Daniel Dudt

Try implementing Eq. 17-18 of [Peraza-Rodriguez et al. _Phys. Plasmas_ 2017](https://doi-org.ezproxy.princeton.edu/10.1063/1.4986447) It should be a simple linear system solve to get the Fourier-Zernike coefficients of the vector potential as: $\nabla...

Can we benchmark against COBRAVMEC for the Heliotron example?

Related to #849. I think it would be good to have a standalone util function, and then `SplineProfile.change_resolution` can call that under the hood.

> with the usual automatic scaling the variable the optimizer sees is `x / |f'(x)|` this is basically making a new function `g(y=ax) = f(ax)` so the optimizer sees `y...

> Is it better to just open a new PR rather than having a "revert all commits" commit? too late now I suppose It was only 3 commits so not...

Slightly tangential comment: `deriv_mode="batched"` appears to compute the Jacobian wrt only the optimization variables. `deriv_mode="blocked"` however, appears to compute each objective's Jacobian wrt all parameters related to that objective (even...

> I think you'll also need to update master_compute_data with the new variables and name changes I didn't update this yet but the tests are passing. Is that a bug...

Changed the density to use the volume-average instead of a line-average and updated the master compute data, so this PR should be good to go now

> They seem ok to me. Running on the actual w7x equilibrium I get the scale for B is 3.11 T which is pretty close to the actual volume average...

I'm having an issue with the new test in this PR after updating with `master` where the code gets stuck in some infinite loop. I can make the test pass...