τ → qk = 1/k’ ⇨ K’( k ) = ( 2/( 1+k ) )K( ( 1-k )/( 1+k ) ) : Landen = k’K( k ) ⇨ τ = K’( k )√-1/K( k ) = k’√-1 = ( 1+√-3 )/2 ⇨ q = exp( π√-1τ) = exp( -√-3π/2 )√-1 1/q 〜 ( 4/k )^2-8 : Jacobi に代入して・・・