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