what is the current state of the art in fast and parallel matrix in-place transposition?
I would be very happy, if I could be given some pseudocode for this problem. As far as I could find papers, they do not include very detailed descriptions.
PS: Of course, we do not restrict to square matrices, but rather arbitrary rectangular matrices. Their memory layout is usually a linear sequence of entries in the memory (say, as in C) and it is a highly non-trivial task to convert this data block in-place/in-situ to the sequence that corresponds to the transposed matrix.
Some information can be found in this wikipedia article, whose references I did not find to be very helpful though: Wikipedia Entry.