Zdroj TeX:

\small f(X,Y)=\left [x_1-y_1,x_2-y_2,x_3-y_3 \right ] =\left [ x_1-y_1,x_2-y_2, \frac{1}{2} \left\{(x_1-y_1 )+(x_2-y_2 ) \right\} \right ]