Computes the analytic magnetic field from a single wire
point
(vector float)current
(float)mu0
(float)normal
(vector float)<Source coilSource>
kind = wireFieldEqn
point = [0.0, 0.0, 1.0]
mu0 = 1.26e-6
normal = [1.0, 0.0, 0.0]
current = 1.0
</Source>