text: /*
   * 3.61
   *
   * $ gcc -O2 -S ex3-61.c # 这样就不会使循环的值溢出到存储器了
   */
  
  /* Compute i,k of variable matrix product */
  int var_prod_ele(int n, int A[n][n], int B[n][n], int i, int k) {
      int j;
      int result = 0;
  
      void *Arow = (void *) &A[i][0];
      void *Bcol = (void *) &B[0][k];
  
      int N = 4 * n;
      for (j = 0; j < N; j += 4)
          result += *(int *) (Arow + j) * *(int *) (Bcol + N);
  
      return result;
  }
  