter Eastman]

The cost of doing that should be pretty small. Global parameters are designed to be efficient to update.

Peter

[Saurabh Belsare]

Hi Dr. Eastman,

I think I've been able to add the force I'm looking for using the global parameter update, as you've suggested.

Thank you.