Lesson 9。

09/Exercise02.c

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+#include <stdio.h>
+#include <stdbool.h>
+
+double matA[4][4] = {
+    {1.1161, 0.1254, 0.1397, 0.1490},
+    {0.1582, 1.1675, 0.1768, 0.1871},
+    {0.2368, 0.2471, 0.2568, 1.2671},
+    {0.1968, 0.2071, 1.2168 ,0.2271}
+};
+
+double matB[4] = {
+    1.5471, 1.6471, 1.8471, 1.7571
+};
+
+void rowManipulation(int originRow, double coefficent, int rowBeingAdded) {
+    int col = 0;
+    for (col = 0; col < 4; col++) {
+        matA[rowBeingAdded][col] += matA[originRow][col] * coefficent;
+    }
+    matB[rowBeingAdded] += matB[originRow] * coefficent;
+}
+
+void timesOfRow(int rowCount, double time) {
+    int col = 0;
+    for (col = 0; col < 4; col++) {
+        matA[rowCount][col] *= time;
+    }
+    matB[rowCount] *= time;
+}
+
+int findNoneZeroItem(int startRowIndex, int columnIndex) {
+    bool found = false;
+    int pos = startRowIndex;
+    for (pos = startRowIndex; pos < 4; pos++) {
+        if (matA[pos][columnIndex] != 0) {
+            return pos;
+        }
+    }
+    return -1;
+}
+
+void swapRow(int firstRowIndex, int secondRowIndex) {
+    double temp = 0;
+    int i = 0;
+    for (i = 0; i < 4; i++) {
+        temp = matA[firstRowIndex][i];
+        matA[firstRowIndex][i] = matA[secondRowIndex][i];
+        matA[secondRowIndex][i] = temp;
+    }
+    temp = matB[firstRowIndex];
+    matB[firstRowIndex] = matB[secondRowIndex];
+    matB[secondRowIndex] = temp;
+}
+
+void printOut() {
+    int i = 0, j = 0;
+    for (i = 0; i < 4; i++) {
+        for (j = 0; j < 4; j++) {
+            printf("%lf\t", matA[i][j]);
+        }
+        printf("%lf", matB[i]);
+        printf("\n");
+    }
+}
+
+int main() {
+    int x[4] = {0};
+    int column = 0, row = 0;
+    int tempRow = 0;
+    int noneZeroRow = 0;
+    for (column = 0; column < 4; column++) {
+        noneZeroRow = findNoneZeroItem(row, column);
+        if (noneZeroRow == -1) {
+            continue;
+        }
+        else {
+            swapRow(row, noneZeroRow);
+            timesOfRow(row, 1.0/matA[row][column]);
+            for (tempRow = 0; tempRow < 4; tempRow++) {
+                if (tempRow != row)
+                rowManipulation(row, -matA[tempRow][column], tempRow);
+            }
+            row++;
+        }
+        
+    }
+    for (row = 0; row < 4; row++) {
+        printf("x(%d) = %lf\n", row+1, matB[row]);
+    }
+    return 0;
+}