  We illustrate the stochastic method for solving the Schwinger-Dyson equations
in large-N quantum field theories described in ArXiv:1009.4033 on the example
of the Gross-Witten unitary matrix model. In the strong-coupling limit, this
method can be applied directly, while in the weak-coupling limit we change the
variables from compact to noncompact ones in order to cast the Schwinger-Dyson
equations in the stochastic form. This leads to a new action with an infinite
number of higher-order interaction terms. Nevertheless, such an action can be
efficiently handled. This suggests the way to apply the method of
ArXiv:1009.4033 to field theories with U(N) field variables as well as to
effective field theories in the large-N limit.
