The CMS magnetic field measurements inside the hadronic calorimeter barrel (HB) had been carried out at CERN SX5 in November 2006 using the "fieldmapper" device developed at FNAL. The goal of these measurements was to provide field maps for several nominal field values with the precision of +/-5˙10 -4 T, usable for charged particle tracking.;An initial analysis of the measured data indicated presence of large systematic errors, which supposedly were related to fieldmapper misalignments and errors of calibration of the Hall probes.;An algorithm had been developed that allows to eliminate the systematic errors and to recover the actual field. The algorithm is based on the idea of making the measurements self-consistent (that is: the field must satisfy the Maxwell equations) by introducing fitted parameters for amplifier gain shifts and the probes position shifts. With the help of this algorithm, an analytic field representation, both for the axially symmetric and complete 3D field models, had been obtained which is within +/-4˙10 -4 T agreement with the measured field values in whole volume spanned in measurements except the most remote off center part of it, which makes only 6% of total volume.;Based on this analytic axially symmetric fit, a C++ code (BFit) is developed intended to be used in the CMS offline tracking. This code is recently integrated into the CMSSW software package.
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