Zeile zuerst, Spalte später
uij
i=Zeile
j=Spalte
(a11a21a12a22)⋅(b11b21b12b22)=(a11⋅b11+a12⋅b21a21⋅b11+a22⋅b21a11⋅b21+a12⋅b22a21⋅b21+a22⋅b22)
(a11a21a12a22)+(b11b21b12b22)=(a11+b11a21+b21a12+b12a22+b22)
(a11a21a12a22)−(b11b21b12b22)=(a11−b11a21−b21a12−b12a22−b22)