#include <stdio.h>
#include <stdlib.h>


void afficheMat(float *m, int n){
	float *i;
	/*pour calculer quand une ligne finis*/
	int c;
	for(i=m,c=0;i<m+n*n;i++,c++){
		if(c && !(c%n))
			printf("\n\n");
		else if(c)
			printf("  ");

		printf("%15.7e", *i);
	}
	printf("\n----------------------------------------------------------------------------------------------------------------------------------------------------------------\n");
}


void gaussSansPivot(float *a, float *b, int n){
	float aux, aux2;
	int i;
	for(i=0;i<n-1;i++){
		aux=a[i*n+i];
		int k;
		for(k=i+1;k<n;k++){
			a[i*n + k]/=aux;
		}
		b[i]/=aux;
		for(k=i+1;k<n;k++){
			aux2=a[k*n + i];
			int j;
			for(j=i+1;j<n;j++)
				a[k*n+j] -= aux2 * a[i*n+j];
			b[k]-=aux2*b[i];
		}
	}

	b[n-1] /= a[n*n -1];

	for(i=n-2; i>=0;i--){
		aux=b[i];
		int k;
		for(k=i+1;k<n;k++)
			aux-= a[i*n + k] * b[k];
		b[i]=aux;
	}
}

void main() {
    //int n;
    //printf("n: \n");
    //scanf("%d", &n);
 	int i;
    float b[4]={11.11,10.67,12.41,10.52};
    float a[16]={2.5,1.5,1.7,2.5,1.7,1.8,2.2,1.8,2.0,1.2,2.5,3.0,2.1,1.2,2.2,1.5};
    gaussSansPivot(a,b,4);
    for(i=0;i<4;i++) printf("%15.7e",b[i]);
    printf("\n");
}