OpenCV- Working with OpenCV

Using my previous posts Class file and this reference: http://people.revoledu.com/kardi/tutorial/DecisionTree/how-to-measure-impurity.htm float computeGiniIndex(Mat r, Mat g, Mat b)     {         float giniIndex = 0.0;         float frequency = getFrequencyOfBin(r);         for( int i = 1; i < histSize; i++ )         {             float Hc = abs(getHistogramBinValue(r,i));             giniIndex += Hc*Hc;         }         frequency = getFrequencyOfBin(g);         for( int i = 1; i < histSize; i++ )         {             float Hc = abs(getHistogramBinValue(g,i));  ...