Modular Forms

Fundamental domain · |j(τ)| coloring · Lattice sums · SL(2,ℤ) symmetry
Upper Half-Plane — |Δ(τ)| coloring
Lattice & Hecke orbit T_n
2.50
3
20
Modular: f((aτ+b)/(cτ+d)) = (cτ+d)ᵏ f(τ), ad−bc=1
Δ(τ) = q ∏(1−qⁿ)²⁴, q=e²πiτ
Hecke T_n: sublattices of index n → eigenforms