1  typedef _Complex double ar[];
       2  int f(ar *a, unsigned int n)
       3  {
       4    unsigned int i;
       5    for(i = 0; i< n; i++)
       6      {
       7        (*a)[i*4] = __real__ (*a)[(i+1)*4] + __real__ (*a)[i*4];
       8      }
       9  }