(%i2) "Cornelsen, S. 207, Übung 2"$

(%i3) A1: matrix([2.0,3.0,-1.0],[4.0,-2.0,1.0]);
                             [ 2.0   3.0   - 1.0 ]
(%o3)                        [                   ]
                             [ 4.0  - 2.0   1.0  ]

(%i4) B1: matrix([1.0,2.0,-2.0,3.0],[-1.0,3.0,2.0,0.0],[2.0,0.0,4.0,1.0]);
                          [  1.0   2.0  - 2.0  3.0 ]
                          [                        ]
(%o4)                     [ - 1.0  3.0   2.0   0.0 ]
                          [                        ]
                          [  2.0   0.0   4.0   1.0 ]

(%i5) A1 . B1;
                         [ - 3.0  13.0  - 2.0  5.0  ]
(%o5)                    [                          ]
                         [  8.0   2.0   - 8.0  13.0 ]

(%i6) B1 . A1;

MULTIPLYMATRICES: attempt to multiply nonconformable matrices.
 -- an error. Folgerung?

(%i7) A2: matrix([1.0,2.0,0.0],[2.0,3.0,0.0],[3.0,4.0,1.0]);
                               [ 1.0  2.0  0.0 ]
                               [               ]
(%o7)                          [ 2.0  3.0  0.0 ]
                               [               ]
                               [ 3.0  4.0  1.0 ]

(%i8) B2: matrix([-3.0,2.0,0.0],[2.0,-1.0,0.0],[1.0,-2.0,1.0]);
                             [ - 3.0   2.0   0.0 ]
                             [                   ]
(%o8)                        [  2.0   - 1.0  0.0 ]
                             [                   ]
                             [  1.0   - 2.0  1.0 ]

(%i9) A2 . B2;
                               [ 1.0  0.0  0.0 ]
                               [               ]
(%o9)                          [ 0.0  1.0  0.0 ]
                               [               ]
                               [ 0.0  0.0  1.0 ]

(%i10) B2 . A2;
                               [ 1.0  0.0  0.0 ]
                               [               ]
(%o10)                         [ 0.0  1.0  0.0 ]
                               [               ]
                               [ 0.0  0.0  1.0 ]

(%i11) "Folgerung aus A2 . B2 = E = B2 . A2 ?"$

(%i12) "Cornelsen, S. 209, Nr. 8"$

(%i13) "Antwort: 4 x Falsch (!)"$

(%i14) "Cornelsen, S. 209, Nr. 7"$

Anleitung: Stelle eine 'Gewinnmatrix' als 4x1-Matrix auf,
und ermittle den Gewinn für jede Filiale durch Matrizenmultiplikation.
Beachte: Als Ergebnis muss eine Zahl herauskommen! (Warum?)
Ergebnis:  1: 1490 EUR; 2: 1520 EUR; 3: 480 EUR; 4: 2010 EUR