(参考) ctnt-summer.math.uconn.edu/wp-content/uploads/sites/1632/2016/02/coxctnt.pdf Gauss and the Arithmetic-Geometric Mean David A. Cox Department of Mathematics and Statistics Amherst College dacox@amherst.edu CTNT, August 10, 2016
P20/22 Fundamental Domains Gauss knew that k′(τ)2 was Γ(2)-invariant, and he also knew the fundamental domain of Γ(2). This fundamental domain appears twice in his collected work
