template<typename Rep, typename Ratio>
printf_dur( std::chrono::duration< Rep, Ratio > dur )
{
printf( "%lld ticks of %lld/%lld == %.3fs",
(long long int) dur.count(),
(long long int) Ratio::num,
(long long int) Ratio::den,
( (Ratio::num == 1LL)
? (float) dur.count() / (float) Ratio::den
: (float) dur.count() * (float) Ratio::num
)
);
}