A method and apparatus for applying adaptive non-linear repeatable runout compensation
in a disk drive is provided. In one embodiment, the present invention provides
a disk surface having a track written thereon, wherein the track includes repeatable
runout. A non-linear converge gain is applied to compensate for the repeatable
runout. In one embodiment, the converge gain is based upon an amplitude of a position
error signal associated with the repeatable runout at a frequency of rotation of
the disk surface (or multiple thereof).