ヤコビの楕円関数
− dn 2  ( u ) + m 1 = − m cn 2  ( u ) = m sn 2  ( u ) − m {\displaystyle -\operatorname {dn} ^{2}(u)+m_{1}=-m\;\operatorname {cn} ^{2}(u)=m\;\operatorname {sn} ^{2}(u)-m}
− m 1 nd 2  ( u ) + m 1 = − m m 1 sd 2  ( u ) = m cd 2  ( u ) − m {\displaystyle -m_{1}\;\operatorname {nd} ^{2}(u)+m_{1}=-mm_{1}\;\operatorname {sd} ^{2}(u)=m\;\operatorname {cd} ^{2}(u)-m}