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

#define N 2048

double A[N][N], B[N][N], C[N][N];

double get_dtime(void){
  struct timeval tv;
  gettimeofday(&tv, NULL);
  return ((double)(tv.tv_sec) + (double)(tv.tv_usec) * 0.001 * 0.001);
}

int main()
{
  int i, j, k, count = 0;
  double sum, d1, d2;
  
  while(count < 12){
    /* 行列の初期化と要素の追加 */
      for(i = 0; i < N; i++) {
	for(j = 0; j < N; j++){
	  if(i != j){
	    A[i][j] = 0.0;
	    B[i][j] = 0.0;
	  }
	  else{
	    A[i][j] = 10.0;
	    B[i][j] = 0.1;
	  } 
	  C[i][j]=0.0;
	}
      }
        
      d1 = get_dtime();    
      /* 掛け算の計算 */
      for(i = 0; i < N; i++) {
	for(j = 0; j < N; j++) {
	  for(k = 0; k < N; k++) {
            C[i][j] += A[i][k] * B[k][j];
	  }
	}
      }
      
      d2 = get_dtime();
      printf("time= %f[秒]\n", d2-d1);
      
      for(i = 0, sum = 0.0; i < N; i++){
	for(j = 0; j < N; j++){
	  sum += C[i][j];
	}
      }
      
      printf("sum = %f\n", sum);
      
      count++;
  }

  return 0;
}