I didn't say standards are science.
I said defining units and standardizing them is science.
Two different things.

Either you didn't read what I said, or you didn't understand. In case it's the latter, I apologize for the lack of clarity in my writing.

But in either case, I'm out.

For anyone visiting this thread with the same complaint in the future, I discovered that the units definition of rpm can be overloaded (redefined) to be 0.0167 Hz by entering the following statement at the top of the SMath document:
OR by entering:

The colon operator is required, to force the statement into definition mode. Using equals will simply try to output the value of the rpm units variable.

I believe that the most correct comment to this topic is the one expressed by Martin Kraska at #9. Some problems of defining SM units in respect of frequency and angular speed are obvious. I therefore believe that the user must take charge of this situation and act accordingly separating the two situations well: if it is frequency it is appropriate to keep the Hz proposed unit if it is an angular speed for example expressed in RPM, you can act manually on the unit of measurement proposed in output (Hz) and modify it in rad / s.
I don't think the solution proposed here by Nalorin to redefine units in that way (which can be functional to automate some calculations) is correct as it leads to confuse the two physical quantities: frequency and angular speed.
sergio

Doctoring °C and rpm is like scratching left hear/right hand.
Bad luck, you can't doctor Reynolds from units input.
That one had shut down for ever the ad noseum Mathcad units.
My Elephant dances of joy ... Jean using Smath.
My Elephant drop river of cries ... Jean using Smath units.

Mathcad is also defining 1 rpm = 2*pi/60s.
If someone want to calculate it as frequency (1/s), then they can do it.
That frequency calculation shall not be wrong.
Claiming smath has a bug is wrong. There is nothing to be fixed.
I have provided printed standards. All known respectable CAS software takes rpm as 0.1047s^-. Debating over this is pointless.
SMath don't have a bug on rpm unit definition.

https://support.ptc.com/help/mathcad/r7.0/en/index.html#page/PTC_Mathcad_Help/frequency_and_angular_velocity_units.html