opencv - opencv2协方差矩阵奇怪的结果

Question

以下代码给出了不一致的协方差矩阵大小。

cv::Mat A = (cv::Mat_<float>(3,2) << -1, 1, -2, 3, 4, 0);
cv::Mat covar1, covar2, covar3, covar4, mean;
calcCovarMatrix(A, covar1, mean, CV_COVAR_NORMAL | CV_COVAR_ROWS);
calcCovarMatrix(A, covar2, mean, CV_COVAR_SCRAMBLED | CV_COVAR_ROWS);
calcCovarMatrix(A, covar3, mean, CV_COVAR_NORMAL | CV_COVAR_COLS);
calcCovarMatrix(A, covar4, mean, CV_COVAR_SCRAMBLED | CV_COVAR_COLS);

std::cout << "size: " << covar1.size() << "\n";
std::cout << "size: " << covar2.size() << "\n";
std::cout << "size: " << covar3.size() << "\n";
std::cout << "size: " << covar4.size() << "\n";

covar1和 covar2应该具有相同的大小，因为它们都描述了行的协方差，而 covar3和 covar4应该具有相同的大小，因为它们都描述了列的协方差。但是，输出为:

size: [2 x 2]
size: [3 x 3]
size: [3 x 3]
size: [2 x 2]

Answer 1

calcCovarMatrix() docs，具体说，当使用CV_COVAR_SCRAMBLED时，“协方差矩阵将为nsamples x nsamples。”