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

  for (int m=1; m<=20; m++) {
    // Matrix size
    int n = m*100;

    // Allocation
    double **a, **b, **c, *x, *y, *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;

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

    x = new double[n];
    y = 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-matrix product
    for (i=0; i<n; i++) {
      for (j=0; j<n; j++) {
	c[i][j] = 0.0;
	for (k=0; k<n; k++)
	  c[i][j] += a[i][k] * b[k][j];
      }
    }

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