  We show that all (n-component) KP tau-functions, which are related to the
twisted loop group of $GL_n$, give solutions of the Darboux-Egoroff system of
PDE's. Using the Geometry of the Grassmannian we construct from the
corresponding wave function the deformed flat coordinates of the Egoroff metric
and from this the corresponding solution of the Witten-Dijkgraaf-E. Verlinde-H.
Verlinde equations.
