Talk:In-place matrix transposition

Question

The formula in "Properties of the transposition" is wrong! Here is my counter example. Consider the following matrix:

$\mathbf {A} ={\begin{bmatrix}A&B&C&D&E\\F&G&H&I&J\\K&L&M&N&O\\P&Q&R&S&T\\U&V&W&X&Y\end{bmatrix}}$ $\mathbf {A'} ={\begin{bmatrix}A&F&K&P&U\\B&G&L&Q&V\\C&H&M&R&W\\D&I&N&S&X\\E&J&O&T&Y\end{bmatrix}}$

Now lets use the formula to find out where 'N' from the original should go in the transposed matrix

$N=A(13)=A'((5*13)mod((5*5)-1))$

$=A'(65mod15)$

$=A'(5)=B$

$N!=B$

So what the heck is going on here? —Preceding unsigned comment added by Jblaufeld (talk • contribs)

(5*5)-1 is not 15, it's 24. (65 mod 24) is 17, which is exactly the correct index position of 'N' in the transposed matrix. Shreevatsa (talk) 16:56, 14 April 2009 (UTC)

Wow, I'm an idiot...thanks!jblaufeld

Cycle Permutation

The description of the permutation is wrong, i think. It says the permutation is

(0), (1 2 4), (3 6 5), (7)

But it looks to me the permutation is

(0), (1 4 2), (3 5 6), (7)

Or am i missing something? Also, the explanation following that cycle list is deeply confusing to me.