符号付偶数交点数列 { 6, 8, 10, 2, 4 } 射影交点座標 { (r,-π/2,0,0) , (r,-π/2-4π/5,0,0) , (r,-π/2-8π/5,0,0) , (r,-π/2-2π/5,0,0) , (r,-π/2-6π/5,0,0) } 交点間中点座標 { 0 , (R,π/2+2π/5,0,0) , 0 , (R,π/2-2π/5,0,0) , 0 , (R,π/2+4π/5,0,0) , 0 , (…