A -invariant meromorphic function on the space of all complex symmetric matrices with Positive Imaginary Part. In 1984, H. Umemura expressed the Roots of an arbitrary Polynomial in terms of elliptic Siegel functions.
References
Iyanaga, S. and Kawada, Y. (Eds.). ``Siegel Modular Functions.'' §34F in
Encyclopedic Dictionary of Mathematics. Cambridge, MA: MIT Press, pp. 131-132, 1980.