You signed in with another tab or window. Reload to refresh your session.You signed out in another tab or window. Reload to refresh your session.You switched accounts on another tab or window. Reload to refresh your session.Dismiss alert
{{ message }}
Repository navigation
RPM bug fix created a issue when rescaling hertz #174
changed the title [-]RPM bug fix created a issue when rescaling to a unit based on hertz[/-][+]RPM bug fix created a issue when rescaling hertz[/+]on Feb 26, 2020
This seems to have occurred because of the more complex modeling of rpm that includes pi (notice that it's saying that 60 rpm = 2pi Hertz). I'm not sure the best way to account for this without simplifying the definition of revolution again or writing special case logic somehow.
I think it might help if you could explain the cases that rpm being defined in terms of revolution instead of just 1/min was important. The commit that made that change didn't have tests or anything and the Issue that inspired it didn't have a lot of discussion, IIRC.
The value that rpm was changed to in 393d37e of 2pi / 60 is the value you would expect when asking for the angular velocity of something completing 1 RPM. Specifically, the value of 2pi / 60 radians per second.
The key distinction is that revolutions per minute do not have a unit associated with them, but angular velocity does explicitly include radians.
Activity
[-]RPM bug fix created a issue when rescaling to a unit based on hertz[/-][+]RPM bug fix created a issue when rescaling hertz[/+]apdavison commentedon Feb 27, 2020
hi, do you have any suggestions on how this should be fixed? What is the relationship between a cycle and a revolution?
benhamill commentedon Feb 27, 2020
According to https://www.convertunits.com/from/hertz/to/RPM, 1 hertz = 60 RPM.
This seems to have occurred because of the more complex modeling of rpm that includes pi (notice that it's saying that 60 rpm = 2pi Hertz). I'm not sure the best way to account for this without simplifying the definition of
revolutionagain or writing special case logic somehow.benhamill commentedon Feb 27, 2020
I think it might help if you could explain the cases that
rpmbeing defined in terms ofrevolutioninstead of just1/minwas important. The commit that made that change didn't have tests or anything and the Issue that inspired it didn't have a lot of discussion, IIRC.carl-youngblood commentedon Feb 27, 2020
If I'm reading this correctly https://en.wikipedia.org/wiki/Revolutions_per_minute then RPM should be 1/60.
The value that rpm was changed to in 393d37e of 2pi / 60 is the value you would expect when asking for the angular velocity of something completing 1 RPM. Specifically, the value of 2pi / 60 radians per second.
The key distinction is that revolutions per minute do not have a unit associated with them, but angular velocity does explicitly include radians.