Modular polynomials are a good tools in elliptic curves. I need to find the roots of $l$-th classical modular polynomial $\Phi_l(X,Y)$ over the prime field. Unfortunately the coefficients of these polynomials are so large and I haven't it. But I have an access to Atkin modular polynomials database. Now this is my question:
What is the relation between roots of classical and Atkin modular polynomial over the prime field?
