For example, I would like to extract each 2 × 2 submatrix in a 3 × 3 matrix, converting them to column vector, then obtaining a new matrix. Like this:
1…2…3./././././././././1…2…4…5
4…5…6…------->…2…3…5…6
7…8…9./././././././././4…5…7…8
./././././././././././././././/5…6…8…9
and how to effectively implement the inv-process.
Thank you for your attention and answer.