  The calculation of the demagnetization field is crucial in various
disciplines, including magnetic resonance imaging (MRI) and micromagnetics. A
standard method involves discretizing the spatial domain into finite difference
cells and using demagnetization tensors to compute the field. Different
demagnetization tensors can result in contributions from adjacent cells that do
not approach zero, nor do their differences, even as the cell size decreases.
This work demonstrates that in three-dimensional space, a specific set of
magnetization tensors produces the same total demagnetization field as the
Cauchy principal value when the cell size approaches zero. Additionally, we
provide a lower bound for the convergence speed, validated through numerical
experiments.
