Lista 3

lista3/ex4.c

+#include <stdio.h>
+#include <stdlib.h>
+
+void eliminaGauss(double **a, int n, double *b) {
+    for(int k=0; k < n; ++k) {
+        for(int i = k+1; i < n; ++i) {
+            double m = a[i][k]/a[k][k];
+            a[i][k] = 0.0f;
+            for(int j=k+1; j < n; ++j) {
+                a[i][j] -= a[k][j] * m;
+            }
+            b[i] -= b[k] * m;
+        }
+    }
+}
+
+void eliminaGaussPivo(double **a, int n, double *b) {
+    for(int k=0; k < n; ++k) {
+        int max = k;
+        for(int i = k+1; i < n; ++i) {
+            max = (a[i][k] > a[max][k]) ? i : max;
+        }
+        if(max != k) trocaLinha(a, n, b, max, k);
+        for(int i = k+1; i < n; ++i) {
+            double m = a[i][k]/a[k][k];
+            a[i][k] = 0.0f;
+            for(int j=k+1; j < n; ++j) {
+                a[i][j] -= a[k][j] * m;
+            }
+            b[i] -= b[k] * m;
+        }
+    }
+}
+
+void trocaLinha(double **a, int n, double *b, int l1, int l2) {
+    double temp;
+    temp = b[l2];
+    b[l2] = b[l1];
+    b[l1] = temp;
+    for(int i = 0; i < n; ++i) {
+        temp = a[l1][i];
+        a[l1][i] = a[l2][i];
+        a[l2][i] = temp;
+    }
+}
+
+void retro(double **a, int n, double *b, double *x) {
+    x[n-1] = b[n-1]/a[n-1][n-1];
+    for(int i = n-2; i >= 0; --i) {
+        double soma=0.0f;
+        for(int j = n-1; j > i; --j) {
+            soma += a[i][j]*x[j];
+        }
+        x[i] = (b[i] - soma)/a[i][i];
+    }
+    
+}
+
+int main() {
+    double **a, **A, *b, *B, *x;
+    int n;
+
+    printf("Ordem da matriz: \n");
+    scanf("%d", &n);
+
+    a = malloc(n*sizeof(double*));
+    A = malloc(n*sizeof(double*));
+    b = malloc(n*sizeof(double));
+    B = malloc(n*sizeof(double));
+    x = malloc(n*sizeof(double));
+    for(int i=0; i < n; ++i) {
+        a[i] = malloc(n*sizeof(double));
+        A[i] = malloc(n*sizeof(double));
+    }
+
+    for(int i=0; i < n; ++i) {
+        for(int j=0; j < n; ++j) {
+            printf("(%d, %d)\t", i, j);
+            scanf("%lf", &a[i][j]);
+            A[i][j] = a[i][j];
+        }
+    }
+
+    printf("B\n");
+    for(int i=0; i < n; ++i) {
+        printf("b[%d]", i);
+        scanf("%lf", &b[i]);
+        B[i] = b[i];
+    }
+
+    eliminaGauss(a, n, b);
+    retro(a, n, b, x);
+    printf("Resposta: \n");
+    for(int i = 0; i < n; ++i) {
+        printf("%.4lf\n", x[i]);
+    }
+
+    eliminaGaussPivo(A, n, B);
+    retro(A, n, B, x);
+    printf("Pivo: \n");
+    for(int i = 0; i < n; ++i) {
+        printf("%.4lf\n", x[i]);
+    }
+
+    return 0;
+}
+