It's not undefined. You cannot take the exponential of anything with dimensions. That also applied to logs and trigonometric functions. Ergo, angles must be unitless.
alsimoneau
joined 2 years ago
You disagree that a ratio is unitless? What's the cos of a unit?
No one stops you from putting radians and steradians in your units. But it's unitless by definition.
Proven*
Samples sizes are always small, confounding variables poorly controlled and control groups often contaminated.
Long term effect are also poorly studied.
Except it's not a unit, it's a unitless ratio. You'd have one for every number of dimension. The mol is arguably the extra one.
What prompted the question though?
You're conflating UI and definitions.
Angular velocity can be given in rad/s. No one will bat an eye if you do that. It's even recommended. But it's not a unit in the same sense than the other ones.