The meaning of << operator in matrix operation : I see some codes in using `<<` with `Mat_` for matrix operations. 

Example#A: 

    cv::Mat_<double> myMat_ = ( cv::Mat_<double>(3, 3) << 
        1.0, 2.0, 3.0,
        4.0, 5.0, 6.0,
        7.0, 8.0, 9.0);
Example#B:

    cv::Mat myMat = (Mat_<float>(2,3)<<1,skew,-0.5*SZ*skew,0,1,0)
    cv::Mat sampleMat = (Mat_<float>(1,2) << j,i);

What does `<<` mean in these codes? Anyone can educate me a little bit?