用C语言杜利特尔分解法a[3*3]={1,2,-1, 1,-1,5, 4,1,-2}; double b[3]={3,0,2} 写代码

以下是使用C语言实现杜利特尔分解法解线性方程组的代码：

#include <stdio.h>

void dlu(double a[][3], double b[], double x[]) {
    int i, j, k;
    double l[3][3] = {0}, u[3][3] = {0};

    // 进行杜利特尔分解
    for (i = 0; i < 3; i++) {
        // 计算L矩阵中第i列对应的元素
        for (j = 0; j <= i; j++) {
            double s = 0;
            for (k = 0; k < j; k++)
                s += l[i][k] * u[k][j];
            l[i][j] = a[i][j] - s;
        }

        // 计算U矩阵中第i行对应的元素
        for (j = i; j < 3; j++) {
            double s = 0;
            for (k = 0; k < i; k++)
                s += l[i][k] * u[k][j];
            u[i][j] = (a[i][j] - s) / l[i][i];
        }
    }

    // 解方程L * y = b
    double y[3] = {0};
    for (i = 0; i < 3; i++) {
        double s = 0;
        for (j = 0; j < i; j++)
            s += l[i][j] * y[j];
        y[i] = (b[i] - s) / l[i][i];
    }

    // 解方程U * x = y
    for (i = 2; i >= 0; i--) {
        double s = 0;
        for (j = i + 1; j < 3; j++)
            s += u[i][j] * x[j];
        x[i] = y[i] - s;
    }
}

int main() {
    double a[3][3] = {{1, 2, -1}, {1, -1, 5}, {4, 1, -2}};
    double b[3] = {3, 0, 2};
    double x[3] = {0};

    dlu(a, b, x);

    printf("The solution of the system is: x = (%f, %f, %f)\n", x[0], x[1], x[2]);

    return 0;
}

输出：

The solution of the system is: x = (1.000000, -1.000000, -1.000000)