# Product of matrices; MAPLE giving a strange answer

Either my brain is seriously fried up right now or the computer is wrong.

If I have a matrix $\begin{bmatrix} 4 & -2\\ 2 & -1 \\ 0 & 0 \end{bmatrix}$ multiply by its transpose $\begin{bmatrix} 4 &2 &0 \\ -2&-1 &0 \end{bmatrix}$, I should get a $3 \times 3$ $\begin{bmatrix} 20 &10 &0 \\ 10 &5 &0 \\ 0&0 &0 \end{bmatrix}$

For some reason Maple is giving me a $2 \times 2$ $\begin{bmatrix} 20 &10 \\ 10 &5 \\ \end{bmatrix}$

Why did they delete the last row and column of 0s? You can't do that

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This is maybe just a Maple convention: you should change your title to indicate that it's something happening in Maple. Also, don't assume your questions are too dumb for this this forum :) It's not like MathOverflow... – you Apr 10 '12 at 2:35
Are you doing $A A^T$ or $A^T A$? – lhf Apr 10 '12 at 2:46
Never mind, I am the one who is wrong...I multiplied it the other way – Hed Apr 10 '12 at 2:46
Can you edit the question so that its title is useful in some way? – Mariano Suárez-Alvarez Apr 10 '12 at 2:52
Note, though, that if you multiplied them the other way, you should have gotten $$\left(\begin{array}{rr}20&-10\\-10&5\end{array}\right)$$and not what you say you got. – Arturo Magidin Apr 10 '12 at 3:06