  The Anderson transitions in a random magnetic field in three dimensions are
investigated numerically. The critical behavior near the transition point is
analyzed in detail by means of the transfer matrix method with high accuracy
for systems both with and without an additional random scalar potential. We
find the critical exponent $\nu$ for the localization length to be $1.45 \pm
0.09$ with a strong random scalar potential. Without it, the exponent is
smaller but increases with the system sizes and extrapolates to the above value
within the error bars. These results support the conventional classification of
universality classes due to symmetry. Fractal dimensionality of the wave
function at the critical point is also estimated by the equation-of-motion
method.
