1 /**

     2  * $Id: gauss.c,v 1.1.1.1 2008-04-28 17:32:53 mbroeker Exp $

     3  * $Source: /development/c/gauss/gauss.c,v $

     4  *

     5  */

     6 

     7 #define VERSION 0.8

     8 

     9 #ifndef VERBOSE

    10 #define VERBOSE 1

    11 #endif

    12 #ifndef ZEROASSUMPTION

    13 #define ZEROASSUMPTION 1E-3     /* 0.001 = 0.0 */

    14 #endif

    15 

    16 #include <stdio.h>

    17 #include <stdlib.h>

    18 

    19 void ausgabe (float **A, int MAXX, int MAXY)

    20 {

    21     int n, k;

    22 

    23     for (k = 0; k < MAXY; k++) {

    24         for (n = 0; n < MAXX - 1; n++) {

    25             if ((A[k][n] < ZEROASSUMPTION) && (A[k][n] > -ZEROASSUMPTION))

    26                 A[k][n] = 0.0;

    27             printf ("%8.2f ", A[k][n]);

    28         }

    29         printf ("=%8.2f\n", A[k][n]);

    30     }

    31 }

    32 

    33 void gauss (float **A, int MAXX, int MAXY)

    34 {

    35     int i, j, k, n;

    36     float h;

    37 

    38     i = 0;

    39     for (j = 0; j < MAXY; j++) {

    40         for (k = j + 1; k < MAXY; k++) {

    41             if (A[k][i] != 0)

    42                 h = A[j][i] / A[k][i];

    43             else

    44                 continue;

    45 

    46             for (n = 0; n < MAXX; n++) {

    47                 A[k][n] *= -h;

    48                 A[k][n] += A[j][n];

    49             }

    50         }

    51         i++;

    52     }

    53 

    54 #ifdef PUPILS

    55     printf ("\n");

    56     ausgabe (A, MAXX, MAXY);

    57     printf ("\n");

    58 #endif

    59 

    60     i--;                        /* i = (MAXX-1)-1; */

    61 

    62     for (j = MAXY - 1; j > -1; j--) {

    63         for (k = j - 1; k > -1; k--) {

    64             h = A[j][i] / A[k][i];

    65             for (n = MAXX - 1; n > k - 1; n--) {

    66                 A[k][n] *= -h;

    67                 A[k][n] += (A[j][n]);

    68                 if (A[j][i] == 0.0) {

    69                     printf ("Divison by Zero\n");

    70                     exit (-1);

    71                 }

    72                 A[j][n] /= (A[j][i]);

    73             }

    74         }

    75         i--;

    76     }

    77 

    78     if ((h = A[0][0]) == 0.0) {

    79         printf ("Division by Zero\n");

    80         exit (-1);

    81     }

    82     /*h=A[0][0];*/

    83     A[0][0] /= h;

    84     A[0][MAXX - 1] /= h;

    85 }

    86 

    87 int main (int argc, char **argv)

    88 {

    89     int i, k;

    90     int MAXX, MAXY;

    91     float value;

    92 

    93     float **A;

    94 

    95     if (argc != 2) {

    96         printf ("Benutzung: %s UNBEKANNTE\n", argv[0]);

    97         printf ("Berechnet ein lineares Gleichungssystem mit n UNBEKANNTEN und n Zeilen ( nxn ).\n");

    98         printf ("Praktische Beispiele stehen in der README Datei.\n");

    99         return EXIT_SUCCESS;

   100     }

   101 

   102     MAXY = atoi (argv[1]);

   103     MAXX = MAXY + 1;

   104 

   105     if ((A = calloc (MAXY, sizeof (float *))) == NULL) {

   106         printf ("Nicht genug Speicher verfuegbar\n");

   107         return EXIT_SUCCESS;

   108     }

   109 

   110     for (i = 0; i < MAXY; i++) {

   111         if ((A[i] = calloc (MAXX, sizeof (float))) == NULL) {

   112             printf ("Nicht genug Speicher verfuegbar\n");

   113             for (k = 0; k < i; k++)

   114                 free (A[k]);

   115             free (A);

   116 

   117             return EXIT_SUCCESS;

   118         }

   119     }

   120 

   121     for (k = 0; k < MAXY; k++) {

   122         printf ("Spalte %d: ", k);

   123         for (i = 0; i < MAXX; i++) {

   124             if (scanf ("%f", &value) < 1) {

   125                 printf ("READ ERROR\n");

   126                 return EXIT_FAILURE;

   127             }

   128             A[k][i] = value;

   129         }

   130     }

   131 

   132     if (VERBOSE) {

   133         printf ("\n");

   134         ausgabe (A, MAXX, MAXY);

   135     }

   136 

   137     gauss (A, MAXX, MAXY);

   138 

   139     printf ("\nLoesung des GL-Systems( %d x %d )\n\n", MAXX - 1, MAXY);

   140     for (i = 0; i < MAXY; i++)

   141         printf ("a[%2d] = %8.2f\n", i, A[i][MAXX - 1]);

   142 

   143     for (i = 0; i < MAXY; i++)

   144         if (A[i] != NULL)

   145             free (A[i]);

   146     if (A != NULL)

   147         free (A);

   148 

   149     return EXIT_SUCCESS;

   150 }