# Class-Numbers of Complex Quadratic Fields

• H. M. Stark
Conference paper
Part of the Lecture Notes in Mathematics book series (LNM, volume 320)

## Abstract

Let E be an elliptic curve
$$y^2 = 4x^3 - g_2 x - g_3 ,\Delta = g_2^3 - 27g_3^2 \ne 0,$$
in Weierstrass normal form. The curve may be parametrized by the Weierstrass ℘-function, x = ℘(z), y = ℘′(z). The function ℘(z) is a doubly periodic function whose periods form a lattice
$$\Lambda = \{ \omega _1 ,\omega _2 \} = \{ a\omega _1 + b\omega _2 |a,b \in \mathbb{Z}\}$$
where ω12 ∉ ℝ and for convenience we assume that ω1 and ω2 are so ordered that Im(ω12) > 0. We then have the relations
$$g_2 = 60\sum\limits_\omega {'\omega ^{ - 4} } ,g_3 = 140\sum\limits_\omega {'\omega ^{ - 6} } ,$$
(1)
where the summations are over all ω ∈ Λ other than ω = 0, and
$$\wp (z) = \frac{1} {{z^2 }} + \frac{{g_2 }} {{20}}z^2 + \frac{{g_3 }} {{28}}z^4 + \frac{{g_2^2 }} {{1200}}z^6 + ....$$
(2)
.

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