− ( t ( 2 ) − t ( 3 ) ) ( t ( 1 ) − t ( 4 ) ) t ( 1 ) t ( 2 ) t ( 3 ) t ( 4 ) {\displaystyle -{\frac {(t(2)-t(3))(t(1)-t(4))}{{\sqrt {t(1)}}{\sqrt {t(2)}}{\sqrt {t(3)}}{\sqrt {t(4)}}}}}
