/src/main/java/net/finmath/montecarlo/automaticdifferentiation/forward/RandomVariableDifferentiableAD.java
derivative = zero;
derivative = Y;
case ADDPRODUCT: if(differentialIndex == 0) { derivative = one; } else if(differentialIndex == 1) { derivative = Z; } else { <extra_id_0> } break; case ADDRATIO: if(differentialIndex == 0) { derivative = one; } else if(differentialIndex == 1) {