One of our users is looking for the ability to do Periodic BCs... but where instead of have _equality_ on either side of the periodic boundary you instead have a constant offset.

So if u_i is periodic with u_j you would then have the constraint that u_j = u_i + c ... where c is that specified offset.

What's really tricky is that they want a different constant value for each variable.

Anyone see a way to make that happen?