/src/main/java/net/finmath/montecarlo/automaticdifferentiation/forward/RandomVariableDifferentiableAD.java
derivative = X.sqrt( ).invert( ).mult( 0.5) ;derivative = X.sub( Y).choose( zero, one) ;
derivative = X.sub ( Y ) .choose ( zero, one ) ;
break; case FLOOR: if(differentialIndex == 0) { derivative = X.sub(Y).choose(one, zero); } else { <extra_id_0> } break; case AVERAGE2: derivative = differentialIndex == 0 ? Y : X; break; case VARIANCE2: