Arduino PID Library

Hi br3ttb,
Nice work out there. Library is awesome.I am still studying, not implemented yet. But I like to ask you something. There is a function that is:

void SetSampleTime(int NewSampleTime)
{
if (NewSampleTime > 0)
{
//convert the time-based tunings to reflect this change
taur *= ((double)NewSampleTime)/((double) tSample);
accError *= ((double) tSample)/((double)NewSampleTime);
taud *= ((double)NewSampleTime)/((double) tSample);
tSample = (unsigned long)NewSampleTime;
}
}

I am confused about this line: taud *= ((double)NewSampleTime)/((double) tSample);
Shouldn't it be: taud /= ((double)NewSampleTime)/((double) tSample);
or taud *= ((double)) tSample/((double) NewSampleTime);

I mean: taud=TauD/tSampleInSec , right?