#include <stdio.h>
#include <time.h>
int main()
{
  int i, j, k;
  printf("Matrix size    Elapsed time [sec] \n");

  for (int m=1; m<=15; m++) {
    // Matrix size
    int n = m*1000;

    // Allocation
    double **a, **b, *x, *y, *z, *dum;
    dum = new double[n*n];
    a = new double*[n];
    for (i=0; i<n; i++)
      a[i] = dum + i*n;

    dum = new double[n*n];
    b = new double*[n];
    for (i=0; i<n; i++)
      b[i] = dum + i*n;






    x = new double[n];
    y = new double[n];
    z = new double[n];

    // Initialization
    for (i=0; i<n; i++) {
      for (j=0; j<n; j++) {
	a[i][j] = 1.0;
	b[i][j] = 2.0;
      }
      x[i] = 1.0;
    }

    // Start time
    clock_t time0 = clock();

    // Main calculation 1: matrix-vector product
    for (i=0; i<n; i++) {
      z[i] = 0.0;
      for (k=0; k<n; k++)
	z[i] += b[i][k] * x[k];
    }



    // Main calculation 2: matrix-vector product
    for (i=0; i<n; i++) {
      y[i] = 0.0;
      for (k=0; k<n; k++)
	y[i] += a[i][k] * z[k];
    }

    // Finish time
    clock_t time1 = clock();

    // Output time
    double eTime = (double)(time1-time0)/CLOCKS_PER_SEC;
    printf("%11d %15.7f\n",n, eTime);

    // Deallocation
    delete a[0]; delete b[0];
    delete[] a; delete[] b;
    delete[] x; delete[] y; delete[] z;
  }
  return 0;
}