A function such that

The most common use of a vector potential is the representation of a magnetic field. If a vector field has zero divergence, it may be represented by a vector potential.

A function such that

The most common use of a vector potential is the representation of a magnetic field. If a vector field has zero divergence, it may be represented by a vector potential.

Weisstein, Eric W. "Vector Potential."
From *MathWorld*--A Wolfram Web Resource. https://mathworld.wolfram.com/VectorPotential.html