code: public static double geometricMean(DoubleTuple t)
      {
          double product = DoubleTupleFunctions.reduce(t, 1.0, (a,b) -> (a*b));
          return Math.pow(product, 1.0 / t.getSize());
      }
docs: Returns the geometric mean of the given tuple
  
  @param t The input tuple
  @return The mean