  The analytical approach developed by us for the calculation of the phase
diagram for the Anderson localization via disorder [J.Phys.: Condens. Matter
14, 13777 (2002)] is generalized here to the case of a strong magnetic field
when $q$ subbands ($q=1,2,3$) arise. It is shown that in a line with the
generally accepted point of view, each subband is characterized by a critical
point with a divergent localization length $\xi$ which reveals anomaly in
energy and disorder parameters. These critical points belong to the phase
coexistence area which cannot be interpreted by means of numerical
investigations. The reason for this is a logical incompleteness of the
algorithm used for analysis of a computer modelling for finite systems in the
parameter range where the finite-size scaling is no longer valid.
