Difference between cv::Mat::t () and cv::transpose()

Question

What is the difference in opencv between these two transposes?

Using cv::Mat::t():

cv::Mat a;
a = a.t();

Using cv::transpose():

cv::Mat a;
cv::transpose(a,a);

I'm interested in particular about efficiency.

Answer 1

There's no difference. Here's the code for cv::Mat::t() from opencv/modules/core/src/matop.cpp:

MatExpr MatExpr::t() const
{
    MatExpr e;
    op->transpose(*this, e);
    return e;
}

So cv::Mat::t() just calls cv::transpose().