code: public double matthewsCorrelation(int outputNum) {
          assertIndex(outputNum);
  
          return EvaluationUtils.matthewsCorrelation(truePositives(outputNum), falsePositives(outputNum),
                          falseNegatives(outputNum), trueNegatives(outputNum));
      }
docs: Calculate the Matthews correlation coefficient for the specified output
  
  @param outputNum Output number
  @return Matthews correlation coefficient