//! Convert a utc time to local time
 static time_type utc_to_local(const time_type& t)
 {
   date_type time_t_start_day(1970,1,1);
   time_type time_t_start_time(time_t_start_day,time_duration_type(0,0,0));
   if (t < time_t_start_time) {
     boost::throw_exception(std::out_of_range("Cannot convert dates prior to Jan 1, 1970"));
     BOOST_DATE_TIME_UNREACHABLE_EXPRESSION(return time_t_start_time); // should never reach
   }
 //! Convert a utc time to local time
 static time_type utc_to_local(const time_type& t)
 {
   date_type time_t_start_day(1970,1,1);
   time_type time_t_start_time(time_t_start_day,time_duration_type(0,0,0));
   if (t < time_t_start_time) {
     throw std::out_of_range("Cannot convert dates prior to Jan 1, 1970");
   }
   date_duration_type dd = t.date() - time_t_start_day;
   time_duration_type td = t.time_of_day();
   std::time_t t2 = dd.days()*86400 + td.hours()*3600 + td.minutes()*60 + td.seconds();
   std::tm tms, *tms_ptr;
   tms_ptr = c_time::localtime(&t2, &tms);
   //tms_ptr = std::localtime(&t2);
   date_type d(static_cast<unsigned short>(tms_ptr->tm_year + 1900),
               static_cast<unsigned short>(tms_ptr->tm_mon + 1),
               static_cast<unsigned short>(tms_ptr->tm_mday));
   time_duration_type td2(tms_ptr->tm_hour,
                          tms_ptr->tm_min,
                          tms_ptr->tm_sec,
                          t.time_of_day().fractional_seconds());
   
   return time_type(d,td2);
 }