Hi Bryce, All methods that I am aware of require either assumptions, estimates, or maybe iterative methods of determining the center reference point (such as your r-position reference).
You can perform the calculation around one axis at a time, so you could calculate m_z for positions with reference to the global Z-axis with the following Field Calculator commands:
- Function > Scalar: X (global X position)
- Vec? > VecX
- Function > Scalar: Y (global Y position)
- Vec? > VecY
- + (this is a radial position vector, you can add VecZ position to obtain full position)
- Quantity > CurrentDensity (J)
- Scal? > ScalarZ (integral needs to be performed on scalar components separately)
- Geometry > Volume Object
You can then repeat for X and Z axis. Apply the 1/2 scaling at any time.