With given ferromagnetic cylinder we known its hysteresis curve. Then we use coils to create magnetic field. How do we compute the overall magnetic field?

I computed the magnetic field on the boundary of this cylinder.

Then at each point of the cylinder I subtracted magnetization according to the hysteresis curve.

Then I multiplied vector of magnetization with small volume.

Finally I computed magnetic field from magnetic dipole.
Is this approach correct? Any comments are welcome. Note: the material is isotropic.