Escalonamento (Eliminação Gaussiana)

#include <stdio.h>
#include <math.h>

#define N 4

int main(void)
{
    double A[N][N]={{2,1,4,1},{3,4,-1,-1},{1,-4,1,5},{2,-2,1,3}}, b[N]={-4,3,9,7};
    int i,j,k;

    for (i=0;i<N;i++)
    {
        for (j=i+1;j<N;j++)
        {
            double c=A[j][i]/A[i][i];

            for (k=i;k<N;k++)
            {
                A[j][k]=A[j][k] - c*A[i][k];
            }

            b[j]=b[j]-c*b[i];
        }
    }

    for (i=0;i<N;i++)
    {
        for (j=0;j<N;j++)
        {
            printf("%8.3lf",A[i][j]);

            if (j==(N-1))
                printf("\n");
            else
                printf(" ");
        }
    }

    return 0;
}