  The solution is given for the $c=3$ topological matter model whose underlying
conformal theory has Landau-Ginzburg model $W=-\qa (x^4 +y^4)+\af x^2y^2$.
While consistency conditions are used to solve it, this model is probably at
the limit of such techniques. By using the flatness of the metric of the space
of coupling constants I rederive the differential equation that relates the
parameter \af\ to the flat coordinate $t$. This simpler method is also applied
to the $x^3+y^6$-model.
