//#define N 500

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <malloc.h>
#include <time.h>
#include <omp.h>

int main(int argc, char *argv[]) {

long i, j, k, l, n;
double begin_to, end_to, c;
double **A, *b, *x;
clock_t begin_t, end_t;

n=atoi(argv[1]);

A=(double**)malloc((n+1)*sizeof(double*));
b=(double*)malloc((n+1)*sizeof(double*));
x=(double*)malloc((n+1)*sizeof(double*));

for(i=1;i<=n;i++)
{
A[i]=(double*)malloc((n+1)*sizeof(double*));
}

n=2;
A[1][1]=1;
A[1][2]=2;
A[2][1]=3;
A[2][2]=4;
b[1]=5;
b[2]=6;

//etap eliminacji zmiennych
for(k=1; k<=n-1; k++)
{
#pragma omp parallel for shared(A, b, k, n) private(i,j,c)
for(i=k+1; i<=n;i++)
{
c=A[i][k]/A[k][k];

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

//postepowanie odwrotne
x[n]=b[n]/A[n][n];

for(k=n-1;k>=1;k--)
{
x[k]=b[k];
for(j=k+1;j<=n;j++)
{
x[k]=x[k]-A[k][j]*x[j];
}
x[k]=x[k]/A[k][k];
}

printf("Rozw.: x[1], x[2] = %f %f\n", x[1], x[2]);

return 0;
}