http://en.wikipedia.org/wiki/Cycle_per_second

Nonetheless, the change is not without its critics, who argue that the hertz should be redefined as simply a renaming of the cycle per second it displaced, rather than as the reciprocal second[citation needed]. Since SI has adopted the radian as its preferred but dimensionless unit of angle, but left its explicit writing discretionary in unit combinations, the radian per second has perhaps a better claim than the cycle per second to being equivalent to the reciprocal second. But the hertz is overwhelmingly (some would say exclusively) used in the sense of cycle per second, and certainly never used in the sense of radian per second.

以前也有吵過。就像 fourier transform，有的書寫 f*t，有的書寫 omega*t。