matalb r square calculation

1.1 Calculation of R-squared of goodness of fit

%y_real:原来的数据
%y_pred:预测的数据
%判定系数r平方计算
%拟合优度
%236页
  meany = mean(y_real);
  SST = sum((y_real - meany).^2);
  SSE = sum((y_real - y_pred).^2);
  rSquare = 1-SSE/SST;