I'm trying to develop a modified energy minimizer where, in addition to enforcing typical energetic interactions, I want to constrain distances between particular atoms. So I think I need to have a function associated with each constraint and I would like to use a parabolic/quadratic function to describe the behavior of the constraints. Is there a quadratic function in the constraints package of PyRosetta? I was just using the tab-autocomplete feature in iPython to look for something like this but I can't seem to find what I am looking for. A Gaussian function might work but I would rather use a quadratic function instead if it exists. Thank you for your consideration.