Check if Dommaschk potential can describe magnetic fields not "centered" about R=1

[dpanici]

Dommaschk potentials are "centered" about R=1, but this has implications for stellarator symmetry when using these fields, or even for just describing the field at all. If a magnetic field is not centered about this same radial position, there may be issues in fitting the field assuming symmetry (or even fitting the field at all, even if not stellarator symmetric)

https://www.sciencedirect.com/science/article/pii/0010465586901098