Modular polynomial of Hilbert:

(To test the polynomials with the theta, you also need the files class-2, class-3, class-5 which contain the classes of the quotient SL_2(Ok\oplus\partial_K^{-1})/Gamma(2,4) for K=Q(sqrt(D)) and D=2,3,5 respectively.

Modular polynomial of Siegel:

• Streng invariants for l=2 and l=3 (readme);
• Theta invariants for l=3, 5 and 7 (readme);

You can find the code I wrote to compute the modular polynomials of Hilbert and of Siegel. The files lack of commentaries and explanations for now (sorry).