#include<stdio.h>
#include<math.h>
#define N 6
void Jacobi(float a[][6], float b[], int n, float x0[], float delta, int maxn)//雅克比迭代法
{
    int k, i, j;
    float sum=0, err=0, x1[6]={0,0,0,0,0,0};
    for (k = 0; k < maxn; k++)
    {
        for (i = 0; i<n; i++)
        {
            for (j = 0; j<i; i++)
                sum += a[i][j] * x0[j];
            for (j = i + 1; j<n; j++)
                sum += a[i][j] * x0[j];

            x1[i] = (b[i] - sum) / a[i][i];
            err += (x1[i] - x0[i])*(x1[i] - x0[i]);
            sum = 0;
        }
        for(i=0;i<N;i++)
            x0[i]=x1[i];
        err = sqrt(err);
        if (err < delta)
            break;
    }
    if (k >= maxn-1)
        printf("此次迭代发散，结果作废");
    else
    {
        printf("经过%d次雅克比迭代得到以下解向量\n", k+1);
        for (i = 0; i<N; i++)
            printf("%3.4f", x0[i]);
    }
}


void GaussSeidel(float a[][6], float b[], int n, float x0[], float delta, int maxn)//高斯-赛德尔迭代
{
    int k, i, j;
    float sum=0, err=0, Temporary=0;
    for (k = 1; k <= maxn; k++)
    {
        for (i = 0; i<n; i++)
        {
            for (j = 0; j<i; i++)
            {
                sum += a[i][j] * x0[j];
            }
            for (j = i + 1; j<n; j++)
            {
                sum += a[i][j] * x0[j];
            }

            Temporary = (b[i] - sum) / a[i][i];
            err += (Temporary - x0[i])*(Temporary - x0[i]);

            x0[i] = Temporary;
            sum = 0;
        }
        err = sqrt(err);
        if (err < delta)
            break;
    }
    if (k == maxn)
        printf("此次迭代发散，结果作废");
    else
    {
        printf("经过%d次高斯-赛德尔迭代得到以下解向量\n", k);
        for (i = 0; i<N; i++)
            printf("%3.4f", x0[i]);
    }
}



void main()
{
    float A[N][N], x0[N]={0,0,0,0,0,0}, b[N], delta=0.0001;
    int i, j, k,maxn, n=6;

    FILE *fp=fopen("inA.txt","r"),*fq=fopen("inb.txt","r");

    if(!fp)
    {
        printf("file inA.txt can't open\n");
    }
    if(!fq)
    {
        printf("file inb.txt can't open\n");
    }
    while(!feof(fp))
    {
        for (i = 0; i < N; i++)
            for (j = 0; j < N; j++)
                fscanf(fp,"%f", &A[i][j]);
        printf("读入的A矩阵如下：\n");
        for (i = 0; i < N; i++)
        {
            for (j = 0; j < N; j++)
                printf("%8.1f", A[i][j]);
            printf("\n");
        }
        printf("\n\n");
    }

    while(!feof(fq))
    {
        for(i=0;i<N;i++)
            fscanf(fq,"%f", &b[i]);
        printf("读入的b系数矩阵如下：\n");
        for (i = 0; i < N; i++)
            printf("%8.1f", b[i]);
        printf("\n");
    }

    printf("请输入迭代最大次数\n");
    scanf("%d", &maxn);

    printf("请选择算法：\n1.雅克比迭代\n2.高斯赛德尔迭代\n");
    scanf("%d",&k);
    if(k==1)
        Jacobi(A, b, n, x0, delta, maxn);//调用雅克比迭代法
    else
        GaussSeidel(A, b, n, x0, delta, maxn);//调用高斯赛德尔迭代法

}

不能附TXT，就附的压缩文件了

我自己推断可能是红色部分粗问题了，但就是找不出；望大侠指点

void Jacobi(float a[][6], float b[], int n, float x0[], float delta, int maxn)//雅克比迭代法
{
    int k, i, j;
    float sum=0, err=0, x1[6]={0,0,0,0,0,0};
    for (k = 0; k < maxn; k++)
    {
        for (i = 0; i<n; i++)
        {
            for (j = 0; j<i; i++)
                sum += a[i][j] * x0[j];
            for (j = i + 1; j<n; j++)
                sum += a[i][j] * x0[j];

            x1[i] = (b[i] - sum) / a[i][i];
            err += (x1[i] - x0[i])*(x1[i] - x0[i]);
            sum = 0;
        }
        for(i=0;i<N;i++)
            x0[i]=x1[i];
        err = sqrt(err);
        if (err < delta)
            break;
    }
    if (k >= maxn-1)
        printf("此次迭代发散，结果作废");
    else
    {
        printf("经过%d次雅克比迭代得到以下解向量\n", k+1);
        for (i = 0; i<N; i++)
            printf("%3.4f", x0[i]);
    }
}

迭代求方程组近似解得

万分感谢啊，我调了半天啊，都要哭了，竟然犯这种错误，醉了