Talk:J-invariant

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[edit] Notation bugs

There is a notational problem in this and related articles; standard notation seems to be that J=g_2^3/\Delta and j=1728 J. I'll try to review correctness/fix this when I have the chance. (where g_2=60 \sum(m\tau+n)^{-4} linas 03:54, 20 Jun 2005 (UTC)

If It can be of any help I think I remember there are two notations for Eisenstein series too: g2 or G2, correspoing to different conventions (leading coefficient one, integer coefficients, norm 1 etc...)

Why is the elliptic modular function attributed to Klein? The fundamental domain of the modular group was known to Gauss. It was studied by Kummer, and by Hermite (1858) in connection with the solution of 5-ics, and defined by Dedekind in a remarkable paper in Crelle ?1878. Klein became involved after Dedekind. He defined j in terms of absolute invariants of Int dy/y, y^2 = 4-ic in x. After a fw pages he reverts to Dedekind's definition. [John McKay] May be Atkin should be consulted?]