  It has been shown that in larger than four space-time dimensions, soft
factors that relate the amplitudes with a soft photon or graviton to amplitudes
without the soft particle also determine the low frequency radiative part of
the electromagnetic and gravitational fields during classical scattering. In
four dimensions the S-matrix becomes infrared divergent making the usual
definition of the soft factor ambiguous beyond the leading order. However the
radiative parts of the electromagnetic and gravitational fields provide an
unambiguous definition of soft factor in the classical limit up to the usual
gauge ambiguity. We show that the soft factor defined this way develops terms
involving logarithm of the energy of the soft particle at the subleading order
in the soft expansion.
