: rr0m,zr0m,rpam  ! rhot[m] = min(sqrt((r-rr0m)**2+(z-zr0m)**2), rpam); tor flux phi = pi*b0*rhot**2
 : b0              ! Bphi[T] @ rr0m[m]
 : q0,qa,alq       ! q = q0 + (qa-q0)*rhot**alq
 : nlim            ! number of points in first wall (rlim,zlim) polygon