  Kubo formula is used to get the d.c conductance of a statistical ensemble of
two dimensional clusters of the square lattice in the presence of random
magnetic fluxes. Fluxes traversing lattice plaquettes are distributed uniformly
between minus one half and plus one half of the flux quantum. The localization
length is obtained from the exponential decay of the averaged conductance as a
function of the cluster side. Standard results are recovered when this
numerical approach is applied to Anderson model of diagonal disorder. The
localization length of the complex non-diagonal model of disorder remains well
below 10 000 (in units of the lattice constant) in the main part of the band in
spite of its exponential increase near the band edges.
