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by aaaaaaaaaaab 1360 days ago
>Huge selling point for turns, IMHO.

Ok, then let’s measure angles in quarter-turns! Then the equation becomes even nicer:

i^x = cos(x) + isin(x)

Beautiful! :-0

Except not. Because you’re obscuring the connection of sin/cos with their hyperbolic counterparts. I.e. this is no longer true:

sinh(x) = -isin(ix)

cosh(x) = cos(ix)

Also, this new convention obscures the connection with the exponential map of Lie groups.

I.e. the exponential map of the complex unit circle as a Lie group is:

e^ix = cos(x) + isin(x)

Similarly, the exponential map of the unit hyperbola of the split-complex plane is:

e^jx = cosh(x) + jsinh(x)

Similarly, for the group of unit quaternions:

e^q = cos(|q|) + sin(|q|)(q/|q|)

These are deep connections, which would be obscured by using anything other than radians.

1 comments

> Because you’re obscuring the connection of sin/cos with their hyperbolic counterparts.

Only because we forgot the name change: these are supposed to to be nsin and ncos.

Remember also that people use sin and cos with 360-degree degrees just fine; and don't worry about wrecking the connection to the hyperbolic counterparts --- and without changing the names, either.