This is not a matrix rotation operator, but it just perform an axis offset of tx and ty respectively for X and Y. The 2D rotation operator has the sine and cosine functions there.
If you performs the above matricial operation, it would result in:
Code:
x' = x + t[SUB]x[/SUB]
y' = y + t[SUB]y[/SUB]
It is somewhat intuitive to deduce that this equation describes the shift of the original <x,y> coordinates to a new position <(x+tx),(y+ty)>, invariant is scale or orientation, which reinforce the statement that it is not a "2D rotation" operation as you supposed in the 1st post of this thread.