of this mode is where the tfo distribution has only two values the desired tfo and the desired tfo plus 180 degrees controlled eccentricity and tfo this mode requires a non rotating stabilizer with independently controllable eccentricity and tfo such as in fig6 a e the desired hole curvature and direction are given calculate the eccentricity required by the particular tool parametrics to drill the desired curvature set the stabilizer to this calculated eccentricity in the desired tfo direction controlled vane force and tfo this mode requires a non rotating stabilizer with independently adjustable vanes such as in fig7 a d the desired hole curvature and direction are given calculate the required individual vane force or position required to produce that force as a function of vane tfo required to drill the desired curvature and direction if the vanes are hydraulically operated either the vane forces or the vane positions are set if the vanes are mechanically operated the vane positions are set other modes many other analytical deterministic modes exist too numerous to detail and are included in the nature of the invention all deterministic processes produce imperfect results or residual error however small adaptive mode the adaptive mode is a supplementary mode and can be used in conjunction with any of the above deterministic modes to reduce any errors in the analytical models and correct for unaccounted for factors such as formation drillability anisotropy and can be used with any control mechanism the basic process is to compare measured curvature and tfo of the actual drilled hole with the planned or desired values of curvature and tfo and use any residual differences to modify the control parameters in such a manner as to offset the residual error this adaptive mode can be reiterated on each.