列主元高斯消元法

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define N 4
#define EPS 1e-10

void main()
{
    int A[N][N+1]={{5,2,3,2,-1},{2,4,1,-2,5},{1,-3,4,3,4},{3,2,2,8,-6}},x[N];
    int i,j,k,Pr,t,total;
    for(k=1;k<N;k++)
    {
        Pr=k-1;
        for(i=k;i<N;i++)
        {
            if(abs(A[i][k-1])>abs(A[Pr][k-1]))
            {
                Pr=i;
            }
        }//End For i
        if(abs(A[i][k-1])<EPS)
        {
            printf("主元接近于0，方法失效/n");
            exit(0);
        }
        if(Pr>k-1)
        {
            for(j=k-1;j<N+1;j++)
            {
                t=A[k-1][j];
                A[k-1][j]=A[Pr][j];
                A[Pr][j]=t;
            }//End For j
        } //End if
        for(i=k;i<N;i++)
        {
            t=A[i][k-1]/A[k-1][k-1];
            for(j=k-1;j<N+1;j++)
            {
                A[i][j]=A[i][j]-t*A[k-1][j];
            } //End For j
        } //End For i
    } //End For k
    if(abs(A[N-1][N-1])<EPS)
    {
        printf("主元接近于0，方法失效/n");
        exit(0);
    } //End If
    x[N-1]=A[N-1][N]/A[N-1][N-1];
    for(i=N-2;i>=0;i--)
    {
        total=A[i][N];
        for(j=N-1;j>=i+1;j--)
        {
            total-=A[i][j]*x[j];
        }
        x[i]=total/A[i][i];
    }//End For i
    for(i=0;i<N;i++)
    {
        printf("/n/tx[%d]=%d/n",(i+1),x[i]);
    }//End For i
}