title: Correlation coefficient of matrices
body: <p>would someone be able help me please, as I'm getting errors on this code and I don't know where it is going wrong. I am getting the following:
  errors C2059: syntax error : 'return', 
  error C2334: unexpected token(s) preceding '{'; skipping apparent function body,
  error C2039: 'rtn' : is not a member of 'corr_coefficient'
  see declaration of 'corr_coefficient'
  Thank you.</p>
  
  <pre><code>using namespace std;
  
  class corr_coefficient
  {
      matrix x, y;
      double sum, C, corr[5];
      int j;  
  public:
      double calc_mu(matrix x, int j=0);
      double calc_covariance(matrix x, matrix y, int j); 
      double calc_correlation();
      double StandardDeviation(matrix a, int j=0);
      double return(int i){return corr[i];
      };
      corr_coefficient(matrix x, matrix y);
      };
  
  double corr_coefficient::calc_mu(matrix x, int j)
  {
      sum=0;
      for(int i=0; i&lt;C; i++)
      {
          sum = sum+x(i,j);
      }
      return sum/C;
  }
  
  double corr_coefficient::calc_covariance(matrix x, matrix y, int j)
  {
      double mux=calc_mu(x,0); 
      double muy=calc_mu(y,j); 
      sum=0;
      for (int i=0; i&lt;C; i++)
      {
          sum=sum+(x(i,0)-mux)*(y(i,j)-muy);
      }
      return sum/(C-1); 
  }
  double corr_coefficient::StandardDeviation(matrix a, int j)
  
  {
      double mua=calc_mu(a,j); 
  
      sum=0;
      for (int i=0; i&lt;C; i++)
      {
          sum=sum+((a(i,j))-mua)*((a(i,j))-mua);
      }
      return sqrt(sum/(C-1));
  }
  corr_coefficient::corr_coefficient(matrix x, matrix y)
  {
      C=35;
      for (int j=0; j&lt;5; j++)
      {
          corr[j]=calc_covariance(x, y, j)/(StandardDeviation(x, 0)*StandardDeviation(y, j));
      }
  }
  </code></pre>