Is there a null point at the center of a ring magnet?

I have a code to calculate the ring magnet field. Figure 1 shows the field distribution. It can be seen that the field on the axis changes sign, therefore, the field vanishes in a certain region near the magnet, but not in the center.

The image shown results from the use of ring magnets over a ferrocell. It is not a true representation of the space occupied by a magnetic field.[1]

There is no null point at the center of a ring magnet.

Reference: [1] Alberto Tufaile, Timm A. Vanderelli, and Adriana Pedrosa Biscaia Tufaile. Light Polarization Using Ferrofluids and Magnetic Fields. Hindawi. Advances in Condensed Matter Physics, Volume 2017, Article ID 2583717, 7 pages. https://doi.org/10.1155/2017/2583717