func G^{(%alpha &quot; , &quot; %beta)}_{ x_m x_n} = left[ matrix { arctan(%alpha) # arctan(%beta) ## x_m + x_n # x_m - x_n }right]
func G^{(%alpha &quot; , &quot; %beta)}_{ x_m x_n} = left[ matrix { arctan(%alpha) # arctan(%beta) ## x_m + x_n # x_m - x_n }right]