| ... | ... | @@ -974,26 +974,18 @@ integral form of $\mathbf{B}=\nabla\times \mathbf{A}$: | 
| 
 | 
 | 
where the difference operators *Δ*<sub>ix</sub>, *Δ*<sub>iy</sub> 
 | 
| 
 | 
 | 
and *Δ*<sub>iz</sub> are given by
 | 
| 
 | 
 | 
 | 
| 
 | 
 | 
*Δ*<sub>ix</sub>X=X(iz,iy,ix+1)-X(iz,iy,ix)
 | 
| 
 | 
 | 
*Δ*<sub>ix</sub>X=X(ix,iy,iz+1)-X(ix,iy,iz)
 | 
| 
 | 
 | 
 | 
| 
 | 
 | 
*Δ*<sub>iy</sub>X=X(iz,iy+1,ix)-X(iz,iy,ix)
 | 
| 
 | 
 | 
*Δ*<sub>iy</sub>X=X(ix,iy+1,iz)-X(ix,iy,iz)
 | 
| 
 | 
 | 
 | 
| 
 | 
 | 
*Δ*<sub>iz</sub>X=X(iz,iy,ix+1)-X(iz,iy,ix)
 | 
| 
 | 
 | 
*Δ*<sub>iz</sub>X=X(ix,iy,iz+1)-X(ix,iy,iz)
 | 
| 
 | 
 | 
 | 
| 
 | 
 | 
and (*Â*<sub>*x*</sub>, *Â*<sub>*y*</sub>, *Â*<sub>*z*</sub>) 
 | 
| 
 | 
 | 
are the cell-edge integrals
 | 
| 
 | 
 | 
 | 
| 
 | 
 | 
  
 | 
| 
 | 
 | 
 | 
| 
 | 
 | 
$$\hat{A}_x(\mathtt{iz,iy,ix})=\int\limits_\mathtt{g->x[ix]}^\mathtt{g->x[ix+1]}
 | 
| 
 | 
 | 
A_x(x,\mathtt{g->y[iy]},\mathtt{g->z[iz]})dx$$
 | 
| 
 | 
 | 
 | 
| 
 | 
 | 
$$\hat{A}_y(\mathtt{iz,iy,ix})=\int\limits_\mathtt{g->y[iy]}^\mathtt{g->y[iy+1]}
 | 
| 
 | 
 | 
A_y(\mathtt{g->x[ix]},y,\mathtt{g->z[iz]})dy$$
 | 
| 
 | 
 | 
 | 
| 
 | 
 | 
$$\hat{A}_z(\mathtt{iz,iy,ix})=\int\limits_\mathtt{g->z[iz]}^\mathtt{g->z[iz+1]}
 | 
| 
 | 
 | 
A_z(\mathtt{g->x[ix]},\mathtt{g->y[iy]},z)dz$$
 | 
| 
 | 
 | 
 | 
| 
 | 
 | 
The  *Â*'s
 | 
| 
 | 
 | 
The $\hat{A}$'s are usually easier to compute than the face-averaged
 | 
| 
 | 
 | 
magnetic field components directly. Even if the $\hat{A}$'s are
 | 
| 
 | 
 | 
approximated but otherwise set *unambiguously* on cell edges in the grid
 | 
| ... | ... |  |