docs: public static double sampleCorCoeff(Vec xData, Vec yData)
      {
          if(yData.length() != xData.length())
              throw new ArithmeticException("X and Y data sets must have the same length");
  
          double xMean = xData.mean();
          double yMean = yData.mean();
  
          double topSum = 0;
  
          for(int i = 0; i < xData.length(); i++)
          {
              topSum += (xData.get(i)-xMean)*(yData.get(i)-yMean);
          }
  
  
          return topSum/((xData.length()-1)*xData.standardDeviation()*yData.standardDeviation());
      }