Adds new gaussian elimination algorithm

Author: Jason Boutte

lab3/gauss.c

@@ -1,10 +1,13 @@
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #define MAX_RAND 1.0e2 //1.0e6
 
-void gen_augmented_matrix(double **matrix, int n);
+void swap_pivot(double **matrix, int col, int n);
+void generate_aug_matrix(double **matrix, int n);
+void print_aug_matrix(double **matrix, int n);
 void print_usage(char *prog);
 
 int main(int argc, char **argv) {
@@ -14,21 +17,47 @@ int main(int argc, char **argv) {
     exit(1);
   }
 
-  int n, i, j, k;
+  int n;
+  int i, j, k;
+  double factor;
+  double interm;
+  double *result;
   double **matrix;
 
   srand(time(NULL));
   srand48(time(NULL));
 
   n = atoi(argv[1]);
 
+  result = malloc(n * sizeof(double));
+
+  memset(result, 0, n * sizeof(double));
+
   matrix = malloc(n * sizeof(double));
 
   for (i = 0; i < n; ++i) {
     matrix[i] = malloc((n + 1) * sizeof(double));
   }
 
-  gen_augmented_matrix(matrix, n);
+  generate_aug_matrix(matrix, n);
+
+  for (i = 0; i < n; ++i) {
+    swap_pivot(matrix, i, n);
+
+    print_aug_matrix(matrix, n);
+
+    for (j = i + 1; j < n; ++j) {
+      factor = matrix[j][i] / matrix[i][i];
+
+      printf("Factor %f\n", factor);
+
+      for (k = 0; k < n + 1; ++k) {
+        interm = factor * matrix[i][k];
+
+        matrix[j][k] -= interm;
+      }
+    }
+  }
 
   for (i = 0; i < n; ++i) {
     free(matrix[i]);
@@ -39,7 +68,31 @@ int main(int argc, char **argv) {
   return 0;
 }
 
-void gen_augmented_matrix(double **matrix, int n) {
+void swap_pivot(double **matrix, int col, int n) {
+  int i;
+  int pivot;
+  double max;
+  double value;
+  double *temp;
+
+  for (i = col; i < n; ++i) {
+    value = fabs(matrix[i][col]);
+
+    if (value > max) {
+      pivot = i;
+
+      max = value;
+    } 
+  }
+
+  temp = matrix[pivot];
+
+  matrix[pivot] = matrix[col];
+
+  matrix[col] = temp;
+}
+
+void generate_aug_matrix(double **matrix, int n) {
   int i, j;
 
   for (i = 0; i < n; ++i) {
@@ -53,6 +106,22 @@ void gen_augmented_matrix(double **matrix, int n) {
   }
 }
 
+void print_aug_matrix(double **matrix, int n) {
+  int i, j;
+
+  printf("\n");
+
+  for (i = 0; i < n; ++i) {
+    for (j = 0; j < n; ++j) {
+      printf("%.2f\t", matrix[i][j]);
+    }
+   
+    printf("\tx%i\t%.2f\n", i+1, matrix[i][n]);
+  }
+
+  printf("\n");
+}
+
 void print_usage(char *prog) {
   printf("%s n threads\n", prog); 
   printf("n - Size of the matrix\n");