Quasi-steady electromagnetics including filamentized approximations, Biot-Savart, and Grad-Shafranov.

Above is the B-field of a Helmholtz coil, calculated with cfsem.
On the left, the red dashes outline where the B-field magnitude is within 1% of its value at (r=0, z=0), and the black dots show where the coils intersect the r-z plane.
[Full example here](python/examples.md#helmholtz-coil-pair).