code: public DiscreteFactor apply(DiscreteFactor featureFactor) {
      return featureFactor.add(means.product(-1.0)).product(inverseStdDevs).add(finalOffset)
          .product(rescalingFactor);
    }
docs: Applies this standardization procedure to the features in
  {@code featureFactor}.
  
  @param featureFactor
  @return