where H is the magnetic field produced by the magnet and r is a vector from the center of the magnetic dipole to the location where the magnetic field is measured. The inverse cube nature of this equation is more readily seen by expressing the location vector r as the product of its magnitude times the unit vector in its direction ( r = | r | r ^ ^ ) so that: H ( r ) = 1 4 π π 3 r ^ ^ ( r ^ ^ ⋅ ⋅ m ) − − m | r | 3 .