Exemple de sortie écran :
 Ab
 +0.0000e+00 +0.0000e+00 +0.0000e+00 +1.0000e+00 +4.0500e-03 -8.0479e-04 
 +1.0000e+00 +0.0000e+00 +0.0000e+00 +0.0000e+00 -5.6074e-03 +6.9059e-03 
 +0.0000e+00 +1.0000e+00 +0.0000e+00 +0.0000e+00 +1.0105e-02 +4.9401e-03 
 -0.0000e+00 -0.0000e+00 +1.0000e+00 -0.0000e+00 +3.5346e-03 -6.3411e-03 
 -1.4045e-02 -1.7865e-03 
 +2.3002e-03 +4.6525e-03 
 +7.0962e-03 +1.0533e-02 
 -1.2066e-02 +6.2204e-03 
 Press return to continue. 
/* --------- DEBUG 1 ---------- */
 Ab : pivot[1][1] = 0.000000 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Ab
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Press return to continue. 
/* --------- DEBUG 1 ---------- */
 Ab : pivot[2][1] = 1.000000 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Ab
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Press return to continue. 
/* --------- DEBUG 1 ---------- */
 Ab : pivot[2][2] = 0.000000 
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Ab
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Press return to continue. 
/* --------- DEBUG 1 ---------- */
 Ab : pivot[3][2] = 1.000000 
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Ab
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Press return to continue. 
/* --------- DEBUG 1 ---------- */
 Ab : pivot[3][3] = 0.000000 
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Ab
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Press return to continue. 
/* --------- DEBUG 1 ---------- */
 Ab : pivot[4][3] = 1.000000 
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 Ab
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 Press return to continue. 
/* --------- DEBUG 1 ---------- */
 Ab : pivot[4][4] = 1.000000 
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 Ab
 +1.0000 +0.0000 +0.0000 +0.0000 -0.0056 +0.0069 +0.0023 +0.0047 
 +0.0000 +1.0000 +0.0000 +0.0000 +0.0101 +0.0049 +0.0071 +0.0105 
 -0.0000 -0.0000 +1.0000 -0.0000 +0.0035 -0.0063 -0.0121 +0.0062 
 +0.0000 +0.0000 +0.0000 +1.0000 +0.0041 -0.0008 -0.0140 -0.0018 
 Press return to continue. 
 Copy/Past into the octave window.
format short e
 A=[
-65,+56,-33,+46;
+68,+28,-73,+88;
-29,+12,-15,-57;
+50,+20,+76,-47]
 inv(A)
 -5.6074e-03 +6.9059e-03 +2.3002e-03 +4.6525e-03 
 +1.0105e-02 +4.9401e-03 +7.0962e-03 +1.0533e-02 
 +3.5346e-03 -6.3411e-03 -1.2066e-02 +6.2204e-03 
 +4.0500e-03 -8.0479e-04 -1.4045e-02 -1.7865e-03 
 A * inv(A)
 +1.0000 -0.0000 +0.0000 +0.0000 
 +0.0000 +1.0000 +0.0000 +0.0000 
 +0.0000 +0.0000 +1.0000 -0.0000 
 +0.0000 +0.0000 +0.0000 +1.0000 
 Press return to continue
 Press X to stop

Mathc matrices/a03b
Copier la bibliothèque dans votre répertoire de travail :
Exemple pour tester la bibliothèque :

Mathc matrices/a03c
Étude du code
Étude de quelques fonctions :

Mathc matrices/a03d
Application
Installer et compiler ce fichier dans votre répertoire de travail.
/* Save as : c00a.c */
int main(void)
nb_Z a;
 do{ 
 clrscrn();
 a = i_Z( 1, -3);
 printf(" a = "); p_Z(a,S3,P0,S3,P0); printf("\n\n");
 printf(" Re(a) = %8.1f \n",Re_Z(a));
 printf(" Im(a) = %8.1f \n\n\n",Im_Z(a));
 a = rE_Z(9999,1E-4);
 printf(" a = "); p_Z(a,S3,P4,S3,P4); printf("\n\n");
 printf(" Re(a) = %8.4f \n",Re_Z(a));
 printf(" Im(a) = %8.4f \n\n\n",Im_Z(a));
 } while(stop_w()); 
 return 0;
/* ------------------------------------ */
Nous allons cette fois imprimer les parties réelles et imaginaires des nombres complexes. 
Exemple de sortie écran : 
 a = +1 -3i 
 Re(a) = 1.0 
 Im(a) = -3.0 
 a = +0.9830-0.0964i 
 Re(a) = 0.9830 
 Im(a) = -0.0964 
 Press return to continue
 Press X return to stop

Les opérations bit à bit/Manipulations sur les puissances de deux

Mathc matrices/a13
Bibliothèque
---- 
---- 
---- 
---- 
----

Mathc matrices/a14
Bibliothèque
---- 
---- 
---- 
----

Mathc matrices/a15
Bibliothèque
Dans cet algorithme le pivot choisi est la plus grande valeur absolue qui se trouve dans la matrice A. Pour cela on fait des échanges de lignes et de colonnes. Attention on ne touche pas à b.
Copier la bibliothèque dans votre répertoire de travail avec les fichiers des parties précédentes :
Exemple pour tester la bibliothèque :

Mathc matrices/h15a
Bibliothèque
Installer ce fichier dans votre répertoire de travail.
/* Save as : v_a.h */
/* Standard file */
/* Usefull */
/* Create */
/* Copy */
/* Print */
/* Basic operation */
/* Determinant */
/* Gauss Jordan */
/* Rand */
/* ------------------------------------ */
 Déclaration des fichiers h.