τ = √-4η( τ = √-4 ) = 1/( 2^( 5/8 )A.G.M.( 1 , √2 )^( 1/2 ) ) = 0.5923827813 ・・・ E4( Z[ τ = √-4 ] ) = ( 33/16 )/A.G.M.( 1 , √2 )^4 = ( 11/16 )E4( Z[ τ = √-1 ] ) = 1.0008369884 ・・・
