Misleading Quantity units with pi

[GlaserN]

Is your feature request related to a problem? Please describe.
Inputing a number in radian values needs the unit specifier "Hz"
But inputing a unit in Hz values needs the unit specifier "Hz 2pi"
This is rather counter intuitive and should be changed.

However if you currently use the unit Hz 2pi the input value will be multiplied by 2pi converting from Hz to rad. But it would be more intuitive the other way around to insert a value in Hz with the unit Hz and then transform this value to a radian value, if necessary, e.g. creating the Hamiltonian.

Describe the solution you'd like
Do not transform input value of quantity if 2pi is in the quantity name.
Objects which need a value in radians (e.g. creation of the hamiltonian) should be able to request a value that is in radians and includes a scaling factor dependend on the given unit

Describe alternatives you've considered
Transform an initalized Hz unit to a Hz 2Pi while changing the unit specifier, as well as the value.

Additional context

[GlaserN]

An additional problem with the current implementation is that a modification by get_value and set_value is not straightvorward:

v = Qty(3, unit="Hz 2pi")
v.set_value(v.get_value())

leads to an out of bounds error

[shaimach]

Maybe "Hz" and "rad/s" ? Cumbersome, but clear.

…

On Thu, 28 Jan 2021, 18:37 Niklas Glaser, ***@***.***> wrote: An additional problem with the current implementation is that a modification by get_value and set_value is not straightvorward: v = Qty(3, unit="Hz 2pi") v.set_value(v.get_value()) leads to an out of bounds error — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#26 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAH3Q4K3KXUJQ7IDCDFJLY3S4GHD3ANCNFSM4WXLG4QQ> .

[GlaserN]

The main point is what should be the unit that invokes the following transformation:

c3/c3/c3objs.py

Lines 74 to 79 in ef95330

	if "pi" in unit:
	pref = np.pi
	if "2pi" in unit:
	pref = 2 * np.pi
	else:
	pref = 1.0