/src/main/java/net/finmath/montecarlo/automaticdifferentiation/forward/RandomVariableDifferentiableAD.java
derivative = Y.sub( Z) ;derivative = one;
derivative = one;
derivative = X.invert().squared().mult(-1); break; case AVERAGE: derivative = one; break; case CONDITIONAL_EXPECTATION: <extra_id_0> break; case VARIANCE: derivative = X.sub(X.getAverage()*(2.0*X.size()-1.0)/X.size()).mult(2.0/X.size()); break; case STDEV: derivative = X.sub(X.getAverage()*(2.0*X.size()-1.0)/X.size()).mult(2.0/X.size()).mult(0.5).div(Math.sqrt(X.getVariance()));